Add OnDemandShardState to report additional Shard state
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / test / java / org / opendaylight / controller / cluster / datastore / ShardTest.java
index e3b82df1743e75c433cec193d54a2cbfbd696319..45cfd29d255af37b91df19553261570079c65081 100644 (file)
@@ -1,18 +1,29 @@
+/*
+ * Copyright (c) 2014, 2015 Cisco Systems, Inc. and others.  All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
 package org.opendaylight.controller.cluster.datastore;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Mockito.doReturn;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.mock;
 import static org.opendaylight.controller.cluster.datastore.DataStoreVersions.CURRENT_VERSION;
+
 import akka.actor.ActorRef;
 import akka.actor.ActorSelection;
-import akka.actor.PoisonPill;
 import akka.actor.Props;
+import akka.actor.Status.Failure;
 import akka.dispatch.Dispatchers;
 import akka.dispatch.OnComplete;
 import akka.japi.Creator;
@@ -20,20 +31,15 @@ import akka.pattern.Patterns;
 import akka.persistence.SaveSnapshotSuccess;
 import akka.testkit.TestActorRef;
 import akka.util.Timeout;
-import com.google.common.base.Function;
-import com.google.common.base.Optional;
-import com.google.common.util.concurrent.Futures;
-import com.google.common.util.concurrent.ListenableFuture;
-import com.google.common.util.concurrent.MoreExecutors;
+import com.google.common.base.Stopwatch;
+import com.google.common.base.Throwables;
 import com.google.common.util.concurrent.Uninterruptibles;
 import java.io.IOException;
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
@@ -41,7 +47,12 @@ import org.junit.Test;
 import org.mockito.InOrder;
 import org.opendaylight.controller.cluster.DataPersistenceProvider;
 import org.opendaylight.controller.cluster.DelegatingPersistentDataProvider;
+import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
+import org.opendaylight.controller.cluster.access.concepts.MemberName;
+import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
+import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
+import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
 import org.opendaylight.controller.cluster.datastore.messages.AbortTransactionReply;
 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
@@ -51,93 +62,101 @@ import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransacti
 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
 import org.opendaylight.controller.cluster.datastore.messages.CommitTransactionReply;
 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
-import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
+import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
 import org.opendaylight.controller.cluster.datastore.messages.ReadData;
 import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
+import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListener;
 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListenerReply;
+import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
+import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListenerReply;
+import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
-import org.opendaylight.controller.cluster.datastore.modification.DeleteModification;
 import org.opendaylight.controller.cluster.datastore.modification.MergeModification;
-import org.opendaylight.controller.cluster.datastore.modification.Modification;
-import org.opendaylight.controller.cluster.datastore.modification.ModificationPayload;
-import org.opendaylight.controller.cluster.datastore.modification.MutableCompositeModification;
 import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
-import org.opendaylight.controller.cluster.datastore.utils.MessageCollectorActor;
+import org.opendaylight.controller.cluster.datastore.persisted.MetadataShardDataTreeSnapshot;
+import org.opendaylight.controller.cluster.datastore.persisted.ShardSnapshotState;
 import org.opendaylight.controller.cluster.datastore.utils.MockDataChangeListener;
-import org.opendaylight.controller.cluster.datastore.utils.SerializationUtils;
+import org.opendaylight.controller.cluster.datastore.utils.MockDataTreeChangeListener;
 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListenerReply;
 import org.opendaylight.controller.cluster.raft.RaftActorContext;
 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
-import org.opendaylight.controller.cluster.raft.ReplicatedLogImplEntry;
-import org.opendaylight.controller.cluster.raft.Snapshot;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplyJournalEntries;
 import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
-import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
 import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout;
 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
+import org.opendaylight.controller.cluster.raft.base.messages.TimeoutNow;
 import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
 import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
+import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
+import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
+import org.opendaylight.controller.cluster.raft.messages.RequestVote;
+import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
+import org.opendaylight.controller.cluster.raft.persisted.ApplyJournalEntries;
+import org.opendaylight.controller.cluster.raft.persisted.SimpleReplicatedLogEntry;
+import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
+import org.opendaylight.controller.cluster.raft.policy.DisableElectionsRaftPolicy;
+import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
 import org.opendaylight.controller.cluster.raft.utils.InMemoryJournal;
-import org.opendaylight.controller.cluster.raft.utils.InMemorySnapshotStore;
+import org.opendaylight.controller.cluster.raft.utils.MessageCollectorActor;
 import org.opendaylight.controller.md.cluster.datastore.model.SchemaContextHelper;
 import org.opendaylight.controller.md.cluster.datastore.model.TestModel;
 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataBroker;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
-import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStore;
-import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStoreFactory;
-import org.opendaylight.controller.protobuff.messages.cohort3pc.ThreePhaseCommitCohortMessages;
-import org.opendaylight.controller.protobuff.messages.transaction.ShardTransactionMessages.CreateTransactionReply;
-import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
-import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
-import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
 import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
-import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
-import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
+import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.TipProducingDataTree;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
-import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+import org.opendaylight.yangtools.yang.data.impl.schema.builder.impl.ImmutableContainerNodeBuilder;
+import org.opendaylight.yangtools.yang.data.impl.schema.tree.InMemoryDataTreeFactory;
 import scala.concurrent.Await;
 import scala.concurrent.Future;
 import scala.concurrent.duration.FiniteDuration;
 
 public class ShardTest extends AbstractShardTest {
+    private static final String DUMMY_DATA = "Dummy data as snapshot sequence number is set to 0 in "
+            + "InMemorySnapshotStore and journal recovery seq number will start from 1";
 
     @Test
     public void testRegisterChangeListener() throws Exception {
-        new ShardTestKit(getSystem()) {{
-            TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps(),  "testRegisterChangeListener");
-
-            waitUntilLeader(shard);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testRegisterChangeListener");
 
-            shard.tell(new UpdateSchemaContext(SchemaContextHelper.full()), ActorRef.noSender());
+                waitUntilLeader(shard);
 
-            MockDataChangeListener listener = new MockDataChangeListener(1);
-            ActorRef dclActor = getSystem().actorOf(DataChangeListener.props(listener),
-                    "testRegisterChangeListener-DataChangeListener");
+                shard.tell(new UpdateSchemaContext(SchemaContextHelper.full()), ActorRef.noSender());
 
-            shard.tell(new RegisterChangeListener(TestModel.TEST_PATH,
-                    dclActor, AsyncDataBroker.DataChangeScope.BASE), getRef());
+                final MockDataChangeListener listener = new MockDataChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataChangeListener.props(listener,
+                        TestModel.TEST_PATH), "testRegisterChangeListener-DataChangeListener");
 
-            RegisterChangeListenerReply reply = expectMsgClass(duration("3 seconds"),
-                    RegisterChangeListenerReply.class);
-            String replyPath = reply.getListenerRegistrationPath().toString();
-            assertTrue("Incorrect reply path: " + replyPath, replyPath.matches(
-                    "akka:\\/\\/test\\/user\\/testRegisterChangeListener\\/\\$.*"));
+                shard.tell(new RegisterChangeListener(TestModel.TEST_PATH, dclActor,
+                        AsyncDataBroker.DataChangeScope.BASE, true), getRef());
 
-            YangInstanceIdentifier path = TestModel.TEST_PATH;
-            writeToStore(shard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+                final RegisterChangeListenerReply reply = expectMsgClass(duration("3 seconds"),
+                        RegisterChangeListenerReply.class);
+                final String replyPath = reply.getListenerRegistrationPath().toString();
+                assertTrue("Incorrect reply path: " + replyPath,
+                        replyPath.matches("akka:\\/\\/test\\/user\\/testRegisterChangeListener\\/\\$.*"));
 
-            listener.waitForChangeEvents(path);
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                writeToStore(shard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
 
-            dclActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                listener.waitForChangeEvents(path);
+            }
+        };
     }
 
     @SuppressWarnings("serial")
@@ -146,1261 +165,1726 @@ public class ShardTest extends AbstractShardTest {
         // This test tests the timing window in which a change listener is registered before the
         // shard becomes the leader. We verify that the listener is registered and notified of the
         // existing data when the shard becomes the leader.
-        new ShardTestKit(getSystem()) {{
-            // For this test, we want to send the RegisterChangeListener message after the shard
-            // has recovered from persistence and before it becomes the leader. So we subclass
-            // Shard to override onReceiveCommand and, when the first ElectionTimeout is received,
-            // we know that the shard has been initialized to a follower and has started the
-            // election process. The following 2 CountDownLatches are used to coordinate the
-            // ElectionTimeout with the sending of the RegisterChangeListener message.
-            final CountDownLatch onFirstElectionTimeout = new CountDownLatch(1);
-            final CountDownLatch onChangeListenerRegistered = new CountDownLatch(1);
-            Creator<Shard> creator = new Creator<Shard>() {
-                boolean firstElectionTimeout = true;
-
-                @Override
-                public Shard create() throws Exception {
-                    // Use a non persistent provider because this test actually invokes persist on the journal
-                    // this will cause all other messages to not be queued properly after that.
-                    // The basic issue is that you cannot use TestActorRef with a persistent actor (at least when
-                    // it does do a persist)
-                    return new Shard(shardID, Collections.<String,String>emptyMap(),
-                            dataStoreContextBuilder.persistent(false).build(), SCHEMA_CONTEXT) {
-                        @Override
-                        public void onReceiveCommand(final Object message) throws Exception {
-                            if(message instanceof ElectionTimeout && firstElectionTimeout) {
-                                // Got the first ElectionTimeout. We don't forward it to the
-                                // base Shard yet until we've sent the RegisterChangeListener
-                                // message. So we signal the onFirstElectionTimeout latch to tell
-                                // the main thread to send the RegisterChangeListener message and
-                                // start a thread to wait on the onChangeListenerRegistered latch,
-                                // which the main thread signals after it has sent the message.
-                                // After the onChangeListenerRegistered is triggered, we send the
-                                // original ElectionTimeout message to proceed with the election.
-                                firstElectionTimeout = false;
-                                final ActorRef self = getSelf();
-                                new Thread() {
-                                    @Override
-                                    public void run() {
-                                        Uninterruptibles.awaitUninterruptibly(
-                                                onChangeListenerRegistered, 5, TimeUnit.SECONDS);
-                                        self.tell(message, self);
-                                    }
-                                }.start();
-
-                                onFirstElectionTimeout.countDown();
-                            } else {
-                                super.onReceiveCommand(message);
-                            }
-                        }
-                    };
-                }
-            };
-
-            MockDataChangeListener listener = new MockDataChangeListener(1);
-            ActorRef dclActor = getSystem().actorOf(DataChangeListener.props(listener),
-                    "testRegisterChangeListenerWhenNotLeaderInitially-DataChangeListener");
-
-            TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    Props.create(new DelegatingShardCreator(creator)),
-                    "testRegisterChangeListenerWhenNotLeaderInitially");
-
-            // Write initial data into the in-memory store.
-            YangInstanceIdentifier path = TestModel.TEST_PATH;
-            writeToStore(shard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
-
-            // Wait until the shard receives the first ElectionTimeout message.
-            assertEquals("Got first ElectionTimeout", true,
-                    onFirstElectionTimeout.await(5, TimeUnit.SECONDS));
+        // For this test, we want to send the RegisterChangeListener message after the shard
+        // has recovered from persistence and before it becomes the leader. So we subclass
+        // Shard to override onReceiveCommand and, when the first ElectionTimeout is received,
+        // we know that the shard has been initialized to a follower and has started the
+        // election process. The following 2 CountDownLatches are used to coordinate the
+        // ElectionTimeout with the sending of the RegisterChangeListener message.
+        final CountDownLatch onFirstElectionTimeout = new CountDownLatch(1);
+        final CountDownLatch onChangeListenerRegistered = new CountDownLatch(1);
+        final Creator<Shard> creator = new Creator<Shard>() {
+            boolean firstElectionTimeout = true;
 
-            // Now send the RegisterChangeListener and wait for the reply.
-            shard.tell(new RegisterChangeListener(path, dclActor,
-                    AsyncDataBroker.DataChangeScope.SUBTREE), getRef());
-
-            RegisterChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
-                    RegisterChangeListenerReply.class);
-            assertNotNull("getListenerRegistrationPath", reply.getListenerRegistrationPath());
+            @Override
+            public Shard create() throws Exception {
+                // Use a non persistent provider because this test actually invokes persist on the journal
+                // this will cause all other messages to not be queued properly after that.
+                // The basic issue is that you cannot use TestActorRef with a persistent actor (at least when
+                // it does do a persist)
+                return new Shard(newShardBuilder()) {
+                    @Override
+                    public void handleCommand(final Object message) {
+                        if (message instanceof ElectionTimeout && firstElectionTimeout) {
+                            // Got the first ElectionTimeout. We don't forward it to the
+                            // base Shard yet until we've sent the RegisterChangeListener
+                            // message. So we signal the onFirstElectionTimeout latch to tell
+                            // the main thread to send the RegisterChangeListener message and
+                            // start a thread to wait on the onChangeListenerRegistered latch,
+                            // which the main thread signals after it has sent the message.
+                            // After the onChangeListenerRegistered is triggered, we send the
+                            // original ElectionTimeout message to proceed with the election.
+                            firstElectionTimeout = false;
+                            final ActorRef self = getSelf();
+                            new Thread() {
+                                @Override
+                                public void run() {
+                                    Uninterruptibles.awaitUninterruptibly(
+                                            onChangeListenerRegistered, 5, TimeUnit.SECONDS);
+                                    self.tell(message, self);
+                                }
+                            }.start();
+
+                            onFirstElectionTimeout.countDown();
+                        } else {
+                            super.handleCommand(message);
+                        }
+                    }
+                };
+            }
+        };
 
-            // Sanity check - verify the shard is not the leader yet.
-            shard.tell(new FindLeader(), getRef());
-            FindLeaderReply findLeadeReply =
-                    expectMsgClass(duration("5 seconds"), FindLeaderReply.class);
-            assertNull("Expected the shard not to be the leader", findLeadeReply.getLeaderActor());
+        setupInMemorySnapshotStore();
 
-            // Signal the onChangeListenerRegistered latch to tell the thread above to proceed
-            // with the election process.
-            onChangeListenerRegistered.countDown();
+        final YangInstanceIdentifier path = TestModel.TEST_PATH;
+        final MockDataChangeListener listener = new MockDataChangeListener(1);
+        final ActorRef dclActor = actorFactory.createActor(DataChangeListener.props(listener, path),
+                "testRegisterChangeListenerWhenNotLeaderInitially-DataChangeListener");
 
-            // Wait for the shard to become the leader and notify our listener with the existing
-            // data in the store.
-            listener.waitForChangeEvents(path);
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                Props.create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()),
+                "testRegisterChangeListenerWhenNotLeaderInitially");
 
-            dclActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+        new ShardTestKit(getSystem()) {
+            {
+                // Wait until the shard receives the first ElectionTimeout
+                // message.
+                assertEquals("Got first ElectionTimeout", true, onFirstElectionTimeout.await(5, TimeUnit.SECONDS));
+
+                // Now send the RegisterChangeListener and wait for the reply.
+                shard.tell(new RegisterChangeListener(path, dclActor, AsyncDataBroker.DataChangeScope.SUBTREE, false),
+                        getRef());
+
+                final RegisterChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterChangeListenerReply.class);
+                assertNotNull("getListenerRegistrationPath", reply.getListenerRegistrationPath());
+
+                // Sanity check - verify the shard is not the leader yet.
+                shard.tell(FindLeader.INSTANCE, getRef());
+                final FindLeaderReply findLeadeReply = expectMsgClass(duration("5 seconds"), FindLeaderReply.class);
+                assertFalse("Expected the shard not to be the leader", findLeadeReply.getLeaderActor().isPresent());
+
+                // Signal the onChangeListenerRegistered latch to tell the
+                // thread above to proceed
+                // with the election process.
+                onChangeListenerRegistered.countDown();
+
+                // Wait for the shard to become the leader and notify our
+                // listener with the existing
+                // data in the store.
+                listener.waitForChangeEvents(path);
+            }
+        };
     }
 
     @Test
-    public void testCreateTransaction(){
-        new ShardTestKit(getSystem()) {{
-            ActorRef shard = getSystem().actorOf(newShardProps(), "testCreateTransaction");
-
-            waitUntilLeader(shard);
-
-            shard.tell(new UpdateSchemaContext(TestModel.createTestContext()), getRef());
-
-            shard.tell(new CreateTransaction("txn-1",
-                    TransactionProxy.TransactionType.READ_ONLY.ordinal() ).toSerializable(), getRef());
-
-            CreateTransactionReply reply = expectMsgClass(duration("3 seconds"),
-                    CreateTransactionReply.class);
-
-            String path = reply.getTransactionActorPath().toString();
-            assertTrue("Unexpected transaction path " + path,
-                    path.contains("akka://test/user/testCreateTransaction/shard-txn-1"));
+    public void testRegisterDataTreeChangeListener() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testRegisterDataTreeChangeListener");
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                waitUntilLeader(shard);
 
-    @Test
-    public void testCreateTransactionOnChain(){
-        new ShardTestKit(getSystem()) {{
-            final ActorRef shard = getSystem().actorOf(newShardProps(), "testCreateTransactionOnChain");
+                shard.tell(new UpdateSchemaContext(SchemaContextHelper.full()), ActorRef.noSender());
 
-            waitUntilLeader(shard);
+                final MockDataTreeChangeListener listener = new MockDataTreeChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataTreeChangeListenerActor.props(listener,
+                        TestModel.TEST_PATH), "testRegisterDataTreeChangeListener-DataTreeChangeListener");
 
-            shard.tell(new CreateTransaction("txn-1",
-                    TransactionProxy.TransactionType.READ_ONLY.ordinal() , "foobar").toSerializable(),
-                    getRef());
+                shard.tell(new RegisterDataTreeChangeListener(TestModel.TEST_PATH, dclActor, false), getRef());
 
-            CreateTransactionReply reply = expectMsgClass(duration("3 seconds"),
-                    CreateTransactionReply.class);
+                final RegisterDataTreeChangeListenerReply reply = expectMsgClass(duration("3 seconds"),
+                        RegisterDataTreeChangeListenerReply.class);
+                final String replyPath = reply.getListenerRegistrationPath().toString();
+                assertTrue("Incorrect reply path: " + replyPath,
+                        replyPath.matches("akka:\\/\\/test\\/user\\/testRegisterDataTreeChangeListener\\/\\$.*"));
 
-            String path = reply.getTransactionActorPath().toString();
-            assertTrue("Unexpected transaction path " + path,
-                    path.contains("akka://test/user/testCreateTransactionOnChain/shard-txn-1"));
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                writeToStore(shard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                listener.waitForChangeEvents();
+            }
+        };
     }
 
     @SuppressWarnings("serial")
     @Test
-    public void testPeerAddressResolved() throws Exception {
-        new ShardTestKit(getSystem()) {{
-            final CountDownLatch recoveryComplete = new CountDownLatch(1);
-            class TestShard extends Shard {
-                TestShard() {
-                    super(shardID, Collections.<String, String>singletonMap(shardID.toString(), null),
-                            newDatastoreContext(), SCHEMA_CONTEXT);
-                }
-
-                Map<String, String> getPeerAddresses() {
-                    return getRaftActorContext().getPeerAddresses();
-                }
+    public void testDataTreeChangeListenerNotifiedWhenNotTheLeaderOnRegistration() throws Exception {
+        final CountDownLatch onFirstElectionTimeout = new CountDownLatch(1);
+        final CountDownLatch onChangeListenerRegistered = new CountDownLatch(1);
+        final Creator<Shard> creator = new Creator<Shard>() {
+            boolean firstElectionTimeout = true;
 
-                @Override
-                protected void onRecoveryComplete() {
-                    try {
-                        super.onRecoveryComplete();
-                    } finally {
-                        recoveryComplete.countDown();
+            @Override
+            public Shard create() throws Exception {
+                return new Shard(newShardBuilder()) {
+                    @Override
+                    public void handleCommand(final Object message) {
+                        if (message instanceof ElectionTimeout && firstElectionTimeout) {
+                            firstElectionTimeout = false;
+                            final ActorRef self = getSelf();
+                            new Thread() {
+                                @Override
+                                public void run() {
+                                    Uninterruptibles.awaitUninterruptibly(
+                                            onChangeListenerRegistered, 5, TimeUnit.SECONDS);
+                                    self.tell(message, self);
+                                }
+                            }.start();
+
+                            onFirstElectionTimeout.countDown();
+                        } else {
+                            super.handleCommand(message);
+                        }
                     }
-                }
+                };
             }
+        };
 
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    Props.create(new DelegatingShardCreator(new Creator<Shard>() {
-                        @Override
-                        public TestShard create() throws Exception {
-                            return new TestShard();
-                        }
-                    })), "testPeerAddressResolved");
+        setupInMemorySnapshotStore();
 
-            //waitUntilLeader(shard);
-            assertEquals("Recovery complete", true,
-                    Uninterruptibles.awaitUninterruptibly(recoveryComplete, 5, TimeUnit.SECONDS));
+        final YangInstanceIdentifier path = TestModel.TEST_PATH;
+        final MockDataTreeChangeListener listener = new MockDataTreeChangeListener(1);
+        final ActorRef dclActor = actorFactory.createActor(DataTreeChangeListenerActor.props(listener, path),
+                "testDataTreeChangeListenerNotifiedWhenNotTheLeaderOnRegistration-DataChangeListener");
 
-            String address = "akka://foobar";
-            shard.underlyingActor().onReceiveCommand(new PeerAddressResolved(shardID.toString(), address));
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                Props.create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()),
+                "testDataTreeChangeListenerNotifiedWhenNotTheLeaderOnRegistration");
 
-            assertEquals("getPeerAddresses", address,
-                    ((TestShard)shard.underlyingActor()).getPeerAddresses().get(shardID.toString()));
+        new ShardTestKit(getSystem()) {
+            {
+                assertEquals("Got first ElectionTimeout", true, onFirstElectionTimeout.await(5, TimeUnit.SECONDS));
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                shard.tell(new RegisterDataTreeChangeListener(path, dclActor, false), getRef());
+                final RegisterDataTreeChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterDataTreeChangeListenerReply.class);
+                assertNotNull("getListenerRegistratioznPath", reply.getListenerRegistrationPath());
 
-    @Test
-    public void testApplySnapshot() throws Exception {
-        TestActorRef<Shard> shard = TestActorRef.create(getSystem(), newShardProps(),
-                "testApplySnapshot");
+                shard.tell(FindLeader.INSTANCE, getRef());
+                final FindLeaderReply findLeadeReply = expectMsgClass(duration("5 seconds"), FindLeaderReply.class);
+                assertFalse("Expected the shard not to be the leader", findLeadeReply.getLeaderActor().isPresent());
 
-        InMemoryDOMDataStore store = new InMemoryDOMDataStore("OPER", MoreExecutors.sameThreadExecutor());
-        store.onGlobalContextUpdated(SCHEMA_CONTEXT);
+                onChangeListenerRegistered.countDown();
 
-        writeToStore(store, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+                // TODO: investigate why we do not receive data chage events
+                listener.waitForChangeEvents();
+            }
+        };
+    }
 
-        YangInstanceIdentifier root = YangInstanceIdentifier.builder().build();
-        NormalizedNode<?,?> expected = readStore(store, root);
+    @Test
+    public void testCreateTransaction() {
+        new ShardTestKit(getSystem()) {
+            {
+                final ActorRef shard = actorFactory.createActor(newShardProps(), "testCreateTransaction");
 
-        ApplySnapshot applySnapshot = new ApplySnapshot(Snapshot.create(
-                SerializationUtils.serializeNormalizedNode(expected),
-                Collections.<ReplicatedLogEntry>emptyList(), 1, 2, 3, 4));
+                waitUntilLeader(shard);
 
-        shard.underlyingActor().onReceiveCommand(applySnapshot);
+                shard.tell(new UpdateSchemaContext(TestModel.createTestContext()), getRef());
 
-        NormalizedNode<?,?> actual = readStore(shard, root);
+                shard.tell(new CreateTransaction(nextTransactionId(), TransactionType.READ_ONLY.ordinal(),
+                        DataStoreVersions.CURRENT_VERSION).toSerializable(), getRef());
 
-        assertEquals("Root node", expected, actual);
+                final CreateTransactionReply reply = expectMsgClass(duration("3 seconds"),
+                        CreateTransactionReply.class);
 
-        shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                final String path = reply.getTransactionPath().toString();
+                assertTrue("Unexpected transaction path " + path, path
+                        .startsWith("akka://test/user/testCreateTransaction/shard-member-1:ShardTransactionTest@0:"));
+            }
+        };
     }
 
     @Test
-    public void testApplyState() throws Exception {
-
-        TestActorRef<Shard> shard = TestActorRef.create(getSystem(), newShardProps(), "testApplyState");
-
-        NormalizedNode<?, ?> node = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+    public void testCreateTransactionOnChain() {
+        new ShardTestKit(getSystem()) {
+            {
+                final ActorRef shard = actorFactory.createActor(newShardProps(), "testCreateTransactionOnChain");
 
-        ApplyState applyState = new ApplyState(null, "test", new ReplicatedLogImplEntry(1, 2,
-                newModificationPayload(new WriteModification(TestModel.TEST_PATH, node))));
+                waitUntilLeader(shard);
 
-        shard.underlyingActor().onReceiveCommand(applyState);
+                shard.tell(new CreateTransaction(nextTransactionId(), TransactionType.READ_ONLY.ordinal(),
+                        DataStoreVersions.CURRENT_VERSION).toSerializable(), getRef());
 
-        NormalizedNode<?,?> actual = readStore(shard, TestModel.TEST_PATH);
-        assertEquals("Applied state", node, actual);
+                final CreateTransactionReply reply = expectMsgClass(duration("3 seconds"),
+                        CreateTransactionReply.class);
 
-        shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                final String path = reply.getTransactionPath().toString();
+                assertTrue("Unexpected transaction path " + path, path.startsWith(
+                        "akka://test/user/testCreateTransactionOnChain/shard-member-1:ShardTransactionTest@0:"));
+            }
+        };
     }
 
     @Test
-    public void testRecovery() throws Exception {
-
-        // Set up the InMemorySnapshotStore.
+    public void testPeerAddressResolved() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final ShardIdentifier peerID = ShardIdentifier.create("inventory", MemberName.forName("member-2"),
+                        "config");
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(newShardBuilder()
+                        .peerAddresses(Collections.<String, String>singletonMap(peerID.toString(), null))
+                        .props().withDispatcher(Dispatchers.DefaultDispatcherId()), "testPeerAddressResolved");
+
+                final String address = "akka://foobar";
+                shard.tell(new PeerAddressResolved(peerID.toString(), address), ActorRef.noSender());
+
+                shard.tell(GetOnDemandRaftState.INSTANCE, getRef());
+                final OnDemandRaftState state = expectMsgClass(OnDemandRaftState.class);
+                assertEquals("getPeerAddress", address, state.getPeerAddresses().get(peerID.toString()));
+            }
+        };
+    }
 
-        InMemoryDOMDataStore testStore = InMemoryDOMDataStoreFactory.create("Test", null, null);
-        testStore.onGlobalContextUpdated(SCHEMA_CONTEXT);
+    @Test
+    public void testApplySnapshot() throws Exception {
 
-        writeToStore(testStore, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(newShardProps()
+                .withDispatcher(Dispatchers.DefaultDispatcherId()), "testApplySnapshot");
 
-        NormalizedNode<?, ?> root = readStore(testStore, YangInstanceIdentifier.builder().build());
+        ShardTestKit.waitUntilLeader(shard);
 
-        InMemorySnapshotStore.addSnapshot(shardID.toString(), Snapshot.create(
-                SerializationUtils.serializeNormalizedNode(root),
-                Collections.<ReplicatedLogEntry>emptyList(), 0, 1, -1, -1));
+        final DataTree store = InMemoryDataTreeFactory.getInstance().create(TreeType.OPERATIONAL);
+        store.setSchemaContext(SCHEMA_CONTEXT);
 
-        // Set up the InMemoryJournal.
+        final ContainerNode container = ImmutableContainerNodeBuilder.create().withNodeIdentifier(
+                new YangInstanceIdentifier.NodeIdentifier(TestModel.TEST_QNAME))
+                    .withChild(ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).addChild(
+                        ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1)).build()).build();
 
-        InMemoryJournal.addEntry(shardID.toString(), 0, new ReplicatedLogImplEntry(0, 1, newModificationPayload(
-                  new WriteModification(TestModel.OUTER_LIST_PATH,
-                          ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build()))));
+        writeToStore(store, TestModel.TEST_PATH, container);
 
-        int nListEntries = 16;
-        Set<Integer> listEntryKeys = new HashSet<>();
+        final YangInstanceIdentifier root = YangInstanceIdentifier.EMPTY;
+        final NormalizedNode<?,?> expected = readStore(store, root);
 
-        // Add some ModificationPayload entries
-        for(int i = 1; i <= nListEntries; i++) {
-            listEntryKeys.add(Integer.valueOf(i));
-            YangInstanceIdentifier path = YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
-                    .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, i).build();
-            Modification mod = new MergeModification(path,
-                    ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, i));
-            InMemoryJournal.addEntry(shardID.toString(), i, new ReplicatedLogImplEntry(i, 1,
-                    newModificationPayload(mod)));
-        }
+        final Snapshot snapshot = Snapshot.create(
+                new ShardSnapshotState(new MetadataShardDataTreeSnapshot(expected)),
+                Collections.<ReplicatedLogEntry>emptyList(), 1, 2, 3, 4, -1, null, null);
 
-        InMemoryJournal.addEntry(shardID.toString(), nListEntries + 1,
-                new ApplyJournalEntries(nListEntries));
+        shard.tell(new ApplySnapshot(snapshot), ActorRef.noSender());
 
-        testRecovery(listEntryKeys);
-    }
+        final Stopwatch sw = Stopwatch.createStarted();
+        while (sw.elapsed(TimeUnit.SECONDS) <= 5) {
+            Uninterruptibles.sleepUninterruptibly(75, TimeUnit.MILLISECONDS);
 
-    private ModificationPayload newModificationPayload(final Modification... mods) throws IOException {
-        MutableCompositeModification compMod = new MutableCompositeModification();
-        for(Modification mod: mods) {
-            compMod.addModification(mod);
+            try {
+                assertEquals("Root node", expected, readStore(shard, root));
+                return;
+            } catch (final AssertionError e) {
+                // try again
+            }
         }
 
-        return new ModificationPayload(compMod);
+        fail("Snapshot was not applied");
     }
 
-    @SuppressWarnings({ "unchecked" })
     @Test
-    public void testConcurrentThreePhaseCommits() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testConcurrentThreePhaseCommits");
-
-            waitUntilLeader(shard);
+    public void testApplyState() throws Exception {
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()), "testApplyState");
 
-         // Setup 3 simulated transactions with mock cohorts backed by real cohorts.
+        ShardTestKit.waitUntilLeader(shard);
 
-            InMemoryDOMDataStore dataStore = shard.underlyingActor().getDataStore();
+        final DataTree store = InMemoryDataTreeFactory.getInstance().create(TreeType.OPERATIONAL);
+        store.setSchemaContext(SCHEMA_CONTEXT);
 
-            String transactionID1 = "tx1";
-            MutableCompositeModification modification1 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort1 = setupMockWriteTransaction("cohort1", dataStore,
-                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME), modification1);
+        final DataTreeModification writeMod = store.takeSnapshot().newModification();
+        final ContainerNode node = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+        writeMod.write(TestModel.TEST_PATH, node);
+        writeMod.ready();
 
-            String transactionID2 = "tx2";
-            MutableCompositeModification modification2 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort2 = setupMockWriteTransaction("cohort2", dataStore,
-                    TestModel.OUTER_LIST_PATH,
-                    ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(),
-                    modification2);
+        final TransactionIdentifier tx = nextTransactionId();
+        shard.underlyingActor().applyState(null, null, payloadForModification(store, writeMod, tx));
 
-            String transactionID3 = "tx3";
-            MutableCompositeModification modification3 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort3 = setupMockWriteTransaction("cohort3", dataStore,
-                    YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
-                        .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
-                    ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1),
-                    modification3);
+        final Stopwatch sw = Stopwatch.createStarted();
+        while (sw.elapsed(TimeUnit.SECONDS) <= 5) {
+            Uninterruptibles.sleepUninterruptibly(75, TimeUnit.MILLISECONDS);
 
-            long timeoutSec = 5;
-            final FiniteDuration duration = FiniteDuration.create(timeoutSec, TimeUnit.SECONDS);
-            final Timeout timeout = new Timeout(duration);
+            final NormalizedNode<?,?> actual = readStore(shard, TestModel.TEST_PATH);
+            if (actual != null) {
+                assertEquals("Applied state", node, actual);
+                return;
+            }
+        }
 
-            // Simulate the ForwardedReadyTransaction message for the first Tx that would be sent
-            // by the ShardTransaction.
+        fail("State was not applied");
+    }
 
-            shard.tell(new ForwardedReadyTransaction(transactionID1, CURRENT_VERSION,
-                    cohort1, modification1, true), getRef());
-            ReadyTransactionReply readyReply = ReadyTransactionReply.fromSerializable(
-                    expectMsgClass(duration, ReadyTransactionReply.class));
-            assertEquals("Cohort path", shard.path().toString(), readyReply.getCohortPath());
+    @Test
+    public void testDataTreeCandidateRecovery() throws Exception {
+        // Set up the InMemorySnapshotStore.
+        final DataTree source = setupInMemorySnapshotStore();
 
-            // Send the CanCommitTransaction message for the first Tx.
+        final DataTreeModification writeMod = source.takeSnapshot().newModification();
+        writeMod.write(TestModel.OUTER_LIST_PATH, ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build());
+        writeMod.ready();
+        InMemoryJournal.addEntry(shardID.toString(), 0, DUMMY_DATA);
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+        // Set up the InMemoryJournal.
+        InMemoryJournal.addEntry(shardID.toString(), 1, new SimpleReplicatedLogEntry(0, 1,
+            payloadForModification(source, writeMod, nextTransactionId())));
 
-            // Send the ForwardedReadyTransaction for the next 2 Tx's.
+        final int nListEntries = 16;
+        final Set<Integer> listEntryKeys = new HashSet<>();
 
-            shard.tell(new ForwardedReadyTransaction(transactionID2, CURRENT_VERSION,
-                    cohort2, modification2, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+        // Add some ModificationPayload entries
+        for (int i = 1; i <= nListEntries; i++) {
+            listEntryKeys.add(Integer.valueOf(i));
 
-            shard.tell(new ForwardedReadyTransaction(transactionID3, CURRENT_VERSION,
-                    cohort3, modification3, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+            final YangInstanceIdentifier path = YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                    .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, i).build();
 
-            // Send the CanCommitTransaction message for the next 2 Tx's. These should get queued and
-            // processed after the first Tx completes.
+            final DataTreeModification mod = source.takeSnapshot().newModification();
+            mod.merge(path, ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, i));
+            mod.ready();
 
-            Future<Object> canCommitFuture1 = Patterns.ask(shard,
-                    new CanCommitTransaction(transactionID2).toSerializable(), timeout);
+            InMemoryJournal.addEntry(shardID.toString(), i + 1, new SimpleReplicatedLogEntry(i, 1,
+                payloadForModification(source, mod, nextTransactionId())));
+        }
 
-            Future<Object> canCommitFuture2 = Patterns.ask(shard,
-                    new CanCommitTransaction(transactionID3).toSerializable(), timeout);
+        InMemoryJournal.addEntry(shardID.toString(), nListEntries + 2,
+            new ApplyJournalEntries(nListEntries));
 
-            // Send the CommitTransaction message for the first Tx. After it completes, it should
-            // trigger the 2nd Tx to proceed which should in turn then trigger the 3rd.
+        testRecovery(listEntryKeys);
+    }
 
-            shard.tell(new CommitTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+    @Test
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public void testConcurrentThreePhaseCommits() throws Exception {
+        final AtomicReference<Throwable> caughtEx = new AtomicReference<>();
+        final CountDownLatch commitLatch = new CountDownLatch(2);
 
-            // Wait for the next 2 Tx's to complete.
+        final long timeoutSec = 5;
+        final FiniteDuration duration = FiniteDuration.create(timeoutSec, TimeUnit.SECONDS);
+        final Timeout timeout = new Timeout(duration);
 
-            final AtomicReference<Throwable> caughtEx = new AtomicReference<>();
-            final CountDownLatch commitLatch = new CountDownLatch(2);
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                "testConcurrentThreePhaseCommits");
 
-            class OnFutureComplete extends OnComplete<Object> {
-                private final Class<?> expRespType;
+        class OnFutureComplete extends OnComplete<Object> {
+            private final Class<?> expRespType;
 
-                OnFutureComplete(final Class<?> expRespType) {
-                    this.expRespType = expRespType;
-                }
+            OnFutureComplete(final Class<?> expRespType) {
+                this.expRespType = expRespType;
+            }
 
-                @Override
-                public void onComplete(final Throwable error, final Object resp) {
-                    if(error != null) {
-                        caughtEx.set(new AssertionError(getClass().getSimpleName() + " failure", error));
-                    } else {
-                        try {
-                            assertEquals("Commit response type", expRespType, resp.getClass());
-                            onSuccess(resp);
-                        } catch (Exception e) {
-                            caughtEx.set(e);
-                        }
+            @Override
+            public void onComplete(final Throwable error, final Object resp) {
+                if (error != null) {
+                    caughtEx.set(new AssertionError(getClass().getSimpleName() + " failure", error));
+                } else {
+                    try {
+                        assertEquals("Commit response type", expRespType, resp.getClass());
+                        onSuccess(resp);
+                    } catch (final Exception e) {
+                        caughtEx.set(e);
                     }
                 }
+            }
 
-                void onSuccess(final Object resp) throws Exception {
-                }
+            void onSuccess(final Object resp) throws Exception {
             }
+        }
 
-            class OnCommitFutureComplete extends OnFutureComplete {
-                OnCommitFutureComplete() {
-                    super(CommitTransactionReply.SERIALIZABLE_CLASS);
-                }
+        class OnCommitFutureComplete extends OnFutureComplete {
+            OnCommitFutureComplete() {
+                super(CommitTransactionReply.class);
+            }
 
-                @Override
-                public void onComplete(final Throwable error, final Object resp) {
-                    super.onComplete(error, resp);
-                    commitLatch.countDown();
-                }
+            @Override
+            public void onComplete(final Throwable error, final Object resp) {
+                super.onComplete(error, resp);
+                commitLatch.countDown();
             }
+        }
 
-            class OnCanCommitFutureComplete extends OnFutureComplete {
-                private final String transactionID;
+        class OnCanCommitFutureComplete extends OnFutureComplete {
+            private final TransactionIdentifier transactionID;
 
-                OnCanCommitFutureComplete(final String transactionID) {
-                    super(CanCommitTransactionReply.SERIALIZABLE_CLASS);
-                    this.transactionID = transactionID;
-                }
+            OnCanCommitFutureComplete(final TransactionIdentifier transactionID) {
+                super(CanCommitTransactionReply.class);
+                this.transactionID = transactionID;
+            }
 
-                @Override
-                void onSuccess(final Object resp) throws Exception {
-                    CanCommitTransactionReply canCommitReply =
-                            CanCommitTransactionReply.fromSerializable(resp);
-                    assertEquals("Can commit", true, canCommitReply.getCanCommit());
+            @Override
+            void onSuccess(final Object resp) throws Exception {
+                final CanCommitTransactionReply canCommitReply =
+                        CanCommitTransactionReply.fromSerializable(resp);
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-                    Future<Object> commitFuture = Patterns.ask(shard,
-                            new CommitTransaction(transactionID).toSerializable(), timeout);
-                    commitFuture.onComplete(new OnCommitFutureComplete(), getSystem().dispatcher());
-                }
+                final Future<Object> commitFuture = Patterns.ask(shard,
+                        new CommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), timeout);
+                commitFuture.onComplete(new OnCommitFutureComplete(), getSystem().dispatcher());
             }
+        }
 
-            canCommitFuture1.onComplete(new OnCanCommitFutureComplete(transactionID2),
-                    getSystem().dispatcher());
+        new ShardTestKit(getSystem()) {
+            {
+                waitUntilLeader(shard);
 
-            canCommitFuture2.onComplete(new OnCanCommitFutureComplete(transactionID3),
-                    getSystem().dispatcher());
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                final TransactionIdentifier transactionID3 = nextTransactionId();
 
-            boolean done = commitLatch.await(timeoutSec, TimeUnit.SECONDS);
+                final Map<TransactionIdentifier, CapturingShardDataTreeCohort> cohortMap = setupCohortDecorator(
+                        shard.underlyingActor(), transactionID1, transactionID2, transactionID3);
+                final CapturingShardDataTreeCohort cohort1 = cohortMap.get(transactionID1);
+                final CapturingShardDataTreeCohort cohort2 = cohortMap.get(transactionID2);
+                final CapturingShardDataTreeCohort cohort3 = cohortMap.get(transactionID3);
 
-            if(caughtEx.get() != null) {
-                throw caughtEx.get();
-            }
+                shard.tell(prepareBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                final ReadyTransactionReply readyReply = ReadyTransactionReply
+                        .fromSerializable(expectMsgClass(duration, ReadyTransactionReply.class));
+                assertEquals("Cohort path", shard.path().toString(), readyReply.getCohortPath());
 
-            assertEquals("Commits complete", true, done);
-
-            InOrder inOrder = inOrder(cohort1, cohort2, cohort3);
-            inOrder.verify(cohort1).canCommit();
-            inOrder.verify(cohort1).preCommit();
-            inOrder.verify(cohort1).commit();
-            inOrder.verify(cohort2).canCommit();
-            inOrder.verify(cohort2).preCommit();
-            inOrder.verify(cohort2).commit();
-            inOrder.verify(cohort3).canCommit();
-            inOrder.verify(cohort3).preCommit();
-            inOrder.verify(cohort3).commit();
-
-            // Verify data in the data store.
-
-            NormalizedNode<?, ?> outerList = readStore(shard, TestModel.OUTER_LIST_PATH);
-            assertNotNull(TestModel.OUTER_LIST_QNAME.getLocalName() + " not found", outerList);
-            assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " value is not Iterable",
-                    outerList.getValue() instanceof Iterable);
-            Object entry = ((Iterable<Object>)outerList.getValue()).iterator().next();
-            assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " entry is not MapEntryNode",
-                       entry instanceof MapEntryNode);
-            MapEntryNode mapEntry = (MapEntryNode)entry;
-            Optional<DataContainerChild<? extends PathArgument, ?>> idLeaf =
-                    mapEntry.getChild(new YangInstanceIdentifier.NodeIdentifier(TestModel.ID_QNAME));
-            assertTrue("Missing leaf " + TestModel.ID_QNAME.getLocalName(), idLeaf.isPresent());
-            assertEquals(TestModel.ID_QNAME.getLocalName() + " value", 1, idLeaf.get().getValue());
-
-            verifyLastApplied(shard, 2);
-
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                // Send the CanCommitTransaction message for the first Tx.
 
-    private BatchedModifications newBatchedModifications(String transactionID, YangInstanceIdentifier path,
-            NormalizedNode<?, ?> data, boolean ready) {
-        return newBatchedModifications(transactionID, null, path, data, ready);
-    }
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-    private BatchedModifications newBatchedModifications(String transactionID, String transactionChainID,
-            YangInstanceIdentifier path, NormalizedNode<?, ?> data, boolean ready) {
-        BatchedModifications batched = new BatchedModifications(transactionID, CURRENT_VERSION, transactionChainID);
-        batched.addModification(new WriteModification(path, data));
-        batched.setReady(ready);
-        return batched;
-    }
+                // Ready 2 more Tx's.
 
-    @SuppressWarnings("unchecked")
-    @Test
-    public void testMultipleBatchedModifications() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testMultipleBatchedModifications");
-
-            waitUntilLeader(shard);
-
-            final String transactionID = "tx";
-            FiniteDuration duration = duration("5 seconds");
-
-            final AtomicReference<DOMStoreThreePhaseCommitCohort> mockCohort = new AtomicReference<>();
-            ShardCommitCoordinator.CohortDecorator cohortDecorator = new ShardCommitCoordinator.CohortDecorator() {
-                @Override
-                public DOMStoreThreePhaseCommitCohort decorate(String txID, DOMStoreThreePhaseCommitCohort actual) {
-                    if(mockCohort.get() == null) {
-                        mockCohort.set(createDelegatingMockCohort("cohort", actual));
-                    }
+                shard.tell(prepareBatchedModifications(transactionID2, TestModel.OUTER_LIST_PATH,
+                        ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), false), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-                    return mockCohort.get();
-                }
-            };
+                shard.tell(
+                        prepareBatchedModifications(transactionID3,
+                                YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                                        .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
+                                ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1), false),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Send the CanCommitTransaction message for the next 2 Tx's.
+                // These should get queued and
+                // processed after the first Tx completes.
 
-            shard.underlyingActor().getCommitCoordinator().setCohortDecorator(cohortDecorator);
+                final Future<Object> canCommitFuture1 = Patterns.ask(shard,
+                        new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), timeout);
 
-            // Send a BatchedModifications to start a transaction.
+                final Future<Object> canCommitFuture2 = Patterns.ask(shard,
+                        new CanCommitTransaction(transactionID3, CURRENT_VERSION).toSerializable(), timeout);
 
-            shard.tell(newBatchedModifications(transactionID, TestModel.TEST_PATH,
-                    ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
-            expectMsgClass(duration, BatchedModificationsReply.class);
+                // Send the CommitTransaction message for the first Tx. After it
+                // completes, it should
+                // trigger the 2nd Tx to proceed which should in turn then
+                // trigger the 3rd.
 
-            // Send a couple more BatchedModifications.
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-            shard.tell(newBatchedModifications(transactionID, TestModel.OUTER_LIST_PATH,
-                    ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), false), getRef());
-            expectMsgClass(duration, BatchedModificationsReply.class);
+                // Wait for the next 2 Tx's to complete.
 
-            shard.tell(newBatchedModifications(transactionID, YangInstanceIdentifier.builder(
-                    TestModel.OUTER_LIST_PATH).nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
-                    ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1), true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                canCommitFuture1.onComplete(new OnCanCommitFutureComplete(transactionID2), getSystem().dispatcher());
 
-            // Send the CanCommitTransaction message.
+                canCommitFuture2.onComplete(new OnCanCommitFutureComplete(transactionID3), getSystem().dispatcher());
 
-            shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                final boolean done = commitLatch.await(timeoutSec, TimeUnit.SECONDS);
 
-            // Send the CanCommitTransaction message.
+                if (caughtEx.get() != null) {
+                    Throwables.propagateIfInstanceOf(caughtEx.get(), Exception.class);
+                    Throwables.propagate(caughtEx.get());
+                }
 
-            shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+                assertEquals("Commits complete", true, done);
 
-            InOrder inOrder = inOrder(mockCohort.get());
-            inOrder.verify(mockCohort.get()).canCommit();
-            inOrder.verify(mockCohort.get()).preCommit();
-            inOrder.verify(mockCohort.get()).commit();
+//                final InOrder inOrder = inOrder(cohort1.getCanCommit(), cohort1.getPreCommit(), cohort1.getCommit(),
+//                        cohort2.getCanCommit(), cohort2.getPreCommit(), cohort2.getCommit(), cohort3.getCanCommit(),
+//                        cohort3.getPreCommit(), cohort3.getCommit());
+//                inOrder.verify(cohort1.getCanCommit()).onSuccess(any(Void.class));
+//                inOrder.verify(cohort1.getPreCommit()).onSuccess(any(DataTreeCandidate.class));
+//                inOrder.verify(cohort2.getCanCommit()).onSuccess(any(Void.class));
+//                inOrder.verify(cohort2.getPreCommit()).onSuccess(any(DataTreeCandidate.class));
+//                inOrder.verify(cohort3.getCanCommit()).onSuccess(any(Void.class));
+//                inOrder.verify(cohort3.getPreCommit()).onSuccess(any(DataTreeCandidate.class));
+//                inOrder.verify(cohort1.getCommit()).onSuccess(any(UnsignedLong.class));
+//                inOrder.verify(cohort2.getCommit()).onSuccess(any(UnsignedLong.class));
+//                inOrder.verify(cohort3.getCommit()).onSuccess(any(UnsignedLong.class));
 
-            // Verify data in the data store.
+                // Verify data in the data store.
 
-            NormalizedNode<?, ?> outerList = readStore(shard, TestModel.OUTER_LIST_PATH);
-            assertNotNull(TestModel.OUTER_LIST_QNAME.getLocalName() + " not found", outerList);
-            assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " value is not Iterable",
-                    outerList.getValue() instanceof Iterable);
-            Object entry = ((Iterable<Object>)outerList.getValue()).iterator().next();
-            assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " entry is not MapEntryNode",
-                       entry instanceof MapEntryNode);
-            MapEntryNode mapEntry = (MapEntryNode)entry;
-            Optional<DataContainerChild<? extends PathArgument, ?>> idLeaf =
-                    mapEntry.getChild(new YangInstanceIdentifier.NodeIdentifier(TestModel.ID_QNAME));
-            assertTrue("Missing leaf " + TestModel.ID_QNAME.getLocalName(), idLeaf.isPresent());
-            assertEquals(TestModel.ID_QNAME.getLocalName() + " value", 1, idLeaf.get().getValue());
+                verifyOuterListEntry(shard, 1);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                verifyLastApplied(shard, 2);
+            }
+        };
     }
 
     @Test
-    public void testBatchedModificationsOnTransactionChain() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testBatchedModificationsOnTransactionChain");
-
-            waitUntilLeader(shard);
-
-            String transactionChainID = "txChain";
-            String transactionID1 = "tx1";
-            String transactionID2 = "tx2";
+    public void testBatchedModificationsWithNoCommitOnReady() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testBatchedModificationsWithNoCommitOnReady");
 
-            FiniteDuration duration = duration("5 seconds");
+                waitUntilLeader(shard);
 
-            // Send a BatchedModifications to start a chained write transaction and ready it.
+                final TransactionIdentifier transactionID = nextTransactionId();
+                final FiniteDuration duration = duration("5 seconds");
 
-            ContainerNode containerNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
-            YangInstanceIdentifier path = TestModel.TEST_PATH;
-            shard.tell(newBatchedModifications(transactionID1, transactionChainID, path,
-                    containerNode, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Send a BatchedModifications to start a transaction.
 
-            // Create a read Tx on the same chain.
+                shard.tell(newBatchedModifications(transactionID, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false, false, 1), getRef());
+                expectMsgClass(duration, BatchedModificationsReply.class);
 
-            shard.tell(new CreateTransaction(transactionID2, TransactionProxy.TransactionType.READ_ONLY.ordinal() ,
-                    transactionChainID).toSerializable(), getRef());
+                // Send a couple more BatchedModifications.
 
-            CreateTransactionReply createReply = expectMsgClass(duration("3 seconds"), CreateTransactionReply.class);
+                shard.tell(
+                        newBatchedModifications(transactionID, TestModel.OUTER_LIST_PATH,
+                                ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), false, false, 2),
+                        getRef());
+                expectMsgClass(duration, BatchedModificationsReply.class);
 
-            getSystem().actorSelection(createReply.getTransactionActorPath()).tell(new ReadData(path), getRef());
-            ReadDataReply readReply = expectMsgClass(duration("3 seconds"), ReadDataReply.class);
-            assertEquals("Read node", containerNode, readReply.getNormalizedNode());
+                shard.tell(newBatchedModifications(transactionID,
+                        YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                                .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
+                        ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1), true, false, 3),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            // Commit the write transaction.
+                // Send the CanCommitTransaction message.
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                shard.tell(new CanCommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-            shard.tell(new CommitTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+                // Send the CommitTransaction message.
 
-            // Verify data in the data store.
+                shard.tell(new CommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-            NormalizedNode<?, ?> actualNode = readStore(shard, path);
-            assertEquals("Stored node", containerNode, actualNode);
+                // Verify data in the data store.
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                verifyOuterListEntry(shard, 1);
+            }
+        };
     }
 
     @Test
-    public void testOnBatchedModificationsWhenNotLeader() {
-        final AtomicBoolean overrideLeaderCalls = new AtomicBoolean();
-        new ShardTestKit(getSystem()) {{
-            Creator<Shard> creator = new Creator<Shard>() {
-                @Override
-                public Shard create() throws Exception {
-                    return new Shard(shardID, Collections.<String,String>emptyMap(),
-                            newDatastoreContext(), SCHEMA_CONTEXT) {
-                        @Override
-                        protected boolean isLeader() {
-                            return overrideLeaderCalls.get() ? false : super.isLeader();
-                        }
-
-                        @Override
-                        protected ActorSelection getLeader() {
-                            return overrideLeaderCalls.get() ? getSystem().actorSelection(getRef().path()) :
-                                super.getLeader();
-                        }
-                    };
-                }
-            };
-
-            TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    Props.create(new DelegatingShardCreator(creator)), "testOnBatchedModificationsWhenNotLeader");
-
-            waitUntilLeader(shard);
-
-            overrideLeaderCalls.set(true);
-
-            BatchedModifications batched = new BatchedModifications("tx", DataStoreVersions.CURRENT_VERSION, "");
-
-            shard.tell(batched, ActorRef.noSender());
-
-            expectMsgEquals(batched);
+    public void testBatchedModificationsWithCommitOnReady() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testBatchedModificationsWithCommitOnReady");
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                waitUntilLeader(shard);
 
-    @Test
-    public void testCommitWithPersistenceDisabled() throws Throwable {
-        dataStoreContextBuilder.persistent(false);
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testCommitWithPersistenceDisabled");
+                final TransactionIdentifier transactionID = nextTransactionId();
+                final FiniteDuration duration = duration("5 seconds");
 
-            waitUntilLeader(shard);
+                // Send a BatchedModifications to start a transaction.
 
-            InMemoryDOMDataStore dataStore = shard.underlyingActor().getDataStore();
+                shard.tell(newBatchedModifications(transactionID, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false, false, 1), getRef());
+                expectMsgClass(duration, BatchedModificationsReply.class);
 
-            // Setup a simulated transactions with a mock cohort.
+                // Send a couple more BatchedModifications.
 
-            String transactionID = "tx";
-            MutableCompositeModification modification = new MutableCompositeModification();
-            NormalizedNode<?, ?> containerNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
-            DOMStoreThreePhaseCommitCohort cohort = setupMockWriteTransaction("cohort", dataStore,
-                    TestModel.TEST_PATH, containerNode, modification);
+                shard.tell(newBatchedModifications(transactionID, TestModel.OUTER_LIST_PATH,
+                                ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), false, false, 2),
+                        getRef());
+                expectMsgClass(duration, BatchedModificationsReply.class);
 
-            FiniteDuration duration = duration("5 seconds");
+                shard.tell(newBatchedModifications(transactionID,
+                        YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                                .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
+                        ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1), true, true, 3),
+                        getRef());
 
-            // Simulate the ForwardedReadyTransaction messages that would be sent
-            // by the ShardTransaction.
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                    cohort, modification, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Verify data in the data store.
 
-            // Send the CanCommitTransaction message.
+                verifyOuterListEntry(shard, 1);
+            }
+        };
+    }
 
-            shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+    @Test(expected = IllegalStateException.class)
+    public void testBatchedModificationsReadyWithIncorrectTotalMessageCount() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testBatchedModificationsReadyWithIncorrectTotalMessageCount");
 
-            // Send the CanCommitTransaction message.
+                waitUntilLeader(shard);
 
-            shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+                final TransactionIdentifier transactionID = nextTransactionId();
+                final BatchedModifications batched = new BatchedModifications(transactionID,
+                        DataStoreVersions.CURRENT_VERSION);
+                batched.setReady(true);
+                batched.setTotalMessagesSent(2);
 
-            InOrder inOrder = inOrder(cohort);
-            inOrder.verify(cohort).canCommit();
-            inOrder.verify(cohort).preCommit();
-            inOrder.verify(cohort).commit();
+                shard.tell(batched, getRef());
 
-            NormalizedNode<?, ?> actualNode = readStore(shard, TestModel.TEST_PATH);
-            assertEquals(TestModel.TEST_QNAME.getLocalName(), containerNode, actualNode);
+                final Failure failure = expectMsgClass(duration("5 seconds"), akka.actor.Status.Failure.class);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                if (failure != null) {
+                    Throwables.propagateIfInstanceOf(failure.cause(), Exception.class);
+                    Throwables.propagate(failure.cause());
+                }
+            }
+        };
     }
 
     @Test
-    public void testCommitWhenTransactionHasNoModifications(){
-        // Note that persistence is enabled which would normally result in the entry getting written to the journal
-        // but here that need not happen
+    public void testBatchedModificationsWithOperationFailure() throws Exception {
         new ShardTestKit(getSystem()) {
             {
-                final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
                         newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                        "testCommitWhenTransactionHasNoModifications");
+                        "testBatchedModificationsWithOperationFailure");
 
                 waitUntilLeader(shard);
 
-                String transactionID = "tx1";
-                MutableCompositeModification modification = new MutableCompositeModification();
-                DOMStoreThreePhaseCommitCohort cohort = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).canCommit();
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).preCommit();
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).commit();
-
-                FiniteDuration duration = duration("5 seconds");
-
-                // Simulate the ForwardedReadyTransaction messages that would be sent
-                // by the ShardTransaction.
-
-                shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                        cohort, modification, true), getRef());
-                expectMsgClass(duration, ReadyTransactionReply.class);
-
-                // Send the CanCommitTransaction message.
+                // Test merge with invalid data. An exception should occur when
+                // the merge is applied. Note that
+                // write will not validate the children for performance reasons.
 
-                shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-                CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                        expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-                assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                final TransactionIdentifier transactionID = nextTransactionId();
 
-                shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-                expectMsgClass(duration, ThreePhaseCommitCohortMessages.CommitTransactionReply.class);
+                final ContainerNode invalidData = ImmutableContainerNodeBuilder.create()
+                        .withNodeIdentifier(new YangInstanceIdentifier.NodeIdentifier(TestModel.TEST_QNAME))
+                        .withChild(ImmutableNodes.leafNode(TestModel.JUNK_QNAME, "junk")).build();
 
-                InOrder inOrder = inOrder(cohort);
-                inOrder.verify(cohort).canCommit();
-                inOrder.verify(cohort).preCommit();
-                inOrder.verify(cohort).commit();
+                BatchedModifications batched = new BatchedModifications(transactionID, CURRENT_VERSION);
+                batched.addModification(new MergeModification(TestModel.TEST_PATH, invalidData));
+                shard.tell(batched, getRef());
+                Failure failure = expectMsgClass(duration("5 seconds"), akka.actor.Status.Failure.class);
 
-                // Use MBean for verification
-                // Committed transaction count should increase as usual
-                assertEquals(1,shard.underlyingActor().getShardMBean().getCommittedTransactionsCount());
+                final Throwable cause = failure.cause();
 
-                // Commit index should not advance because this does not go into the journal
-                assertEquals(-1, shard.underlyingActor().getShardMBean().getCommitIndex());
+                batched = new BatchedModifications(transactionID, DataStoreVersions.CURRENT_VERSION);
+                batched.setReady(true);
+                batched.setTotalMessagesSent(2);
 
-                shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                shard.tell(batched, getRef());
 
+                failure = expectMsgClass(duration("5 seconds"), akka.actor.Status.Failure.class);
+                assertEquals("Failure cause", cause, failure.cause());
             }
         };
     }
 
     @Test
-    public void testCommitWhenTransactionHasModifications(){
+    public void testBatchedModificationsOnTransactionChain() throws Exception {
         new ShardTestKit(getSystem()) {
             {
-                final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
                         newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                        "testCommitWhenTransactionHasModifications");
+                        "testBatchedModificationsOnTransactionChain");
 
                 waitUntilLeader(shard);
 
-                String transactionID = "tx1";
-                MutableCompositeModification modification = new MutableCompositeModification();
-                modification.addModification(new DeleteModification(YangInstanceIdentifier.builder().build()));
-                DOMStoreThreePhaseCommitCohort cohort = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).canCommit();
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).preCommit();
-                doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).commit();
+                final LocalHistoryIdentifier historyId = nextHistoryId();
+                final TransactionIdentifier transactionID1 = new TransactionIdentifier(historyId, 0);
+                final TransactionIdentifier transactionID2 = new TransactionIdentifier(historyId, 1);
 
-                FiniteDuration duration = duration("5 seconds");
+                final FiniteDuration duration = duration("5 seconds");
 
-                // Simulate the ForwardedReadyTransaction messages that would be sent
-                // by the ShardTransaction.
+                // Send a BatchedModifications to start a chained write
+                // transaction and ready it.
 
-                shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                        cohort, modification, true), getRef());
+                final ContainerNode containerNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                shard.tell(newBatchedModifications(transactionID1, path, containerNode, true, false, 1), getRef());
                 expectMsgClass(duration, ReadyTransactionReply.class);
 
-                // Send the CanCommitTransaction message.
+                // Create a read Tx on the same chain.
 
-                shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-                CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                        expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-                assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                shard.tell(new CreateTransaction(transactionID2, TransactionType.READ_ONLY.ordinal(),
+                        DataStoreVersions.CURRENT_VERSION).toSerializable(), getRef());
 
-                shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-                expectMsgClass(duration, ThreePhaseCommitCohortMessages.CommitTransactionReply.class);
+                final CreateTransactionReply createReply = expectMsgClass(duration("3 seconds"),
+                        CreateTransactionReply.class);
 
-                InOrder inOrder = inOrder(cohort);
-                inOrder.verify(cohort).canCommit();
-                inOrder.verify(cohort).preCommit();
-                inOrder.verify(cohort).commit();
+                getSystem().actorSelection(createReply.getTransactionPath())
+                        .tell(new ReadData(path, DataStoreVersions.CURRENT_VERSION), getRef());
+                final ReadDataReply readReply = expectMsgClass(duration("3 seconds"), ReadDataReply.class);
+                assertEquals("Read node", containerNode, readReply.getNormalizedNode());
 
-                // Use MBean for verification
-                // Committed transaction count should increase as usual
-                assertEquals(1, shard.underlyingActor().getShardMBean().getCommittedTransactionsCount());
+                // Commit the write transaction.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-                // Commit index should advance as we do not have an empty modification
-                assertEquals(0, shard.underlyingActor().getShardMBean().getCommitIndex());
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-                shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                // Verify data in the data store.
 
+                final NormalizedNode<?, ?> actualNode = readStore(shard, path);
+                assertEquals("Stored node", containerNode, actualNode);
             }
         };
     }
 
     @Test
-    public void testCommitPhaseFailure() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testCommitPhaseFailure");
+    public void testOnBatchedModificationsWhenNotLeader() {
+        final AtomicBoolean overrideLeaderCalls = new AtomicBoolean();
+        new ShardTestKit(getSystem()) {
+            {
+                final Creator<Shard> creator = new Creator<Shard>() {
+                    private static final long serialVersionUID = 1L;
+
+                    @Override
+                    public Shard create() throws Exception {
+                        return new Shard(newShardBuilder()) {
+                            @Override
+                            protected boolean isLeader() {
+                                return overrideLeaderCalls.get() ? false : super.isLeader();
+                            }
+
+                            @Override
+                            public ActorSelection getLeader() {
+                                return overrideLeaderCalls.get() ? getSystem().actorSelection(getRef().path())
+                                        : super.getLeader();
+                            }
+                        };
+                    }
+                };
 
-            waitUntilLeader(shard);
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(Props
+                        .create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testOnBatchedModificationsWhenNotLeader");
 
-         // Setup 2 simulated transactions with mock cohorts. The first one fails in the
-            // commit phase.
+                waitUntilLeader(shard);
 
-            String transactionID1 = "tx1";
-            MutableCompositeModification modification1 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort1 = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-            doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort1).canCommit();
-            doReturn(Futures.immediateFuture(null)).when(cohort1).preCommit();
-            doReturn(Futures.immediateFailedFuture(new IllegalStateException("mock"))).when(cohort1).commit();
+                overrideLeaderCalls.set(true);
 
-            String transactionID2 = "tx2";
-            MutableCompositeModification modification2 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort2 = mock(DOMStoreThreePhaseCommitCohort.class, "cohort2");
-            doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort2).canCommit();
+                final BatchedModifications batched = new BatchedModifications(nextTransactionId(),
+                        DataStoreVersions.CURRENT_VERSION);
 
-            FiniteDuration duration = duration("5 seconds");
-            final Timeout timeout = new Timeout(duration);
+                shard.tell(batched, ActorRef.noSender());
 
-            // Simulate the ForwardedReadyTransaction messages that would be sent
-            // by the ShardTransaction.
+                expectMsgEquals(batched);
+            }
+        };
+    }
 
-            shard.tell(new ForwardedReadyTransaction(transactionID1, CURRENT_VERSION,
-                    cohort1, modification1, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+    @Test
+    public void testTransactionMessagesWithNoLeader() {
+        new ShardTestKit(getSystem()) {
+            {
+                dataStoreContextBuilder.customRaftPolicyImplementation(DisableElectionsRaftPolicy.class.getName())
+                        .shardHeartbeatIntervalInMillis(50).shardElectionTimeoutFactor(1);
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testTransactionMessagesWithNoLeader");
 
-            shard.tell(new ForwardedReadyTransaction(transactionID2, CURRENT_VERSION,
-                    cohort2, modification2, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                waitUntilNoLeader(shard);
 
-            // Send the CanCommitTransaction message for the first Tx.
+                final TransactionIdentifier txId = nextTransactionId();
+                shard.tell(new BatchedModifications(txId, DataStoreVersions.CURRENT_VERSION), getRef());
+                Failure failure = expectMsgClass(Failure.class);
+                assertEquals("Failure cause type", NoShardLeaderException.class, failure.cause().getClass());
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                shard.tell(prepareForwardedReadyTransaction(shard, txId, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true), getRef());
+                failure = expectMsgClass(Failure.class);
+                assertEquals("Failure cause type", NoShardLeaderException.class, failure.cause().getClass());
 
-            // Send the CanCommitTransaction message for the 2nd Tx. This should get queued and
-            // processed after the first Tx completes.
+                shard.tell(new ReadyLocalTransaction(txId, mock(DataTreeModification.class), true), getRef());
+                failure = expectMsgClass(Failure.class);
+                assertEquals("Failure cause type", NoShardLeaderException.class, failure.cause().getClass());
+            }
+        };
+    }
 
-            Future<Object> canCommitFuture = Patterns.ask(shard,
-                    new CanCommitTransaction(transactionID2).toSerializable(), timeout);
+    @Test
+    public void testReadyWithReadWriteImmediateCommit() throws Exception {
+        testReadyWithImmediateCommit(true);
+    }
 
-            // Send the CommitTransaction message for the first Tx. This should send back an error
-            // and trigger the 2nd Tx to proceed.
+    @Test
+    public void testReadyWithWriteOnlyImmediateCommit() throws Exception {
+        testReadyWithImmediateCommit(false);
+    }
 
-            shard.tell(new CommitTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, akka.actor.Status.Failure.class);
+    private void testReadyWithImmediateCommit(final boolean readWrite) throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testReadyWithImmediateCommit-" + readWrite);
 
-            // Wait for the 2nd Tx to complete the canCommit phase.
+                waitUntilLeader(shard);
 
-            final CountDownLatch latch = new CountDownLatch(1);
-            canCommitFuture.onComplete(new OnComplete<Object>() {
-                @Override
-                public void onComplete(final Throwable t, final Object resp) {
-                    latch.countDown();
+                final TransactionIdentifier transactionID = nextTransactionId();
+                final NormalizedNode<?, ?> containerNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                if (readWrite) {
+                    shard.tell(prepareForwardedReadyTransaction(shard, transactionID, TestModel.TEST_PATH,
+                            containerNode, true), getRef());
+                } else {
+                    shard.tell(prepareBatchedModifications(transactionID, TestModel.TEST_PATH, containerNode, true),
+                            getRef());
                 }
-            }, getSystem().dispatcher());
-
-            assertEquals("2nd CanCommit complete", true, latch.await(5, TimeUnit.SECONDS));
 
-            InOrder inOrder = inOrder(cohort1, cohort2);
-            inOrder.verify(cohort1).canCommit();
-            inOrder.verify(cohort1).preCommit();
-            inOrder.verify(cohort1).commit();
-            inOrder.verify(cohort2).canCommit();
+                expectMsgClass(duration("5 seconds"), CommitTransactionReply.class);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                final NormalizedNode<?, ?> actualNode = readStore(shard, TestModel.TEST_PATH);
+                assertEquals(TestModel.TEST_QNAME.getLocalName(), containerNode, actualNode);
+            }
+        };
     }
 
     @Test
-    public void testPreCommitPhaseFailure() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testPreCommitPhaseFailure");
+    public void testReadyLocalTransactionWithImmediateCommit() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testReadyLocalTransactionWithImmediateCommit");
 
-            waitUntilLeader(shard);
+                waitUntilLeader(shard);
 
-            String transactionID = "tx1";
-            MutableCompositeModification modification = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-            doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).canCommit();
-            doReturn(Futures.immediateFailedFuture(new IllegalStateException("mock"))).when(cohort).preCommit();
+                final ShardDataTree dataStore = shard.underlyingActor().getDataStore();
 
-            FiniteDuration duration = duration("5 seconds");
+                final DataTreeModification modification = dataStore.newModification();
 
-            // Simulate the ForwardedReadyTransaction messages that would be sent
-            // by the ShardTransaction.
+                final ContainerNode writeData = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                new WriteModification(TestModel.TEST_PATH, writeData).apply(modification);
+                final MapNode mergeData = ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build();
+                new MergeModification(TestModel.OUTER_LIST_PATH, mergeData).apply(modification);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                    cohort, modification, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                final TransactionIdentifier txId = nextTransactionId();
+                modification.ready();
+                final ReadyLocalTransaction readyMessage = new ReadyLocalTransaction(txId, modification, true);
 
-            // Send the CanCommitTransaction message.
+                shard.tell(readyMessage, getRef());
 
-            shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                expectMsgClass(CommitTransactionReply.class);
 
-            // Send the CommitTransaction message. This should send back an error
-            // for preCommit failure.
+                final NormalizedNode<?, ?> actualNode = readStore(shard, TestModel.OUTER_LIST_PATH);
+                assertEquals(TestModel.OUTER_LIST_QNAME.getLocalName(), mergeData, actualNode);
+            }
+        };
+    }
 
-            shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-            expectMsgClass(duration, akka.actor.Status.Failure.class);
+    @Test
+    public void testReadyLocalTransactionWithThreePhaseCommit() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testReadyLocalTransactionWithThreePhaseCommit");
 
-            InOrder inOrder = inOrder(cohort);
-            inOrder.verify(cohort).canCommit();
-            inOrder.verify(cohort).preCommit();
+                waitUntilLeader(shard);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                final ShardDataTree dataStore = shard.underlyingActor().getDataStore();
 
-    @Test
-    public void testCanCommitPhaseFailure() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testCanCommitPhaseFailure");
+                final DataTreeModification modification = dataStore.newModification();
 
-            waitUntilLeader(shard);
+                final ContainerNode writeData = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                new WriteModification(TestModel.TEST_PATH, writeData).apply(modification);
+                final MapNode mergeData = ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build();
+                new MergeModification(TestModel.OUTER_LIST_PATH, mergeData).apply(modification);
 
-            final FiniteDuration duration = duration("5 seconds");
+                final TransactionIdentifier txId = nextTransactionId();
+                modification.ready();
+                final ReadyLocalTransaction readyMessage = new ReadyLocalTransaction(txId, modification, false);
 
-            String transactionID = "tx1";
-            MutableCompositeModification modification = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-            doReturn(Futures.immediateFailedFuture(new IllegalStateException("mock"))).when(cohort).canCommit();
+                shard.tell(readyMessage, getRef());
 
-            // Simulate the ForwardedReadyTransaction messages that would be sent
-            // by the ShardTransaction.
+                expectMsgClass(ReadyTransactionReply.class);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                    cohort, modification, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Send the CanCommitTransaction message.
+
+                shard.tell(new CanCommitTransaction(txId, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-            // Send the CanCommitTransaction message.
+                // Send the CanCommitTransaction message.
 
-            shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-            expectMsgClass(duration, akka.actor.Status.Failure.class);
+                shard.tell(new CommitTransaction(txId, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(CommitTransactionReply.class);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                final NormalizedNode<?, ?> actualNode = readStore(shard, TestModel.OUTER_LIST_PATH);
+                assertEquals(TestModel.OUTER_LIST_QNAME.getLocalName(), mergeData, actualNode);
+            }
+        };
     }
 
     @Test
-    public void testAbortBeforeFinishCommit() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testAbortBeforeFinishCommit");
-
-            waitUntilLeader(shard);
-
-            final FiniteDuration duration = duration("5 seconds");
-            InMemoryDOMDataStore dataStore = shard.underlyingActor().getDataStore();
-
-            final String transactionID = "tx1";
-            Function<DOMStoreThreePhaseCommitCohort,ListenableFuture<Void>> preCommit =
-                          new Function<DOMStoreThreePhaseCommitCohort,ListenableFuture<Void>>() {
-                @Override
-                public ListenableFuture<Void> apply(final DOMStoreThreePhaseCommitCohort cohort) {
-                    ListenableFuture<Void> preCommitFuture = cohort.preCommit();
-
-                    // Simulate an AbortTransaction message occurring during replication, after
-                    // persisting and before finishing the commit to the in-memory store.
-                    // We have no followers so due to optimizations in the RaftActor, it does not
-                    // attempt replication and thus we can't send an AbortTransaction message b/c
-                    // it would be processed too late after CommitTransaction completes. So we'll
-                    // simulate an AbortTransaction message occurring during replication by calling
-                    // the shard directly.
-                    //
-                    shard.underlyingActor().doAbortTransaction(transactionID, null);
-
-                    return preCommitFuture;
-                }
-            };
+    public void testReadWriteCommitWithPersistenceDisabled() throws Exception {
+        dataStoreContextBuilder.persistent(false);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testCommitWithPersistenceDisabled");
 
-            MutableCompositeModification modification = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort = setupMockWriteTransaction("cohort1", dataStore,
-                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME),
-                    modification, preCommit);
+                waitUntilLeader(shard);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID, CURRENT_VERSION,
-                    cohort, modification, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Setup a simulated transactions with a mock cohort.
 
-            shard.tell(new CanCommitTransaction(transactionID).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                final FiniteDuration duration = duration("5 seconds");
 
-            shard.tell(new CommitTransaction(transactionID).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+                final TransactionIdentifier transactionID = nextTransactionId();
+                final NormalizedNode<?, ?> containerNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                shard.tell(prepareBatchedModifications(transactionID, TestModel.TEST_PATH, containerNode, false),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            NormalizedNode<?, ?> node = readStore(shard, TestModel.TEST_PATH);
+                // Send the CanCommitTransaction message.
 
-            // Since we're simulating an abort occurring during replication and before finish commit,
-            // the data should still get written to the in-memory store since we've gotten past
-            // canCommit and preCommit and persisted the data.
-            assertNotNull(TestModel.TEST_QNAME.getLocalName() + " not found", node);
+                shard.tell(new CanCommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
-    }
+                // Send the CanCommitTransaction message.
+
+                shard.tell(new CommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                final NormalizedNode<?, ?> actualNode = readStore(shard, TestModel.TEST_PATH);
+                assertEquals(TestModel.TEST_QNAME.getLocalName(), containerNode, actualNode);
+            }
+        };
+    }
 
     @Test
-    public void testTransactionCommitTimeout() throws Throwable {
-        dataStoreContextBuilder.shardTransactionCommitTimeoutInSeconds(1);
+    public void testReadWriteCommitWhenTransactionHasModifications() throws Exception {
+        testCommitWhenTransactionHasModifications(true);
+    }
+
+    @Test
+    public void testWriteOnlyCommitWhenTransactionHasModifications() throws Exception {
+        testCommitWhenTransactionHasModifications(false);
+    }
+
+    private void testCommitWhenTransactionHasModifications(final boolean readWrite) throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TipProducingDataTree dataTree = createDelegatingMockDataTree();
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().dataTree(dataTree).props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testCommitWhenTransactionHasModifications-" + readWrite);
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+                final TransactionIdentifier transactionID = nextTransactionId();
+
+                if (readWrite) {
+                    shard.tell(prepareForwardedReadyTransaction(shard, transactionID, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                } else {
+                    shard.tell(prepareBatchedModifications(transactionID, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                }
+
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testTransactionCommitTimeout");
+                // Send the CanCommitTransaction message.
 
-            waitUntilLeader(shard);
+                shard.tell(new CanCommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-            final FiniteDuration duration = duration("5 seconds");
+                shard.tell(new CommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-            InMemoryDOMDataStore dataStore = shard.underlyingActor().getDataStore();
+                final InOrder inOrder = inOrder(dataTree);
+                inOrder.verify(dataTree).validate(any(DataTreeModification.class));
+                inOrder.verify(dataTree).prepare(any(DataTreeModification.class));
+                inOrder.verify(dataTree).commit(any(DataTreeCandidate.class));
 
-            writeToStore(shard, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
-            writeToStore(shard, TestModel.OUTER_LIST_PATH,
-                    ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build());
+                shard.tell(Shard.GET_SHARD_MBEAN_MESSAGE, getRef());
+                final ShardStats shardStats = expectMsgClass(duration, ShardStats.class);
 
-            // Create 1st Tx - will timeout
+                // Use MBean for verification
+                // Committed transaction count should increase as usual
+                assertEquals(1, shardStats.getCommittedTransactionsCount());
 
-            String transactionID1 = "tx1";
-            MutableCompositeModification modification1 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort1 = setupMockWriteTransaction("cohort1", dataStore,
-                    YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
-                        .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
-                    ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1),
-                    modification1);
+                // Commit index should advance as we do not have an empty
+                // modification
+                assertEquals(0, shardStats.getCommitIndex());
+            }
+        };
+    }
 
-            // Create 2nd Tx
+    @Test
+    public void testCommitPhaseFailure() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TipProducingDataTree dataTree = createDelegatingMockDataTree();
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().dataTree(dataTree).props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testCommitPhaseFailure");
 
-            String transactionID2 = "tx3";
-            MutableCompositeModification modification2 = new MutableCompositeModification();
-            YangInstanceIdentifier listNodePath = YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
-                .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2).build();
-            DOMStoreThreePhaseCommitCohort cohort2 = setupMockWriteTransaction("cohort3", dataStore,
-                    listNodePath,
-                    ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2),
-                    modification2);
+                waitUntilLeader(shard);
 
-            // Ready the Tx's
+                final FiniteDuration duration = duration("5 seconds");
+                final Timeout timeout = new Timeout(duration);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID1, CURRENT_VERSION,
-                    cohort1, modification1, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Setup 2 simulated transactions with mock cohorts. The first
+                // one fails in the
+                // commit phase.
 
-            shard.tell(new ForwardedReadyTransaction(transactionID2, CURRENT_VERSION,
-                    cohort2, modification2, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                doThrow(new RuntimeException("mock commit failure")).when(dataTree)
+                        .commit(any(DataTreeCandidate.class));
 
-            // canCommit 1st Tx. We don't send the commit so it should timeout.
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Send the CanCommitTransaction message for the first Tx.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
+
+                // Send the CanCommitTransaction message for the 2nd Tx. This
+                // should get queued and
+                // processed after the first Tx completes.
+
+                final Future<Object> canCommitFuture = Patterns.ask(shard,
+                        new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), timeout);
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS);
+                // Send the CommitTransaction message for the first Tx. This
+                // should send back an error
+                // and trigger the 2nd Tx to proceed.
 
-            // canCommit the 2nd Tx - it should complete after the 1st Tx times out.
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, akka.actor.Status.Failure.class);
 
-            shard.tell(new CanCommitTransaction(transactionID2).toSerializable(), getRef());
-            expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS);
+                // Wait for the 2nd Tx to complete the canCommit phase.
+
+                final CountDownLatch latch = new CountDownLatch(1);
+                canCommitFuture.onComplete(new OnComplete<Object>() {
+                    @Override
+                    public void onComplete(final Throwable failure, final Object resp) {
+                        latch.countDown();
+                    }
+                }, getSystem().dispatcher());
 
-            // Commit the 2nd Tx.
+                assertEquals("2nd CanCommit complete", true, latch.await(5, TimeUnit.SECONDS));
 
-            shard.tell(new CommitTransaction(transactionID2).toSerializable(), getRef());
-            expectMsgClass(duration, CommitTransactionReply.SERIALIZABLE_CLASS);
+                final InOrder inOrder = inOrder(dataTree);
+                inOrder.verify(dataTree).validate(any(DataTreeModification.class));
+                inOrder.verify(dataTree).prepare(any(DataTreeModification.class));
 
-            NormalizedNode<?, ?> node = readStore(shard, listNodePath);
-            assertNotNull(listNodePath + " not found", node);
+                // FIXME: this invocation is done on the result of validate(). To test it, we need to make sure mock
+                //        validate performs wrapping and we capture that mock
+                // inOrder.verify(dataTree).validate(any(DataTreeModification.class));
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                inOrder.verify(dataTree).commit(any(DataTreeCandidate.class));
+            }
+        };
     }
 
     @Test
-    public void testTransactionCommitQueueCapacityExceeded() throws Throwable {
-        dataStoreContextBuilder.shardTransactionCommitQueueCapacity(1);
+    public void testPreCommitPhaseFailure() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TipProducingDataTree dataTree = createDelegatingMockDataTree();
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().dataTree(dataTree).props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testPreCommitPhaseFailure");
 
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testTransactionCommitQueueCapacityExceeded");
+                waitUntilLeader(shard);
 
-            waitUntilLeader(shard);
+                final FiniteDuration duration = duration("5 seconds");
+                final Timeout timeout = new Timeout(duration);
 
-            final FiniteDuration duration = duration("5 seconds");
+                doThrow(new RuntimeException("mock preCommit failure")).when(dataTree)
+                        .prepare(any(DataTreeModification.class));
 
-            InMemoryDOMDataStore dataStore = shard.underlyingActor().getDataStore();
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Send the CanCommitTransaction message for the first Tx.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
 
-            String transactionID1 = "tx1";
-            MutableCompositeModification modification1 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort1 = setupMockWriteTransaction("cohort1", dataStore,
-                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME), modification1);
+                // Send the CanCommitTransaction message for the 2nd Tx. This
+                // should get queued and
+                // processed after the first Tx completes.
 
-            String transactionID2 = "tx2";
-            MutableCompositeModification modification2 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort2 = setupMockWriteTransaction("cohort2", dataStore,
-                    TestModel.OUTER_LIST_PATH,
-                    ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(),
-                    modification2);
+                final Future<Object> canCommitFuture = Patterns.ask(shard,
+                        new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), timeout);
 
-            String transactionID3 = "tx3";
-            MutableCompositeModification modification3 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort3 = setupMockWriteTransaction("cohort3", dataStore,
-                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME), modification3);
+                // Send the CommitTransaction message for the first Tx. This
+                // should send back an error
+                // and trigger the 2nd Tx to proceed.
 
-            // Ready the Tx's
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, akka.actor.Status.Failure.class);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID1, CURRENT_VERSION,
-                    cohort1, modification1, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Wait for the 2nd Tx to complete the canCommit phase.
+
+                final CountDownLatch latch = new CountDownLatch(1);
+                canCommitFuture.onComplete(new OnComplete<Object>() {
+                    @Override
+                    public void onComplete(final Throwable failure, final Object resp) {
+                        latch.countDown();
+                    }
+                }, getSystem().dispatcher());
+
+                assertEquals("2nd CanCommit complete", true, latch.await(5, TimeUnit.SECONDS));
+
+                final InOrder inOrder = inOrder(dataTree);
+                inOrder.verify(dataTree).validate(any(DataTreeModification.class));
+                inOrder.verify(dataTree).prepare(any(DataTreeModification.class));
+                inOrder.verify(dataTree).validate(any(DataTreeModification.class));
+            }
+        };
+    }
+
+    @Test
+    public void testCanCommitPhaseFailure() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TipProducingDataTree dataTree = createDelegatingMockDataTree();
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().dataTree(dataTree).props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testCanCommitPhaseFailure");
 
-            shard.tell(new ForwardedReadyTransaction(transactionID2, CURRENT_VERSION,
-                    cohort2, modification2, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                waitUntilLeader(shard);
 
-            shard.tell(new ForwardedReadyTransaction(transactionID3, CURRENT_VERSION,
-                    cohort3, modification3, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                final FiniteDuration duration = duration("5 seconds");
+                final TransactionIdentifier transactionID1 = nextTransactionId();
 
-            // canCommit 1st Tx.
+                doThrow(new DataValidationFailedException(YangInstanceIdentifier.EMPTY, "mock canCommit failure"))
+                        .doNothing().when(dataTree).validate(any(DataTreeModification.class));
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS);
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            // canCommit the 2nd Tx - it should get queued.
+                // Send the CanCommitTransaction message.
 
-            shard.tell(new CanCommitTransaction(transactionID2).toSerializable(), getRef());
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, akka.actor.Status.Failure.class);
 
-            // canCommit the 3rd Tx - should exceed queue capacity and fail.
+                // Send another can commit to ensure the failed one got cleaned
+                // up.
 
-            shard.tell(new CanCommitTransaction(transactionID3).toSerializable(), getRef());
-            expectMsgClass(duration, akka.actor.Status.Failure.class);
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                shard.tell(new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+                final CanCommitTransactionReply reply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(CanCommitTransactionReply.class));
+                assertEquals("getCanCommit", true, reply.getCanCommit());
+            }
+        };
     }
 
     @Test
-    public void testCanCommitBeforeReadyFailure() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testCanCommitBeforeReadyFailure");
+    public void testImmediateCommitWithCanCommitPhaseFailure() throws Exception {
+        testImmediateCommitWithCanCommitPhaseFailure(true);
+        testImmediateCommitWithCanCommitPhaseFailure(false);
+    }
+
+    private void testImmediateCommitWithCanCommitPhaseFailure(final boolean readWrite) throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TipProducingDataTree dataTree = createDelegatingMockDataTree();
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().dataTree(dataTree).props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testImmediateCommitWithCanCommitPhaseFailure-" + readWrite);
 
-            shard.tell(new CanCommitTransaction("tx").toSerializable(), getRef());
-            expectMsgClass(duration("5 seconds"), akka.actor.Status.Failure.class);
+                waitUntilLeader(shard);
+
+                doThrow(new DataValidationFailedException(YangInstanceIdentifier.EMPTY, "mock canCommit failure"))
+                        .doNothing().when(dataTree).validate(any(DataTreeModification.class));
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+
+                if (readWrite) {
+                    shard.tell(prepareForwardedReadyTransaction(shard, transactionID1, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), true), getRef());
+                } else {
+                    shard.tell(prepareBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), true), getRef());
+                }
+
+                expectMsgClass(duration, akka.actor.Status.Failure.class);
+
+                // Send another can commit to ensure the failed one got cleaned
+                // up.
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                if (readWrite) {
+                    shard.tell(prepareForwardedReadyTransaction(shard, transactionID2, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), true), getRef());
+                } else {
+                    shard.tell(prepareBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                            ImmutableNodes.containerNode(TestModel.TEST_QNAME), true), getRef());
+                }
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                expectMsgClass(duration, CommitTransactionReply.class);
+            }
+        };
     }
 
     @Test
-    public void testAbortTransaction() throws Throwable {
-        new ShardTestKit(getSystem()) {{
-            final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
-                    "testAbortTransaction");
+    public void testAbortWithCommitPending() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final Creator<Shard> creator = () -> new Shard(newShardBuilder()) {
+                    @Override
+                    void persistPayload(final TransactionIdentifier transactionId, final Payload payload,
+                            boolean batchHint) {
+                        // Simulate an AbortTransaction message occurring during
+                        // replication, after
+                        // persisting and before finishing the commit to the
+                        // in-memory store.
+
+                        doAbortTransaction(transactionId, null);
+                        super.persistPayload(transactionId, payload, batchHint);
+                    }
+                };
+
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(Props
+                        .create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testAbortWithCommitPending");
 
-            waitUntilLeader(shard);
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                final TransactionIdentifier transactionID = nextTransactionId();
+
+                shard.tell(prepareBatchedModifications(transactionID, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            // Setup 2 simulated transactions with mock cohorts. The first one will be aborted.
+                shard.tell(new CanCommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
 
-            String transactionID1 = "tx1";
-            MutableCompositeModification modification1 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort1 = mock(DOMStoreThreePhaseCommitCohort.class, "cohort1");
-            doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort1).canCommit();
-            doReturn(Futures.immediateFuture(null)).when(cohort1).abort();
+                shard.tell(new CommitTransaction(transactionID, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                final NormalizedNode<?, ?> node = readStore(shard, TestModel.TEST_PATH);
+
+                // Since we're simulating an abort occurring during replication
+                // and before finish commit,
+                // the data should still get written to the in-memory store
+                // since we've gotten past
+                // canCommit and preCommit and persisted the data.
+                assertNotNull(TestModel.TEST_QNAME.getLocalName() + " not found", node);
+            }
+        };
+    }
+
+    @Test
+    public void testTransactionCommitTimeout() throws Exception {
+        dataStoreContextBuilder.shardTransactionCommitTimeoutInSeconds(1);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testTransactionCommitTimeout");
 
-            String transactionID2 = "tx2";
-            MutableCompositeModification modification2 = new MutableCompositeModification();
-            DOMStoreThreePhaseCommitCohort cohort2 = mock(DOMStoreThreePhaseCommitCohort.class, "cohort2");
-            doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort2).canCommit();
+                waitUntilLeader(shard);
 
-            FiniteDuration duration = duration("5 seconds");
-            final Timeout timeout = new Timeout(duration);
+                final FiniteDuration duration = duration("5 seconds");
 
-            // Simulate the ForwardedReadyTransaction messages that would be sent
-            // by the ShardTransaction.
+                writeToStore(shard, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+                writeToStore(shard, TestModel.OUTER_LIST_PATH,
+                        ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build());
 
-            shard.tell(new ForwardedReadyTransaction(transactionID1, CURRENT_VERSION,
-                    cohort1, modification1, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                // Ready 2 Tx's - the first will timeout
 
-            shard.tell(new ForwardedReadyTransaction(transactionID2, CURRENT_VERSION,
-                    cohort2, modification2, true), getRef());
-            expectMsgClass(duration, ReadyTransactionReply.class);
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(
+                        prepareBatchedModifications(transactionID1,
+                                YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                                        .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1).build(),
+                                ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1), false),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            // Send the CanCommitTransaction message for the first Tx.
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                final YangInstanceIdentifier listNodePath = YangInstanceIdentifier.builder(TestModel.OUTER_LIST_PATH)
+                        .nodeWithKey(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2).build();
+                shard.tell(
+                        prepareBatchedModifications(transactionID2, listNodePath,
+                                ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2), false),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
 
-            shard.tell(new CanCommitTransaction(transactionID1).toSerializable(), getRef());
-            CanCommitTransactionReply canCommitReply = CanCommitTransactionReply.fromSerializable(
-                    expectMsgClass(duration, CanCommitTransactionReply.SERIALIZABLE_CLASS));
-            assertEquals("Can commit", true, canCommitReply.getCanCommit());
+                // canCommit 1st Tx. We don't send the commit so it should
+                // timeout.
 
-            // Send the CanCommitTransaction message for the 2nd Tx. This should get queued and
-            // processed after the first Tx completes.
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
 
-            Future<Object> canCommitFuture = Patterns.ask(shard,
-                    new CanCommitTransaction(transactionID2).toSerializable(), timeout);
+                // canCommit the 2nd Tx - it should complete after the 1st Tx
+                // times out.
 
-            // Send the AbortTransaction message for the first Tx. This should trigger the 2nd
-            // Tx to proceed.
+                shard.tell(new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
 
-            shard.tell(new AbortTransaction(transactionID1).toSerializable(), getRef());
-            expectMsgClass(duration, AbortTransactionReply.SERIALIZABLE_CLASS);
+                // Try to commit the 1st Tx - should fail as it's not the
+                // current Tx.
 
-            // Wait for the 2nd Tx to complete the canCommit phase.
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, akka.actor.Status.Failure.class);
 
-            Await.ready(canCommitFuture, duration);
+                // Commit the 2nd Tx.
 
-            InOrder inOrder = inOrder(cohort1, cohort2);
-            inOrder.verify(cohort1).canCommit();
-            inOrder.verify(cohort2).canCommit();
+                shard.tell(new CommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                final NormalizedNode<?, ?> node = readStore(shard, listNodePath);
+                assertNotNull(listNodePath + " not found", node);
+            }
+        };
     }
 
+//    @Test
+//    @Ignore
+//    public void testTransactionCommitQueueCapacityExceeded() throws Throwable {
+//        dataStoreContextBuilder.shardTransactionCommitQueueCapacity(2);
+//
+//        new ShardTestKit(getSystem()) {{
+//            final TestActorRef<Shard> shard = actorFactory.createTestActor(
+//                    newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+//                    "testTransactionCommitQueueCapacityExceeded");
+//
+//            waitUntilLeader(shard);
+//
+//            final FiniteDuration duration = duration("5 seconds");
+//
+//            final ShardDataTree dataStore = shard.underlyingActor().getDataStore();
+//
+//            final TransactionIdentifier transactionID1 = nextTransactionId();
+//            final MutableCompositeModification modification1 = new MutableCompositeModification();
+//            final ShardDataTreeCohort cohort1 = setupMockWriteTransaction("cohort1", dataStore,
+//                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME), transactionID1,
+//                    modification1);
+//
+//            final TransactionIdentifier transactionID2 = nextTransactionId();
+//            final MutableCompositeModification modification2 = new MutableCompositeModification();
+//            final ShardDataTreeCohort cohort2 = setupMockWriteTransaction("cohort2", dataStore,
+//                    TestModel.OUTER_LIST_PATH,
+//                    ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), transactionID2,
+//                    modification2);
+//
+//            final TransactionIdentifier transactionID3 = nextTransactionId();
+//            final MutableCompositeModification modification3 = new MutableCompositeModification();
+//            final ShardDataTreeCohort cohort3 = setupMockWriteTransaction("cohort3", dataStore,
+//                    TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME), transactionID3,
+//                    modification3);
+//
+//            // Ready the Tx's
+//
+//            shard.tell(prepareReadyTransactionMessage(false, shard.underlyingActor(), cohort1, transactionID1,
+//                    modification1), getRef());
+//            expectMsgClass(duration, ReadyTransactionReply.class);
+//
+//            shard.tell(prepareReadyTransactionMessage(false, shard.underlyingActor(), cohort2, transactionID2,
+//                    modification2), getRef());
+//            expectMsgClass(duration, ReadyTransactionReply.class);
+//
+//            // The 3rd Tx should exceed queue capacity and fail.
+//
+//            shard.tell(prepareReadyTransactionMessage(false, shard.underlyingActor(), cohort3, transactionID3,
+//                    modification3), getRef());
+//            expectMsgClass(duration, akka.actor.Status.Failure.class);
+//
+//            // canCommit 1st Tx.
+//
+//            shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+//            expectMsgClass(duration, CanCommitTransactionReply.class);
+//
+//            // canCommit the 2nd Tx - it should get queued.
+//
+//            shard.tell(new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+//
+//            // canCommit the 3rd Tx - should exceed queue capacity and fail.
+//
+//            shard.tell(new CanCommitTransaction(transactionID3, CURRENT_VERSION).toSerializable(), getRef());
+//            expectMsgClass(duration, akka.actor.Status.Failure.class);
+//        }};
+//    }
+
     @Test
-    public void testCreateSnapshot() throws Exception {
-        testCreateSnapshot(true, "testCreateSnapshot");
+    public void testTransactionCommitWithPriorExpiredCohortEntries() throws Exception {
+        dataStoreContextBuilder.shardTransactionCommitTimeoutInSeconds(1);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testTransactionCommitWithPriorExpiredCohortEntries");
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID3 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID3, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // All Tx's are readied. We'll send canCommit for the last one
+                // but not the others. The others
+                // should expire from the queue and the last one should be
+                // processed.
+
+                shard.tell(new CanCommitTransaction(transactionID3, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
+            }
+        };
+    }
+
+    @Test
+    public void testTransactionCommitWithSubsequentExpiredCohortEntry() throws Exception {
+        dataStoreContextBuilder.shardTransactionCommitTimeoutInSeconds(1);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testTransactionCommitWithSubsequentExpiredCohortEntry");
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                final ShardDataTree dataStore = shard.underlyingActor().getDataStore();
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(prepareBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // CanCommit the first Tx so it's the current in-progress Tx.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
+
+                // Ready the second Tx.
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(prepareBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), false), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Ready the third Tx.
+
+                final TransactionIdentifier transactionID3 = nextTransactionId();
+                final DataTreeModification modification3 = dataStore.newModification();
+                new WriteModification(TestModel.TEST2_PATH, ImmutableNodes.containerNode(TestModel.TEST2_QNAME))
+                        .apply(modification3);
+                modification3.ready();
+                final ReadyLocalTransaction readyMessage = new ReadyLocalTransaction(transactionID3, modification3,
+                        true);
+                shard.tell(readyMessage, getRef());
+
+                // Commit the first Tx. After completing, the second should
+                // expire from the queue and the third
+                // Tx committed.
+
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                // Expect commit reply from the third Tx.
+
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                final NormalizedNode<?, ?> node = readStore(shard, TestModel.TEST2_PATH);
+                assertNotNull(TestModel.TEST2_PATH + " not found", node);
+            }
+        };
+    }
+
+    @Test
+    public void testCanCommitBeforeReadyFailure() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        "testCanCommitBeforeReadyFailure");
+
+                shard.tell(new CanCommitTransaction(nextTransactionId(), CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration("5 seconds"), akka.actor.Status.Failure.class);
+            }
+        };
+    }
+
+    @Test
+    public void testAbortAfterCanCommit() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()), "testAbortAfterCanCommit");
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+                final Timeout timeout = new Timeout(duration);
+
+                // Ready 2 transactions - the first one will be aborted.
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Send the CanCommitTransaction message for the first Tx.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                CanCommitTransactionReply canCommitReply = CanCommitTransactionReply
+                        .fromSerializable(expectMsgClass(duration, CanCommitTransactionReply.class));
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
+
+                // Send the CanCommitTransaction message for the 2nd Tx. This
+                // should get queued and
+                // processed after the first Tx completes.
+
+                final Future<Object> canCommitFuture = Patterns.ask(shard,
+                        new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), timeout);
+
+                // Send the AbortTransaction message for the first Tx. This
+                // should trigger the 2nd
+                // Tx to proceed.
+
+                shard.tell(new AbortTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, AbortTransactionReply.class);
+
+                // Wait for the 2nd Tx to complete the canCommit phase.
+
+                canCommitReply = (CanCommitTransactionReply) Await.result(canCommitFuture, duration);
+                assertEquals("Can commit", true, canCommitReply.getCanCommit());
+            }
+        };
+    }
+
+    @Test
+    public void testAbortAfterReady() throws Exception {
+        dataStoreContextBuilder.shardTransactionCommitTimeoutInSeconds(1);
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()), "testAbortAfterReady");
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                // Ready a tx.
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Send the AbortTransaction message.
+
+                shard.tell(new AbortTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, AbortTransactionReply.class);
+
+                assertEquals("getPendingTxCommitQueueSize", 0, shard.underlyingActor().getPendingTxCommitQueueSize());
+
+                // Now send CanCommitTransaction - should fail.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                final Throwable failure = expectMsgClass(duration, akka.actor.Status.Failure.class).cause();
+                assertTrue("Failure type", failure instanceof IllegalStateException);
+
+                // Ready and CanCommit another and verify success.
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                shard.tell(new CanCommitTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
+            }
+        };
+    }
+
+    @Test
+    public void testAbortQueuedTransaction() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()), "testAbortAfterReady");
+
+                waitUntilLeader(shard);
+
+                final FiniteDuration duration = duration("5 seconds");
+
+                // Ready 3 tx's.
+
+                final TransactionIdentifier transactionID1 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID1, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID2 = nextTransactionId();
+                shard.tell(newBatchedModifications(transactionID2, TestModel.TEST_PATH,
+                        ImmutableNodes.containerNode(TestModel.TEST_QNAME), true, false, 1), getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                final TransactionIdentifier transactionID3 = nextTransactionId();
+                shard.tell(
+                        newBatchedModifications(transactionID3, TestModel.OUTER_LIST_PATH,
+                                ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).build(), true, false, 1),
+                        getRef());
+                expectMsgClass(duration, ReadyTransactionReply.class);
+
+                // Abort the second tx while it's queued.
+
+                shard.tell(new AbortTransaction(transactionID2, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, AbortTransactionReply.class);
+
+                // Commit the other 2.
+
+                shard.tell(new CanCommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
+
+                shard.tell(new CommitTransaction(transactionID1, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                shard.tell(new CanCommitTransaction(transactionID3, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CanCommitTransactionReply.class);
+
+                shard.tell(new CommitTransaction(transactionID3, CURRENT_VERSION).toSerializable(), getRef());
+                expectMsgClass(duration, CommitTransactionReply.class);
+
+                assertEquals("getPendingTxCommitQueueSize", 0, shard.underlyingActor().getPendingTxCommitQueueSize());
+            }
+        };
     }
 
     @Test
@@ -1408,244 +1892,407 @@ public class ShardTest extends AbstractShardTest {
         testCreateSnapshot(false, "testCreateSnapshotWithNonPersistentData");
     }
 
-    @SuppressWarnings("serial")
-    public void testCreateSnapshot(final boolean persistent, final String shardActorName) throws Exception{
+    @Test
+    public void testCreateSnapshot() throws Exception {
+        testCreateSnapshot(true, "testCreateSnapshot");
+    }
 
+    private void testCreateSnapshot(final boolean persistent, final String shardActorName) throws Exception {
         final AtomicReference<CountDownLatch> latch = new AtomicReference<>(new CountDownLatch(1));
 
         final AtomicReference<Object> savedSnapshot = new AtomicReference<>();
         class TestPersistentDataProvider extends DelegatingPersistentDataProvider {
-            TestPersistentDataProvider(DataPersistenceProvider delegate) {
+            TestPersistentDataProvider(final DataPersistenceProvider delegate) {
                 super(delegate);
             }
 
             @Override
-            public void saveSnapshot(Object o) {
-                savedSnapshot.set(o);
-                super.saveSnapshot(o);
+            public void saveSnapshot(final Object obj) {
+                savedSnapshot.set(obj);
+                super.saveSnapshot(obj);
             }
         }
 
         dataStoreContextBuilder.persistent(persistent);
 
-        new ShardTestKit(getSystem()) {{
-            class TestShard extends Shard {
+        class TestShard extends Shard {
 
-                protected TestShard(ShardIdentifier name, Map<String, String> peerAddresses,
-                                    DatastoreContext datastoreContext, SchemaContext schemaContext) {
-                    super(name, peerAddresses, datastoreContext, schemaContext);
-                    setPersistence(new TestPersistentDataProvider(super.persistence()));
-                }
-
-                @Override
-                public void handleCommand(Object message) {
-                    super.handleCommand(message);
+            protected TestShard(final AbstractBuilder<?, ?> builder) {
+                super(builder);
+                setPersistence(new TestPersistentDataProvider(super.persistence()));
+            }
 
-                    if (message instanceof SaveSnapshotSuccess || message.equals("commit_snapshot")) {
-                        latch.get().countDown();
-                    }
-                }
+            @Override
+            public void handleCommand(final Object message) {
+                super.handleCommand(message);
 
-                @Override
-                public RaftActorContext getRaftActorContext() {
-                    return super.getRaftActorContext();
+                // XXX:  commit_snapshot equality check references RaftActorSnapshotMessageSupport.COMMIT_SNAPSHOT
+                if (message instanceof SaveSnapshotSuccess || "commit_snapshot".equals(message.toString())) {
+                    latch.get().countDown();
                 }
             }
 
-            Creator<Shard> creator = new Creator<Shard>() {
-                @Override
-                public Shard create() throws Exception {
-                    return new TestShard(shardID, Collections.<String,String>emptyMap(),
-                            newDatastoreContext(), SCHEMA_CONTEXT);
-                }
-            };
-
-            TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
-                    Props.create(new DelegatingShardCreator(creator)), shardActorName);
-
-            waitUntilLeader(shard);
-
-            writeToStore(shard, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
-
-            NormalizedNode<?,?> expectedRoot = readStore(shard, YangInstanceIdentifier.builder().build());
-
-            // Trigger creation of a snapshot by ensuring
-            RaftActorContext raftActorContext = ((TestShard) shard.underlyingActor()).getRaftActorContext();
-            raftActorContext.getSnapshotManager().capture(mock(ReplicatedLogEntry.class), -1);
-
-            assertEquals("Snapshot saved", true, latch.get().await(5, TimeUnit.SECONDS));
+            @Override
+            public RaftActorContext getRaftActorContext() {
+                return super.getRaftActorContext();
+            }
+        }
 
-            assertTrue("Invalid saved snapshot " + savedSnapshot.get(),
-                    savedSnapshot.get() instanceof Snapshot);
+        new ShardTestKit(getSystem()) {
+            {
+                final Creator<Shard> creator = () -> new TestShard(newShardBuilder());
 
-            verifySnapshot((Snapshot)savedSnapshot.get(), expectedRoot);
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(Props
+                        .create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        shardActorName);
 
-            latch.set(new CountDownLatch(1));
-            savedSnapshot.set(null);
+                waitUntilLeader(shard);
+                writeToStore(shard, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
 
-            raftActorContext.getSnapshotManager().capture(mock(ReplicatedLogEntry.class), -1);
+                final NormalizedNode<?, ?> expectedRoot = readStore(shard, YangInstanceIdentifier.EMPTY);
 
-            assertEquals("Snapshot saved", true, latch.get().await(5, TimeUnit.SECONDS));
+                // Trigger creation of a snapshot by ensuring
+                final RaftActorContext raftActorContext = ((TestShard) shard.underlyingActor()).getRaftActorContext();
+                raftActorContext.getSnapshotManager().capture(mock(ReplicatedLogEntry.class), -1);
+                awaitAndValidateSnapshot(expectedRoot);
 
-            assertTrue("Invalid saved snapshot " + savedSnapshot.get(),
-                    savedSnapshot.get() instanceof Snapshot);
+                raftActorContext.getSnapshotManager().capture(mock(ReplicatedLogEntry.class), -1);
+                awaitAndValidateSnapshot(expectedRoot);
+            }
 
-            verifySnapshot((Snapshot)savedSnapshot.get(), expectedRoot);
+            private void awaitAndValidateSnapshot(final NormalizedNode<?, ?> expectedRoot)
+                    throws InterruptedException, IOException {
+                assertEquals("Snapshot saved", true, latch.get().await(5, TimeUnit.SECONDS));
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }
+                assertTrue("Invalid saved snapshot " + savedSnapshot.get(), savedSnapshot.get() instanceof Snapshot);
 
-        private void verifySnapshot(Snapshot snapshot, NormalizedNode<?,?> expectedRoot) {
+                verifySnapshot((Snapshot) savedSnapshot.get(), expectedRoot);
 
-            NormalizedNode<?, ?> actual = SerializationUtils.deserializeNormalizedNode(snapshot.getState());
-            assertEquals("Root node", expectedRoot, actual);
+                latch.set(new CountDownLatch(1));
+                savedSnapshot.set(null);
+            }
 
-        }};
+            private void verifySnapshot(final Snapshot snapshot, final NormalizedNode<?, ?> expectedRoot)
+                    throws IOException {
+                final NormalizedNode<?, ?> actual = ((ShardSnapshotState)snapshot.getState()).getSnapshot()
+                        .getRootNode().get();
+                assertEquals("Root node", expectedRoot, actual);
+            }
+        };
     }
 
     /**
-     * This test simply verifies that the applySnapShot logic will work
-     * @throws ReadFailedException
+     * This test simply verifies that the applySnapShot logic will work.
      */
     @Test
-    public void testInMemoryDataStoreRestore() throws ReadFailedException {
-        InMemoryDOMDataStore store = new InMemoryDOMDataStore("test", MoreExecutors.sameThreadExecutor());
+    public void testInMemoryDataTreeRestore() throws ReadFailedException, DataValidationFailedException {
+        final DataTree store = InMemoryDataTreeFactory.getInstance().create(TreeType.OPERATIONAL);
+        store.setSchemaContext(SCHEMA_CONTEXT);
 
-        store.onGlobalContextUpdated(SCHEMA_CONTEXT);
-
-        DOMStoreWriteTransaction putTransaction = store.newWriteOnlyTransaction();
+        final DataTreeModification putTransaction = store.takeSnapshot().newModification();
         putTransaction.write(TestModel.TEST_PATH,
             ImmutableNodes.containerNode(TestModel.TEST_QNAME));
-        commitTransaction(putTransaction);
+        commitTransaction(store, putTransaction);
 
 
-        NormalizedNode<?, ?> expected = readStore(store);
+        final NormalizedNode<?, ?> expected = readStore(store, YangInstanceIdentifier.EMPTY);
 
-        DOMStoreWriteTransaction writeTransaction = store.newWriteOnlyTransaction();
+        final DataTreeModification writeTransaction = store.takeSnapshot().newModification();
 
-        writeTransaction.delete(YangInstanceIdentifier.builder().build());
-        writeTransaction.write(YangInstanceIdentifier.builder().build(), expected);
+        writeTransaction.delete(YangInstanceIdentifier.EMPTY);
+        writeTransaction.write(YangInstanceIdentifier.EMPTY, expected);
 
-        commitTransaction(writeTransaction);
+        commitTransaction(store, writeTransaction);
 
-        NormalizedNode<?, ?> actual = readStore(store);
+        final NormalizedNode<?, ?> actual = readStore(store, YangInstanceIdentifier.EMPTY);
 
         assertEquals(expected, actual);
     }
 
     @Test
-    public void testRecoveryApplicable(){
-
-        final DatastoreContext persistentContext = DatastoreContext.newBuilder().
-                shardJournalRecoveryLogBatchSize(3).shardSnapshotBatchCount(5000).persistent(true).build();
+    public void testRecoveryApplicable() {
 
-        final Props persistentProps = Shard.props(shardID, Collections.<String, String>emptyMap(),
-                persistentContext, SCHEMA_CONTEXT);
+        final DatastoreContext persistentContext = DatastoreContext.newBuilder()
+                .shardJournalRecoveryLogBatchSize(3).shardSnapshotBatchCount(5000).persistent(true).build();
 
-        final DatastoreContext nonPersistentContext = DatastoreContext.newBuilder().
-                shardJournalRecoveryLogBatchSize(3).shardSnapshotBatchCount(5000).persistent(false).build();
+        final Props persistentProps = Shard.builder().id(shardID).datastoreContext(persistentContext)
+                .schemaContext(SCHEMA_CONTEXT).props();
 
-        final Props nonPersistentProps = Shard.props(shardID, Collections.<String, String>emptyMap(),
-                nonPersistentContext, SCHEMA_CONTEXT);
+        final DatastoreContext nonPersistentContext = DatastoreContext.newBuilder()
+                .shardJournalRecoveryLogBatchSize(3).shardSnapshotBatchCount(5000).persistent(false).build();
 
-        new ShardTestKit(getSystem()) {{
-            TestActorRef<Shard> shard1 = TestActorRef.create(getSystem(),
-                    persistentProps, "testPersistence1");
+        final Props nonPersistentProps = Shard.builder().id(shardID).datastoreContext(nonPersistentContext)
+                .schemaContext(SCHEMA_CONTEXT).props();
 
-            assertTrue("Recovery Applicable", shard1.underlyingActor().persistence().isRecoveryApplicable());
-
-            shard1.tell(PoisonPill.getInstance(), ActorRef.noSender());
-
-            TestActorRef<Shard> shard2 = TestActorRef.create(getSystem(),
-                    nonPersistentProps, "testPersistence2");
-
-            assertFalse("Recovery Not Applicable", shard2.underlyingActor().persistence().isRecoveryApplicable());
+        new ShardTestKit(getSystem()) {
+            {
+                final TestActorRef<Shard> shard1 = actorFactory.createTestActor(persistentProps, "testPersistence1");
 
-            shard2.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                assertTrue("Recovery Applicable", shard1.underlyingActor().persistence().isRecoveryApplicable());
 
-        }};
+                final TestActorRef<Shard> shard2 = actorFactory.createTestActor(nonPersistentProps, "testPersistence2");
 
+                assertFalse("Recovery Not Applicable", shard2.underlyingActor().persistence().isRecoveryApplicable());
+            }
+        };
     }
 
     @Test
     public void testOnDatastoreContext() {
-        new ShardTestKit(getSystem()) {{
-            dataStoreContextBuilder.persistent(true);
-
-            TestActorRef<Shard> shard = TestActorRef.create(getSystem(), newShardProps(), "testOnDatastoreContext");
+        new ShardTestKit(getSystem()) {
+            {
+                dataStoreContextBuilder.persistent(true);
 
-            assertEquals("isRecoveryApplicable", true,
-                    shard.underlyingActor().persistence().isRecoveryApplicable());
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(newShardProps(),
+                        "testOnDatastoreContext");
 
-            waitUntilLeader(shard);
+                assertEquals("isRecoveryApplicable", true,
+                        shard.underlyingActor().persistence().isRecoveryApplicable());
 
-            shard.tell(dataStoreContextBuilder.persistent(false).build(), ActorRef.noSender());
+                waitUntilLeader(shard);
 
-            assertEquals("isRecoveryApplicable", false,
-                    shard.underlyingActor().persistence().isRecoveryApplicable());
+                shard.tell(dataStoreContextBuilder.persistent(false).build(), ActorRef.noSender());
 
-            shard.tell(dataStoreContextBuilder.persistent(true).build(), ActorRef.noSender());
+                assertEquals("isRecoveryApplicable", false,
+                        shard.underlyingActor().persistence().isRecoveryApplicable());
 
-            assertEquals("isRecoveryApplicable", true,
-                    shard.underlyingActor().persistence().isRecoveryApplicable());
+                shard.tell(dataStoreContextBuilder.persistent(true).build(), ActorRef.noSender());
 
-            shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
-        }};
+                assertEquals("isRecoveryApplicable", true,
+                        shard.underlyingActor().persistence().isRecoveryApplicable());
+            }
+        };
     }
 
     @Test
     public void testRegisterRoleChangeListener() throws Exception {
         new ShardTestKit(getSystem()) {
             {
-                final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
                         newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
                         "testRegisterRoleChangeListener");
 
                 waitUntilLeader(shard);
 
-                TestActorRef<MessageCollectorActor> listener =
+                final TestActorRef<MessageCollectorActor> listener =
                         TestActorRef.create(getSystem(), Props.create(MessageCollectorActor.class));
 
                 shard.tell(new RegisterRoleChangeListener(), listener);
 
-                // TODO: MessageCollectorActor exists as a test util in both the akka-raft and distributed-datastore
-                // projects. Need to move it to commons as a regular utility and then we can get rid of this arbitrary
-                // sleep.
-                Uninterruptibles.sleepUninterruptibly(100, TimeUnit.MILLISECONDS);
+                MessageCollectorActor.expectFirstMatching(listener, RegisterRoleChangeListenerReply.class);
+
+                ShardLeaderStateChanged leaderStateChanged = MessageCollectorActor.expectFirstMatching(listener,
+                    ShardLeaderStateChanged.class);
+                assertEquals("getLocalShardDataTree present", true,
+                        leaderStateChanged.getLocalShardDataTree().isPresent());
+                assertSame("getLocalShardDataTree", shard.underlyingActor().getDataStore().getDataTree(),
+                    leaderStateChanged.getLocalShardDataTree().get());
+
+                MessageCollectorActor.clearMessages(listener);
+
+                // Force a leader change
 
-                List<Object> allMatching = MessageCollectorActor.getAllMatching(listener, RegisterRoleChangeListenerReply.class);
+                shard.tell(new RequestVote(10000, "member2", 50, 50), getRef());
 
-                assertEquals(1, allMatching.size());
+                leaderStateChanged = MessageCollectorActor.expectFirstMatching(listener,
+                        ShardLeaderStateChanged.class);
+                assertEquals("getLocalShardDataTree present", false,
+                        leaderStateChanged.getLocalShardDataTree().isPresent());
             }
         };
     }
 
     @Test
     public void testFollowerInitialSyncStatus() throws Exception {
-        final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
+        final TestActorRef<Shard> shard = actorFactory.createTestActor(
                 newShardProps().withDispatcher(Dispatchers.DefaultDispatcherId()),
                 "testFollowerInitialSyncStatus");
 
-        shard.underlyingActor().onReceiveCommand(new FollowerInitialSyncUpStatus(false, "member-1-shard-inventory-operational"));
+        shard.underlyingActor().handleNonRaftCommand(new FollowerInitialSyncUpStatus(false,
+                "member-1-shard-inventory-operational"));
 
         assertEquals(false, shard.underlyingActor().getShardMBean().getFollowerInitialSyncStatus());
 
-        shard.underlyingActor().onReceiveCommand(new FollowerInitialSyncUpStatus(true, "member-1-shard-inventory-operational"));
+        shard.underlyingActor().handleNonRaftCommand(new FollowerInitialSyncUpStatus(true,
+                "member-1-shard-inventory-operational"));
 
         assertEquals(true, shard.underlyingActor().getShardMBean().getFollowerInitialSyncStatus());
+    }
+
+    @Test
+    public void testClusteredDataChangeListenerDelayedRegistration() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final String testName = "testClusteredDataChangeListenerDelayedRegistration";
+                dataStoreContextBuilder.shardElectionTimeoutFactor(1000)
+                        .customRaftPolicyImplementation(DisableElectionsRaftPolicy.class.getName());
 
-        shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                final MockDataChangeListener listener = new MockDataChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataChangeListener.props(listener, path),
+                        actorFactory.generateActorId(testName + "-DataChangeListener"));
+
+                setupInMemorySnapshotStore();
+
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        actorFactory.generateActorId(testName + "-shard"));
+
+                waitUntilNoLeader(shard);
+
+                shard.tell(new RegisterChangeListener(path, dclActor, AsyncDataBroker.DataChangeScope.BASE, true),
+                        getRef());
+                final RegisterChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterChangeListenerReply.class);
+                assertNotNull("getListenerRegistrationPath", reply.getListenerRegistrationPath());
+
+                shard.tell(DatastoreContext.newBuilderFrom(dataStoreContextBuilder.build())
+                        .customRaftPolicyImplementation(null).build(), ActorRef.noSender());
+
+                listener.waitForChangeEvents();
+            }
+        };
     }
 
-    private void commitTransaction(final DOMStoreWriteTransaction transaction) {
-        DOMStoreThreePhaseCommitCohort commitCohort = transaction.ready();
-        ListenableFuture<Void> future =
-            commitCohort.preCommit();
-        try {
-            future.get();
-            future = commitCohort.commit();
-            future.get();
-        } catch (InterruptedException | ExecutionException e) {
-        }
+    @Test
+    public void testClusteredDataChangeListenerRegistration() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final String testName = "testClusteredDataChangeListenerRegistration";
+                final ShardIdentifier followerShardID = ShardIdentifier.create("inventory",
+                        MemberName.forName(actorFactory.generateActorId(testName + "-follower")), "config");
+
+                final ShardIdentifier leaderShardID = ShardIdentifier.create("inventory",
+                        MemberName.forName(actorFactory.generateActorId(testName + "-leader")), "config");
+
+                final TestActorRef<Shard> followerShard = actorFactory
+                        .createTestActor(Shard.builder().id(followerShardID)
+                                .datastoreContext(dataStoreContextBuilder.shardElectionTimeoutFactor(1000).build())
+                                .peerAddresses(Collections.singletonMap(leaderShardID.toString(),
+                                        "akka://test/user/" + leaderShardID.toString()))
+                                .schemaContext(SCHEMA_CONTEXT).props()
+                                .withDispatcher(Dispatchers.DefaultDispatcherId()), followerShardID.toString());
+
+                final TestActorRef<Shard> leaderShard = actorFactory
+                        .createTestActor(Shard.builder().id(leaderShardID).datastoreContext(newDatastoreContext())
+                                .peerAddresses(Collections.singletonMap(followerShardID.toString(),
+                                        "akka://test/user/" + followerShardID.toString()))
+                                .schemaContext(SCHEMA_CONTEXT).props()
+                                .withDispatcher(Dispatchers.DefaultDispatcherId()), leaderShardID.toString());
+
+                leaderShard.tell(TimeoutNow.INSTANCE, ActorRef.noSender());
+                final String leaderPath = waitUntilLeader(followerShard);
+                assertEquals("Shard leader path", leaderShard.path().toString(), leaderPath);
+
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                final MockDataChangeListener listener = new MockDataChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataChangeListener.props(listener, path),
+                        actorFactory.generateActorId(testName + "-DataChangeListener"));
+
+                followerShard.tell(
+                        new RegisterChangeListener(path, dclActor, AsyncDataBroker.DataChangeScope.BASE, true),
+                        getRef());
+                final RegisterChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterChangeListenerReply.class);
+                assertNotNull("getListenerRegistratioznPath", reply.getListenerRegistrationPath());
+
+                writeToStore(followerShard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+
+                listener.waitForChangeEvents();
+            }
+        };
+    }
+
+    @Test
+    public void testClusteredDataTreeChangeListenerDelayedRegistration() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final String testName = "testClusteredDataTreeChangeListenerDelayedRegistration";
+                dataStoreContextBuilder.shardElectionTimeoutFactor(1000)
+                        .customRaftPolicyImplementation(DisableElectionsRaftPolicy.class.getName());
+
+                final MockDataTreeChangeListener listener = new MockDataTreeChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataTreeChangeListenerActor.props(listener,
+                        TestModel.TEST_PATH), actorFactory.generateActorId(testName + "-DataTreeChangeListener"));
+
+                setupInMemorySnapshotStore();
+
+                final TestActorRef<Shard> shard = actorFactory.createTestActor(
+                        newShardBuilder().props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                        actorFactory.generateActorId(testName + "-shard"));
+
+                waitUntilNoLeader(shard);
+
+                shard.tell(new RegisterDataTreeChangeListener(TestModel.TEST_PATH, dclActor, true), getRef());
+                final RegisterDataTreeChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterDataTreeChangeListenerReply.class);
+                assertNotNull("getListenerRegistrationPath", reply.getListenerRegistrationPath());
+
+                shard.tell(DatastoreContext.newBuilderFrom(dataStoreContextBuilder.build())
+                        .customRaftPolicyImplementation(null).build(), ActorRef.noSender());
+
+                listener.waitForChangeEvents();
+            }
+        };
+    }
+
+    @Test
+    public void testClusteredDataTreeChangeListenerRegistration() throws Exception {
+        new ShardTestKit(getSystem()) {
+            {
+                final String testName = "testClusteredDataTreeChangeListenerRegistration";
+                final ShardIdentifier followerShardID = ShardIdentifier.create("inventory",
+                        MemberName.forName(actorFactory.generateActorId(testName + "-follower")), "config");
+
+                final ShardIdentifier leaderShardID = ShardIdentifier.create("inventory",
+                        MemberName.forName(actorFactory.generateActorId(testName + "-leader")), "config");
+
+                final TestActorRef<Shard> followerShard = actorFactory
+                        .createTestActor(Shard.builder().id(followerShardID)
+                                .datastoreContext(dataStoreContextBuilder.shardElectionTimeoutFactor(1000).build())
+                                .peerAddresses(Collections.singletonMap(leaderShardID.toString(),
+                                        "akka://test/user/" + leaderShardID.toString()))
+                                .schemaContext(SCHEMA_CONTEXT).props()
+                                .withDispatcher(Dispatchers.DefaultDispatcherId()), followerShardID.toString());
+
+                final TestActorRef<Shard> leaderShard = actorFactory
+                        .createTestActor(Shard.builder().id(leaderShardID).datastoreContext(newDatastoreContext())
+                                .peerAddresses(Collections.singletonMap(followerShardID.toString(),
+                                        "akka://test/user/" + followerShardID.toString()))
+                                .schemaContext(SCHEMA_CONTEXT).props()
+                                .withDispatcher(Dispatchers.DefaultDispatcherId()), leaderShardID.toString());
+
+                leaderShard.tell(TimeoutNow.INSTANCE, ActorRef.noSender());
+                final String leaderPath = waitUntilLeader(followerShard);
+                assertEquals("Shard leader path", leaderShard.path().toString(), leaderPath);
+
+                final YangInstanceIdentifier path = TestModel.TEST_PATH;
+                final MockDataTreeChangeListener listener = new MockDataTreeChangeListener(1);
+                final ActorRef dclActor = actorFactory.createActor(DataTreeChangeListenerActor.props(listener, path),
+                        actorFactory.generateActorId(testName + "-DataTreeChangeListener"));
+
+                followerShard.tell(new RegisterDataTreeChangeListener(TestModel.TEST_PATH, dclActor, true), getRef());
+                final RegisterDataTreeChangeListenerReply reply = expectMsgClass(duration("5 seconds"),
+                        RegisterDataTreeChangeListenerReply.class);
+                assertNotNull("getListenerRegistrationPath", reply.getListenerRegistrationPath());
+
+                writeToStore(followerShard, path, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
+
+                listener.waitForChangeEvents();
+            }
+        };
+    }
+
+    @Test
+    public void testServerRemoved() throws Exception {
+        final TestActorRef<MessageCollectorActor> parent = actorFactory.createTestActor(MessageCollectorActor.props());
+
+        final ActorRef shard = parent.underlyingActor().context().actorOf(
+                newShardBuilder().props().withDispatcher(Dispatchers.DefaultDispatcherId()),
+                "testServerRemoved");
+
+        shard.tell(new ServerRemoved("test"), ActorRef.noSender());
+
+        MessageCollectorActor.expectFirstMatching(parent, ServerRemoved.class);
     }
 }