Bug 2260: Reduce overhead of unused TransactionProxy instances
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / test / java / org / opendaylight / controller / cluster / datastore / TransactionProxyTest.java
index 62052f38ab89b6962dc31622332f85113492c924..abfe7eae22a15b69fd4dc1c71df46befe5059e31 100644 (file)
 package org.opendaylight.controller.cluster.datastore;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Matchers.argThat;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Matchers.isA;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.opendaylight.controller.cluster.datastore.TransactionProxy.TransactionType.READ_ONLY;
+import static org.opendaylight.controller.cluster.datastore.TransactionProxy.TransactionType.READ_WRITE;
+import static org.opendaylight.controller.cluster.datastore.TransactionProxy.TransactionType.WRITE_ONLY;
 import akka.actor.ActorRef;
+import akka.actor.ActorSelection;
+import akka.actor.ActorSystem;
 import akka.actor.Props;
+import akka.dispatch.Futures;
+import akka.testkit.JavaTestKit;
 import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.CheckedFuture;
-import com.google.common.util.concurrent.ListenableFuture;
-import com.google.common.util.concurrent.ListeningExecutorService;
-import com.google.common.util.concurrent.MoreExecutors;
-import junit.framework.Assert;
-import org.junit.After;
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Uninterruptibles;
+import com.typesafe.config.Config;
+import com.typesafe.config.ConfigFactory;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import org.junit.AfterClass;
+import org.junit.Assert;
 import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.ArgumentMatcher;
+import org.mockito.InOrder;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.controller.cluster.datastore.DatastoreContext.Builder;
+import org.opendaylight.controller.cluster.datastore.TransactionProxy.TransactionType;
 import org.opendaylight.controller.cluster.datastore.exceptions.PrimaryNotFoundException;
 import org.opendaylight.controller.cluster.datastore.exceptions.TimeoutException;
+import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
+import org.opendaylight.controller.cluster.datastore.messages.BatchedModificationsReply;
 import org.opendaylight.controller.cluster.datastore.messages.CloseTransaction;
+import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
+import org.opendaylight.controller.cluster.datastore.messages.DataExists;
 import org.opendaylight.controller.cluster.datastore.messages.DataExistsReply;
 import org.opendaylight.controller.cluster.datastore.messages.DeleteData;
+import org.opendaylight.controller.cluster.datastore.messages.DeleteDataReply;
 import org.opendaylight.controller.cluster.datastore.messages.MergeData;
-import org.opendaylight.controller.cluster.datastore.messages.PrimaryFound;
+import org.opendaylight.controller.cluster.datastore.messages.MergeDataReply;
+import org.opendaylight.controller.cluster.datastore.messages.ReadData;
 import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
+import org.opendaylight.controller.cluster.datastore.messages.ReadyTransaction;
 import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
 import org.opendaylight.controller.cluster.datastore.messages.WriteData;
+import org.opendaylight.controller.cluster.datastore.messages.WriteDataReply;
+import org.opendaylight.controller.cluster.datastore.modification.AbstractModification;
+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.WriteModification;
+import org.opendaylight.controller.cluster.datastore.shardstrategy.DefaultShardStrategy;
 import org.opendaylight.controller.cluster.datastore.shardstrategy.ShardStrategyFactory;
 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
 import org.opendaylight.controller.cluster.datastore.utils.DoNothingActor;
-import org.opendaylight.controller.cluster.datastore.utils.MessageCollectorActor;
-import org.opendaylight.controller.cluster.datastore.utils.MockActorContext;
-import org.opendaylight.controller.cluster.datastore.utils.MockClusterWrapper;
 import org.opendaylight.controller.cluster.datastore.utils.MockConfiguration;
+import org.opendaylight.controller.md.cluster.datastore.model.CarsModel;
 import org.opendaylight.controller.md.cluster.datastore.model.TestModel;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
+import org.opendaylight.controller.protobuff.messages.transaction.ShardTransactionMessages;
 import org.opendaylight.controller.protobuff.messages.transaction.ShardTransactionMessages.CreateTransactionReply;
 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
-import scala.concurrent.duration.FiniteDuration;
+import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+import scala.concurrent.Await;
+import scala.concurrent.Future;
+import scala.concurrent.Promise;
+import scala.concurrent.duration.Duration;
 
-import java.util.List;
-import java.util.concurrent.Executors;
+@SuppressWarnings("resource")
+public class TransactionProxyTest {
 
-import static junit.framework.Assert.fail;
-import static org.mockito.Matchers.any;
-import static org.mockito.Matchers.anyString;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
+    @SuppressWarnings("serial")
+    static class TestException extends RuntimeException {
+    }
+
+    static interface Invoker {
+        CheckedFuture<?, ReadFailedException> invoke(TransactionProxy proxy) throws Exception;
+    }
 
-public class TransactionProxyTest extends AbstractActorTest {
+    private static ActorSystem system;
 
     private final Configuration configuration = new MockConfiguration();
 
-    private final ActorContext testContext =
-        new ActorContext(getSystem(), getSystem().actorOf(Props.create(DoNothingActor.class)), new MockClusterWrapper(), configuration );
+    @Mock
+    private ActorContext mockActorContext;
+
+    private SchemaContext schemaContext;
+
+    @Mock
+    private ClusterWrapper mockClusterWrapper;
+
+    private final String memberName = "mock-member";
+
+    private final Builder dataStoreContextBuilder = DatastoreContext.newBuilder().operationTimeoutInSeconds(2).
+            shardBatchedModificationCount(1);
+
+    @BeforeClass
+    public static void setUpClass() throws IOException {
 
-    private final ListeningExecutorService transactionExecutor =
-        MoreExecutors.listeningDecorator(Executors.newSingleThreadExecutor());
+        Config config = ConfigFactory.parseMap(ImmutableMap.<String, Object>builder().
+                put("akka.actor.default-dispatcher.type",
+                        "akka.testkit.CallingThreadDispatcherConfigurator").build()).
+                withFallback(ConfigFactory.load());
+        system = ActorSystem.create("test", config);
+    }
+
+    @AfterClass
+    public static void tearDownClass() throws IOException {
+        JavaTestKit.shutdownActorSystem(system);
+        system = null;
+    }
 
     @Before
     public void setUp(){
+        MockitoAnnotations.initMocks(this);
+
+        schemaContext = TestModel.createTestContext();
+
+        doReturn(getSystem()).when(mockActorContext).getActorSystem();
+        doReturn(getSystem().dispatchers().defaultGlobalDispatcher()).when(mockActorContext).getClientDispatcher();
+        doReturn(memberName).when(mockActorContext).getCurrentMemberName();
+        doReturn(schemaContext).when(mockActorContext).getSchemaContext();
+        doReturn(mockClusterWrapper).when(mockActorContext).getClusterWrapper();
+        doReturn(mockClusterWrapper).when(mockActorContext).getClusterWrapper();
+        doReturn(dataStoreContextBuilder.build()).when(mockActorContext).getDatastoreContext();
+        doReturn(10).when(mockActorContext).getTransactionOutstandingOperationLimit();
+
         ShardStrategyFactory.setConfiguration(configuration);
     }
 
-    @After
-    public void tearDown() {
-        transactionExecutor.shutdownNow();
+    private ActorSystem getSystem() {
+        return system;
     }
 
-    @Test
-    public void testRead() throws Exception {
-        final Props props = Props.create(DoNothingActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+    private CreateTransaction eqCreateTransaction(final String memberName,
+            final TransactionType type) {
+        ArgumentMatcher<CreateTransaction> matcher = new ArgumentMatcher<CreateTransaction>() {
+            @Override
+            public boolean matches(Object argument) {
+                if(CreateTransaction.SERIALIZABLE_CLASS.equals(argument.getClass())) {
+                    CreateTransaction obj = CreateTransaction.fromSerializable(argument);
+                    return obj.getTransactionId().startsWith(memberName) &&
+                            obj.getTransactionType() == type.ordinal();
+                }
+
+                return false;
+            }
+        };
+
+        return argThat(matcher);
+    }
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+    private DataExists eqSerializedDataExists() {
+        ArgumentMatcher<DataExists> matcher = new ArgumentMatcher<DataExists>() {
+            @Override
+            public boolean matches(Object argument) {
+                return DataExists.SERIALIZABLE_CLASS.equals(argument.getClass()) &&
+                       DataExists.fromSerializable(argument).getPath().equals(TestModel.TEST_PATH);
+            }
+        };
 
+        return argThat(matcher);
+    }
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+    private DataExists eqDataExists() {
+        ArgumentMatcher<DataExists> matcher = new ArgumentMatcher<DataExists>() {
+            @Override
+            public boolean matches(Object argument) {
+                return (argument instanceof DataExists) &&
+                    ((DataExists)argument).getPath().equals(TestModel.TEST_PATH);
+            }
+        };
 
+        return argThat(matcher);
+    }
 
-        actorContext.setExecuteRemoteOperationResponse(
-            new ReadDataReply(TestModel.createTestContext(), null)
-                .toSerializable());
+    private ReadData eqSerializedReadData() {
+        return eqSerializedReadData(TestModel.TEST_PATH);
+    }
 
-        ListenableFuture<Optional<NormalizedNode<?, ?>>> read =
-            transactionProxy.read(TestModel.TEST_PATH);
+    private ReadData eqSerializedReadData(final YangInstanceIdentifier path) {
+        ArgumentMatcher<ReadData> matcher = new ArgumentMatcher<ReadData>() {
+            @Override
+            public boolean matches(Object argument) {
+                return ReadData.SERIALIZABLE_CLASS.equals(argument.getClass()) &&
+                       ReadData.fromSerializable(argument).getPath().equals(path);
+            }
+        };
 
-        Optional<NormalizedNode<?, ?>> normalizedNodeOptional = read.get();
+        return argThat(matcher);
+    }
 
-        Assert.assertFalse(normalizedNodeOptional.isPresent());
+    private ReadData eqReadData() {
+        ArgumentMatcher<ReadData> matcher = new ArgumentMatcher<ReadData>() {
+            @Override
+            public boolean matches(Object argument) {
+                return (argument instanceof ReadData) &&
+                    ((ReadData)argument).getPath().equals(TestModel.TEST_PATH);
+            }
+        };
 
-        actorContext.setExecuteRemoteOperationResponse(new ReadDataReply(
-            TestModel.createTestContext(),ImmutableNodes.containerNode(TestModel.TEST_QNAME)).toSerializable());
+        return argThat(matcher);
+    }
 
-        read = transactionProxy.read(TestModel.TEST_PATH);
+    private WriteData eqLegacyWriteData(final NormalizedNode<?, ?> nodeToWrite) {
+        ArgumentMatcher<WriteData> matcher = new ArgumentMatcher<WriteData>() {
+            @Override
+            public boolean matches(Object argument) {
+                if(ShardTransactionMessages.WriteData.class.equals(argument.getClass())) {
+                    WriteData obj = WriteData.fromSerializable(argument);
+                    return obj.getPath().equals(TestModel.TEST_PATH) && obj.getData().equals(nodeToWrite);
+                }
 
-        normalizedNodeOptional = read.get();
+                return false;
+            }
+        };
 
-        Assert.assertTrue(normalizedNodeOptional.isPresent());
+        return argThat(matcher);
     }
 
-    @Test
-    public void testExists() throws Exception {
-        final Props props = Props.create(DoNothingActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+    private MergeData eqLegacyMergeData(final NormalizedNode<?, ?> nodeToWrite) {
+        ArgumentMatcher<MergeData> matcher = new ArgumentMatcher<MergeData>() {
+            @Override
+            public boolean matches(Object argument) {
+                if(ShardTransactionMessages.MergeData.class.equals(argument.getClass())) {
+                    MergeData obj = MergeData.fromSerializable(argument);
+                    return obj.getPath().equals(TestModel.TEST_PATH) && obj.getData().equals(nodeToWrite);
+                }
+
+                return false;
+            }
+        };
+
+        return argThat(matcher);
+    }
+
+    private DeleteData eqLegacyDeleteData(final YangInstanceIdentifier expPath) {
+        ArgumentMatcher<DeleteData> matcher = new ArgumentMatcher<DeleteData>() {
+            @Override
+            public boolean matches(Object argument) {
+                return ShardTransactionMessages.DeleteData.class.equals(argument.getClass()) &&
+                       DeleteData.fromSerializable(argument).getPath().equals(expPath);
+            }
+        };
+
+        return argThat(matcher);
+    }
+
+    private Future<Object> readySerializedTxReply(String path) {
+        return Futures.successful((Object)new ReadyTransactionReply(path).toSerializable());
+    }
+
+    private Future<Object> readyTxReply(String path) {
+        return Futures.successful((Object)new ReadyTransactionReply(path));
+    }
+
+    private Future<Object> readSerializedDataReply(NormalizedNode<?, ?> data,
+            short transactionVersion) {
+        return Futures.successful(new ReadDataReply(data, transactionVersion).toSerializable());
+    }
+
+    private Future<Object> readSerializedDataReply(NormalizedNode<?, ?> data) {
+        return readSerializedDataReply(data, DataStoreVersions.CURRENT_VERSION);
+    }
+
+    private Future<ReadDataReply> readDataReply(NormalizedNode<?, ?> data) {
+        return Futures.successful(new ReadDataReply(data, DataStoreVersions.CURRENT_VERSION));
+    }
+
+    private Future<Object> dataExistsSerializedReply(boolean exists) {
+        return Futures.successful(new DataExistsReply(exists).toSerializable());
+    }
+
+    private Future<DataExistsReply> dataExistsReply(boolean exists) {
+        return Futures.successful(new DataExistsReply(exists));
+    }
+
+    private Future<BatchedModificationsReply> batchedModificationsReply(int count) {
+        return Futures.successful(new BatchedModificationsReply(count));
+    }
+
+    private Future<Object> incompleteFuture(){
+        return mock(Future.class);
+    }
+
+    private ActorSelection actorSelection(ActorRef actorRef) {
+        return getSystem().actorSelection(actorRef.path());
+    }
+
+    private void expectBatchedModifications(ActorRef actorRef, int count) {
+        doReturn(batchedModificationsReply(count)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+    }
+
+    private void expectBatchedModifications(int count) {
+        doReturn(batchedModificationsReply(count)).when(mockActorContext).executeOperationAsync(
+                any(ActorSelection.class), isA(BatchedModifications.class));
+    }
+
+    private void expectIncompleteBatchedModifications() {
+        doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                any(ActorSelection.class), isA(BatchedModifications.class));
+    }
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+    private void expectReadyTransaction(ActorRef actorRef) {
+        doReturn(readySerializedTxReply(actorRef.path().toString())).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(ReadyTransaction.SERIALIZABLE_CLASS));
+    }
+
+    private void expectFailedBatchedModifications(ActorRef actorRef) {
+        doReturn(Futures.failed(new TestException())).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+    }
+
+    private CreateTransactionReply createTransactionReply(ActorRef actorRef, int transactionVersion){
+        return CreateTransactionReply.newBuilder()
+            .setTransactionActorPath(actorRef.path().toString())
+            .setTransactionId("txn-1")
+            .setMessageVersion(transactionVersion)
+            .build();
+    }
 
+    private ActorRef setupActorContextWithoutInitialCreateTransaction(ActorSystem actorSystem) {
+        ActorRef actorRef = actorSystem.actorOf(Props.create(DoNothingActor.class));
+        doReturn(actorSystem.actorSelection(actorRef.path())).
+                when(mockActorContext).actorSelection(actorRef.path().toString());
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        doReturn(Futures.successful(actorSystem.actorSelection(actorRef.path()))).
+                when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
 
+        doReturn(false).when(mockActorContext).isPathLocal(actorRef.path().toString());
 
-        actorContext.setExecuteRemoteOperationResponse(new DataExistsReply(false).toSerializable());
+        doReturn(10).when(mockActorContext).getTransactionOutstandingOperationLimit();
 
-        CheckedFuture<Boolean, ReadFailedException> exists =
-            transactionProxy.exists(TestModel.TEST_PATH);
+        return actorRef;
+    }
 
-        Assert.assertFalse(exists.checkedGet());
+    private ActorRef setupActorContextWithInitialCreateTransaction(ActorSystem actorSystem,
+            TransactionType type, int transactionVersion) {
+        ActorRef actorRef = setupActorContextWithoutInitialCreateTransaction(actorSystem);
 
-        actorContext.setExecuteRemoteOperationResponse(new DataExistsReply(true).toSerializable());
+        doReturn(Futures.successful(createTransactionReply(actorRef, transactionVersion))).when(mockActorContext).
+                executeOperationAsync(eq(actorSystem.actorSelection(actorRef.path())),
+                        eqCreateTransaction(memberName, type));
 
-        exists = transactionProxy.exists(TestModel.TEST_PATH);
+        return actorRef;
+    }
 
-        Assert.assertTrue(exists.checkedGet());
+    private ActorRef setupActorContextWithInitialCreateTransaction(ActorSystem actorSystem, TransactionType type) {
+        return setupActorContextWithInitialCreateTransaction(actorSystem, type, DataStoreVersions.CURRENT_VERSION);
+    }
 
-        actorContext.setExecuteRemoteOperationResponse("bad message");
 
-        exists = transactionProxy.exists(TestModel.TEST_PATH);
+    private void propagateReadFailedExceptionCause(CheckedFuture<?, ReadFailedException> future)
+            throws Throwable {
 
         try {
-            exists.checkedGet();
-            fail();
-        } catch(ReadFailedException e){
+            future.checkedGet(5, TimeUnit.SECONDS);
+            fail("Expected ReadFailedException");
+        } catch(ReadFailedException e) {
+            throw e.getCause();
         }
+    }
+
+    @Test
+    public void testRead() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
 
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
+
+        doReturn(readSerializedDataReply(null)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        Optional<NormalizedNode<?, ?>> readOptional = transactionProxy.read(
+                TestModel.TEST_PATH).get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", false, readOptional.isPresent());
+
+        NormalizedNode<?, ?> expectedNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        doReturn(readSerializedDataReply(expectedNode)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        readOptional = transactionProxy.read(TestModel.TEST_PATH).get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+
+        assertEquals("Response NormalizedNode", expectedNode, readOptional.get());
     }
 
     @Test(expected = ReadFailedException.class)
-    public void testReadWhenAnInvalidMessageIsSentInReply() throws Exception {
-        final Props props = Props.create(DoNothingActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+    public void testReadWithInvalidReplyMessageType() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+        doReturn(Futures.successful(new Object())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqSerializedReadData());
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
 
+        transactionProxy.read(TestModel.TEST_PATH).checkedGet(5, TimeUnit.SECONDS);
+    }
+
+    @Test(expected = TestException.class)
+    public void testReadWithAsyncRemoteOperatonFailure() throws Throwable {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
 
+        doReturn(Futures.failed(new TestException())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqSerializedReadData());
 
-        CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException>
-            read = transactionProxy.read(TestModel.TEST_PATH);
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
 
-        read.checkedGet();
+        propagateReadFailedExceptionCause(transactionProxy.read(TestModel.TEST_PATH));
     }
 
-    @Test
-    public void testReadWhenAPrimaryNotFoundExceptionIsThrown() throws Exception {
-        final ActorContext actorContext = mock(ActorContext.class);
+    private void testExceptionOnInitialCreateTransaction(Exception exToThrow, Invoker invoker)
+            throws Throwable {
+        ActorRef actorRef = getSystem().actorOf(Props.create(DoNothingActor.class));
+
+        if (exToThrow instanceof PrimaryNotFoundException) {
+            doReturn(Futures.failed(exToThrow)).when(mockActorContext).findPrimaryShardAsync(anyString());
+        } else {
+            doReturn(Futures.successful(getSystem().actorSelection(actorRef.path()))).
+                    when(mockActorContext).findPrimaryShardAsync(anyString());
+        }
+
+        doReturn(Futures.failed(exToThrow)).when(mockActorContext).executeOperationAsync(
+                any(ActorSelection.class), any());
 
-        when(actorContext.executeShardOperation(anyString(), any(), any(
-            FiniteDuration.class))).thenThrow(new PrimaryNotFoundException("test"));
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        propagateReadFailedExceptionCause(invoker.invoke(transactionProxy));
+    }
 
+    private void testReadWithExceptionOnInitialCreateTransaction(Exception exToThrow) throws Throwable {
+        testExceptionOnInitialCreateTransaction(exToThrow, new Invoker() {
+            @Override
+            public CheckedFuture<?, ReadFailedException> invoke(TransactionProxy proxy) throws Exception {
+                return proxy.read(TestModel.TEST_PATH);
+            }
+        });
+    }
 
-        ListenableFuture<Optional<NormalizedNode<?, ?>>> read =
-            transactionProxy.read(TestModel.TEST_PATH);
+    @Test(expected = PrimaryNotFoundException.class)
+    public void testReadWhenAPrimaryNotFoundExceptionIsThrown() throws Throwable {
+        testReadWithExceptionOnInitialCreateTransaction(new PrimaryNotFoundException("test"));
+    }
 
-        Assert.assertFalse(read.get().isPresent());
+    @Test(expected = TimeoutException.class)
+    public void testReadWhenATimeoutExceptionIsThrown() throws Throwable {
+        testReadWithExceptionOnInitialCreateTransaction(new TimeoutException("test",
+                new Exception("reason")));
+    }
 
+    @Test(expected = TestException.class)
+    public void testReadWhenAnyOtherExceptionIsThrown() throws Throwable {
+        testReadWithExceptionOnInitialCreateTransaction(new TestException());
     }
 
+    @Test(expected = TestException.class)
+    public void testReadWithPriorRecordingOperationFailure() throws Throwable {
+        doReturn(dataStoreContextBuilder.shardBatchedModificationCount(2).build()).
+                when(mockActorContext).getDatastoreContext();
+
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectFailedBatchedModifications(actorRef);
+
+        doReturn(readSerializedDataReply(null)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        transactionProxy.delete(TestModel.TEST_PATH);
+
+        try {
+            propagateReadFailedExceptionCause(transactionProxy.read(TestModel.TEST_PATH));
+        } finally {
+            verify(mockActorContext, times(0)).executeOperationAsync(
+                    eq(actorSelection(actorRef)), eqSerializedReadData());
+        }
+    }
 
     @Test
-    public void testReadWhenATimeoutExceptionIsThrown() throws Exception {
-        final ActorContext actorContext = mock(ActorContext.class);
+    public void testReadWithPriorRecordingOperationSuccessful() throws Throwable {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        NormalizedNode<?, ?> expectedNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectBatchedModifications(actorRef, 1);
 
-        when(actorContext.executeShardOperation(anyString(), any(), any(
-            FiniteDuration.class))).thenThrow(new TimeoutException("test", new Exception("reason")));
+        doReturn(readSerializedDataReply(expectedNode)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
 
+        transactionProxy.write(TestModel.TEST_PATH, expectedNode);
 
-        ListenableFuture<Optional<NormalizedNode<?, ?>>> read =
-            transactionProxy.read(TestModel.TEST_PATH);
+        Optional<NormalizedNode<?, ?>> readOptional = transactionProxy.read(
+                TestModel.TEST_PATH).get(5, TimeUnit.SECONDS);
 
-        Assert.assertFalse(read.get().isPresent());
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+        assertEquals("Response NormalizedNode", expectedNode, readOptional.get());
 
+        InOrder inOrder = Mockito.inOrder(mockActorContext);
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+    }
+
+    @Test(expected=IllegalStateException.class)
+    public void testReadPreConditionCheck() {
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+        transactionProxy.read(TestModel.TEST_PATH);
+    }
+
+    @Test(expected=IllegalArgumentException.class)
+    public void testInvalidCreateTransactionReply() throws Throwable {
+        ActorRef actorRef = getSystem().actorOf(Props.create(DoNothingActor.class));
+
+        doReturn(getSystem().actorSelection(actorRef.path())).when(mockActorContext).
+            actorSelection(actorRef.path().toString());
+
+        doReturn(Futures.successful(getSystem().actorSelection(actorRef.path()))).
+            when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+
+        doReturn(Futures.successful(new Object())).when(mockActorContext).executeOperationAsync(
+            eq(getSystem().actorSelection(actorRef.path())), eqCreateTransaction(memberName, READ_ONLY));
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
+
+        propagateReadFailedExceptionCause(transactionProxy.read(TestModel.TEST_PATH));
     }
 
     @Test
-    public void testReadWhenAAnyOtherExceptionIsThrown() throws Exception {
-        final ActorContext actorContext = mock(ActorContext.class);
+    public void testExists() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
 
-        when(actorContext.executeShardOperation(anyString(), any(), any(
-            FiniteDuration.class))).thenThrow(new NullPointerException());
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        doReturn(dataExistsSerializedReply(false)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
 
+        Boolean exists = transactionProxy.exists(TestModel.TEST_PATH).checkedGet();
 
-        try {
-            ListenableFuture<Optional<NormalizedNode<?, ?>>> read =
-                transactionProxy.read(TestModel.TEST_PATH);
-            fail("A null pointer exception was expected");
-        } catch(NullPointerException e){
+        assertEquals("Exists response", false, exists);
+
+        doReturn(dataExistsSerializedReply(true)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        exists = transactionProxy.exists(TestModel.TEST_PATH).checkedGet();
 
+        assertEquals("Exists response", true, exists);
+    }
+
+    @Test(expected = PrimaryNotFoundException.class)
+    public void testExistsWhenAPrimaryNotFoundExceptionIsThrown() throws Throwable {
+        testExceptionOnInitialCreateTransaction(new PrimaryNotFoundException("test"), new Invoker() {
+            @Override
+            public CheckedFuture<?, ReadFailedException> invoke(TransactionProxy proxy) throws Exception {
+                return proxy.exists(TestModel.TEST_PATH);
+            }
+        });
+    }
+
+    @Test(expected = ReadFailedException.class)
+    public void testExistsWithInvalidReplyMessageType() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
+
+        doReturn(Futures.successful(new Object())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext,
+                READ_ONLY);
+
+        transactionProxy.exists(TestModel.TEST_PATH).checkedGet(5, TimeUnit.SECONDS);
+    }
+
+    @Test(expected = TestException.class)
+    public void testExistsWithAsyncRemoteOperatonFailure() throws Throwable {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
+
+        doReturn(Futures.failed(new TestException())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
+
+        propagateReadFailedExceptionCause(transactionProxy.exists(TestModel.TEST_PATH));
+    }
+
+    @Test(expected = TestException.class)
+    public void testExistsWithPriorRecordingOperationFailure() throws Throwable {
+        doReturn(dataStoreContextBuilder.shardBatchedModificationCount(2).build()).
+                when(mockActorContext).getDatastoreContext();
+
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectFailedBatchedModifications(actorRef);
+
+        doReturn(dataExistsSerializedReply(false)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext,
+                READ_WRITE);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        transactionProxy.delete(TestModel.TEST_PATH);
+
+        try {
+            propagateReadFailedExceptionCause(transactionProxy.exists(TestModel.TEST_PATH));
+        } finally {
+            verify(mockActorContext, times(0)).executeOperationAsync(
+                    eq(actorSelection(actorRef)), eqSerializedDataExists());
         }
     }
 
+    @Test
+    public void testExistsWithPriorRecordingOperationSuccessful() throws Throwable {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectBatchedModifications(actorRef, 1);
+
+        doReturn(dataExistsSerializedReply(true)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        Boolean exists = transactionProxy.exists(TestModel.TEST_PATH).checkedGet();
+
+        assertEquals("Exists response", true, exists);
+
+        InOrder inOrder = Mockito.inOrder(mockActorContext);
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+    }
+
+    @Test(expected=IllegalStateException.class)
+    public void testExistsPreConditionCheck() {
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+        transactionProxy.exists(TestModel.TEST_PATH);
+    }
 
+    private void verifyRecordingOperationFutures(List<Future<Object>> futures,
+            Class<?>... expResultTypes) throws Exception {
+        assertEquals("getRecordingOperationFutures size", expResultTypes.length, futures.size());
+
+        int i = 0;
+        for( Future<Object> future: futures) {
+            assertNotNull("Recording operation Future is null", future);
+
+            Class<?> expResultType = expResultTypes[i++];
+            if(Throwable.class.isAssignableFrom(expResultType)) {
+                try {
+                    Await.result(future, Duration.create(5, TimeUnit.SECONDS));
+                    fail("Expected exception from recording operation Future");
+                } catch(Exception e) {
+                    // Expected
+                }
+            } else {
+                assertEquals(String.format("Recording operation %d Future result type", i +1 ), expResultType,
+                             Await.result(future, Duration.create(5, TimeUnit.SECONDS)).getClass());
+            }
+        }
+    }
 
     @Test
     public void testWrite() throws Exception {
-        final Props props = Props.create(MessageCollectorActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        expectBatchedModifications(actorRef, 1);
+        expectReadyTransaction(actorRef);
 
-        transactionProxy.write(TestModel.TEST_PATH,
-            ImmutableNodes.containerNode(TestModel.NAME_QNAME));
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
 
-        Object messages = testContext
-            .executeLocalOperation(actorRef, "messages",
-                ActorContext.ASK_DURATION);
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
 
-        Assert.assertNotNull(messages);
+        // This sends the batched modification.
+        transactionProxy.ready();
 
-        Assert.assertTrue(messages instanceof List);
+        verifyOneBatchedModification(actorRef, new WriteModification(TestModel.TEST_PATH, nodeToWrite));
 
-        List<Object> listMessages = (List<Object>) messages;
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+    }
+
+    @Test
+    public void testWriteAfterAsyncRead() throws Throwable {
+        ActorRef actorRef = setupActorContextWithoutInitialCreateTransaction(getSystem());
+
+        Promise<Object> createTxPromise = akka.dispatch.Futures.promise();
+        doReturn(createTxPromise).when(mockActorContext).executeOperationAsync(
+                eq(getSystem().actorSelection(actorRef.path())),
+                eqCreateTransaction(memberName, READ_WRITE));
+
+        doReturn(readSerializedDataReply(null)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        expectBatchedModifications(actorRef, 1);
+        expectReadyTransaction(actorRef);
+
+        final NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        final TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        final CountDownLatch readComplete = new CountDownLatch(1);
+        final AtomicReference<Throwable> caughtEx = new AtomicReference<>();
+        com.google.common.util.concurrent.Futures.addCallback(transactionProxy.read(TestModel.TEST_PATH),
+                new  FutureCallback<Optional<NormalizedNode<?, ?>>>() {
+                    @Override
+                    public void onSuccess(Optional<NormalizedNode<?, ?>> result) {
+                        try {
+                            transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+                        } catch (Exception e) {
+                            caughtEx.set(e);
+                        } finally {
+                            readComplete.countDown();
+                        }
+                    }
+
+                    @Override
+                    public void onFailure(Throwable t) {
+                        caughtEx.set(t);
+                        readComplete.countDown();
+                    }
+                });
+
+        createTxPromise.success(createTransactionReply(actorRef, DataStoreVersions.CURRENT_VERSION));
+
+        Uninterruptibles.awaitUninterruptibly(readComplete, 5, TimeUnit.SECONDS);
+
+        if(caughtEx.get() != null) {
+            throw caughtEx.get();
+        }
 
-        Assert.assertEquals(1, listMessages.size());
+        // This sends the batched modification.
+        transactionProxy.ready();
 
-        Assert.assertEquals(WriteData.SERIALIZABLE_CLASS, listMessages.get(0).getClass());
+        verifyOneBatchedModification(actorRef, new WriteModification(TestModel.TEST_PATH, nodeToWrite));
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+    }
+
+    @Test(expected=IllegalStateException.class)
+    public void testWritePreConditionCheck() {
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_ONLY);
+        transactionProxy.write(TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
     }
 
-    private Object createPrimaryFound(ActorRef actorRef) {
-        return new PrimaryFound(actorRef.path().toString()).toSerializable();
+    @Test(expected=IllegalStateException.class)
+    public void testWriteAfterReadyPreConditionCheck() {
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+
+        transactionProxy.ready();
+
+        transactionProxy.write(TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
     }
 
     @Test
     public void testMerge() throws Exception {
-        final Props props = Props.create(MessageCollectorActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectBatchedModifications(actorRef, 1);
+        expectReadyTransaction(actorRef);
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+        transactionProxy.merge(TestModel.TEST_PATH, nodeToWrite);
+
+        // This sends the batched modification.
+        transactionProxy.ready();
+
+        verifyOneBatchedModification(actorRef, new MergeModification(TestModel.TEST_PATH, nodeToWrite));
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+    }
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+    @Test
+    public void testDelete() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
 
-        transactionProxy.merge(TestModel.TEST_PATH,
-            ImmutableNodes.containerNode(TestModel.NAME_QNAME));
+        expectBatchedModifications(actorRef, 1);
+        expectReadyTransaction(actorRef);
 
-        Object messages = testContext
-            .executeLocalOperation(actorRef, "messages",
-                ActorContext.ASK_DURATION);
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
 
-        Assert.assertNotNull(messages);
+        transactionProxy.delete(TestModel.TEST_PATH);
 
-        Assert.assertTrue(messages instanceof List);
+        // This sends the batched modification.
+        transactionProxy.ready();
 
-        List<Object> listMessages = (List<Object>) messages;
+        verifyOneBatchedModification(actorRef, new DeleteModification(TestModel.TEST_PATH));
 
-        Assert.assertEquals(1, listMessages.size());
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+    }
 
-        Assert.assertEquals(MergeData.SERIALIZABLE_CLASS, listMessages.get(0).getClass());
+    private void verifyCohortFutures(ThreePhaseCommitCohortProxy proxy,
+        Object... expReplies) throws Exception {
+        assertEquals("getReadyOperationFutures size", expReplies.length,
+                proxy.getCohortFutures().size());
+
+        int i = 0;
+        for( Future<ActorSelection> future: proxy.getCohortFutures()) {
+            assertNotNull("Ready operation Future is null", future);
+
+            Object expReply = expReplies[i++];
+            if(expReply instanceof ActorSelection) {
+                ActorSelection actual = Await.result(future, Duration.create(5, TimeUnit.SECONDS));
+                assertEquals("Cohort actor path", expReply, actual);
+            } else {
+                // Expecting exception.
+                try {
+                    Await.result(future, Duration.create(5, TimeUnit.SECONDS));
+                    fail("Expected exception from ready operation Future");
+                } catch(Exception e) {
+                    // Expected
+                }
+            }
+        }
     }
 
     @Test
-    public void testDelete() throws Exception {
-        final Props props = Props.create(MessageCollectorActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+    public void testReady() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+        doReturn(readSerializedDataReply(null)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        expectBatchedModifications(actorRef, 1);
+        expectReadyTransaction(actorRef);
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.read(TestModel.TEST_PATH);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
+
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
+
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+
+        verifyCohortFutures(proxy, getSystem().actorSelection(actorRef.path()));
+
+        verify(mockActorContext).executeOperationAsync(eq(actorSelection(actorRef)),
+                isA(BatchedModifications.class));
+    }
+
+    private ActorRef testCompatibilityWithHeliumVersion(short version) throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(),
+                READ_WRITE, version);
+
+        NormalizedNode<?, ?> testNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        doReturn(readSerializedDataReply(testNode, version)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        doReturn(Futures.successful(new WriteDataReply().toSerializable(version))).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqLegacyWriteData(testNode));
+
+        doReturn(Futures.successful(new MergeDataReply().toSerializable(version))).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqLegacyMergeData(testNode));
+
+        doReturn(Futures.successful(new DeleteDataReply().toSerializable(version))).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)), eqLegacyDeleteData(TestModel.TEST_PATH));
+
+        expectReadyTransaction(actorRef);
+
+        doReturn(actorRef.path().toString()).when(mockActorContext).resolvePath(eq(actorRef.path().toString()),
+                eq(actorRef.path().toString()));
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        Optional<NormalizedNode<?, ?>> readOptional = transactionProxy.read(TestModel.TEST_PATH).
+                get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+        assertEquals("Response NormalizedNode", testNode, readOptional.get());
+
+        transactionProxy.write(TestModel.TEST_PATH, testNode);
+
+        transactionProxy.merge(TestModel.TEST_PATH, testNode);
 
         transactionProxy.delete(TestModel.TEST_PATH);
 
-        Object messages = testContext
-            .executeLocalOperation(actorRef, "messages",
-                ActorContext.ASK_DURATION);
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
 
-        Assert.assertNotNull(messages);
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
 
-        Assert.assertTrue(messages instanceof List);
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
 
-        List<Object> listMessages = (List<Object>) messages;
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                ShardTransactionMessages.WriteDataReply.class, ShardTransactionMessages.MergeDataReply.class,
+                ShardTransactionMessages.DeleteDataReply.class);
 
-        Assert.assertEquals(1, listMessages.size());
+        verifyCohortFutures(proxy, getSystem().actorSelection(actorRef.path()));
 
-        Assert.assertEquals(DeleteData.SERIALIZABLE_CLASS, listMessages.get(0).getClass());
+        return actorRef;
     }
 
     @Test
-    public void testReady() throws Exception {
-        final Props props = Props.create(DoNothingActor.class);
-        final ActorRef doNothingActorRef = getSystem().actorOf(props);
+    public void testCompatibilityWithBaseHeliumVersion() throws Exception {
+        ActorRef actorRef = testCompatibilityWithHeliumVersion(DataStoreVersions.BASE_HELIUM_VERSION);
+
+        verify(mockActorContext).resolvePath(eq(actorRef.path().toString()),
+                eq(actorRef.path().toString()));
+    }
+
+    @Test
+    public void testCompatibilityWithHeliumR1Version() throws Exception {
+        ActorRef actorRef = testCompatibilityWithHeliumVersion(DataStoreVersions.HELIUM_1_VERSION);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(doNothingActorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(doNothingActorRef));
-        actorContext.setExecuteRemoteOperationResponse(new ReadyTransactionReply(doNothingActorRef.path()).toSerializable());
+        verify(mockActorContext, Mockito.never()).resolvePath(eq(actorRef.path().toString()),
+                eq(actorRef.path().toString()));
+    }
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+    @Test
+    public void testReadyWithRecordingOperationFailure() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
 
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
 
-        transactionProxy.read(TestModel.TEST_PATH);
+        expectFailedBatchedModifications(actorRef);
+
+        expectReadyTransaction(actorRef);
+
+        doReturn(false).when(mockActorContext).isPathLocal(actorRef.path().toString());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
 
         DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
 
-        Assert.assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
 
         ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
 
-        Assert.assertTrue("No cohort paths returned", proxy.getCohortPaths().size() > 0);
+        verifyCohortFutures(proxy, TestException.class);
 
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(), TestException.class);
     }
 
     @Test
-    public void testGetIdentifier(){
-        final Props props = Props.create(DoNothingActor.class);
-        final ActorRef doNothingActorRef = getSystem().actorOf(props);
+    public void testReadyWithReplyFailure() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectBatchedModifications(actorRef, 1);
+
+        doReturn(Futures.failed(new TestException())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)),
+                        isA(ReadyTransaction.SERIALIZABLE_CLASS));
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+
+        transactionProxy.merge(TestModel.TEST_PATH, nodeToWrite);
+
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
+
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteShardOperationResponse( createTransactionReply(doNothingActorRef) );
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
 
-        Assert.assertNotNull(transactionProxy.getIdentifier());
+        verifyCohortFutures(proxy, TestException.class);
     }
 
     @Test
-    public void testClose(){
-        final Props props = Props.create(MessageCollectorActor.class);
-        final ActorRef actorRef = getSystem().actorOf(props);
+    public void testReadyWithInitialCreateTransactionFailure() throws Exception {
 
-        final MockActorContext actorContext = new MockActorContext(this.getSystem());
-        actorContext.setExecuteLocalOperationResponse(createPrimaryFound(actorRef));
-        actorContext.setExecuteShardOperationResponse(createTransactionReply(actorRef));
-        actorContext.setExecuteRemoteOperationResponse("message");
+        doReturn(Futures.failed(new PrimaryNotFoundException("mock"))).when(
+                mockActorContext).findPrimaryShardAsync(anyString());
 
-        TransactionProxy transactionProxy =
-            new TransactionProxy(actorContext,
-                TransactionProxy.TransactionType.READ_ONLY, transactionExecutor, TestModel.createTestContext());
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
 
-        transactionProxy.read(TestModel.TEST_PATH);
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
 
-        transactionProxy.close();
+        transactionProxy.merge(TestModel.TEST_PATH, nodeToWrite);
 
-        Object messages = testContext
-            .executeLocalOperation(actorRef, "messages",
-                ActorContext.ASK_DURATION);
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
 
-        Assert.assertNotNull(messages);
+        transactionProxy.delete(TestModel.TEST_PATH);
 
-        Assert.assertTrue(messages instanceof List);
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
 
-        List<Object> listMessages = (List<Object>) messages;
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
 
-        Assert.assertEquals(1, listMessages.size());
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
 
-        Assert.assertTrue(listMessages.get(0).getClass().equals(CloseTransaction.SERIALIZABLE_CLASS));
+        verifyCohortFutures(proxy, PrimaryNotFoundException.class);
     }
 
-    private CreateTransactionReply createTransactionReply(ActorRef actorRef){
-        return CreateTransactionReply.newBuilder()
-            .setTransactionActorPath(actorRef.path().toString())
-            .setTransactionId("txn-1")
-            .build();
+    @Test
+    public void testReadyWithInvalidReplyMessageType() throws Exception {
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), WRITE_ONLY);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        expectBatchedModifications(actorRef, 1);
+
+        doReturn(Futures.successful(new Object())).when(mockActorContext).
+                executeOperationAsync(eq(actorSelection(actorRef)),
+                        isA(ReadyTransaction.SERIALIZABLE_CLASS));
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
+
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
+
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
+
+        verifyCohortFutures(proxy, IllegalArgumentException.class);
+    }
+
+    @Test
+    public void testUnusedTransaction() throws Exception {
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
+
+        assertEquals("canCommit", true, ready.canCommit().get());
+        ready.preCommit().get();
+        ready.commit().get();
+    }
+
+    @Test
+    public void testGetIdentifier() {
+        setupActorContextWithInitialCreateTransaction(getSystem(), READ_ONLY);
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext,
+                TransactionProxy.TransactionType.READ_ONLY);
+
+        Object id = transactionProxy.getIdentifier();
+        assertNotNull("getIdentifier returned null", id);
+        assertTrue("Invalid identifier: " + id, id.toString().startsWith(memberName));
+    }
+
+    @Test
+    public void testClose() throws Exception{
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        doReturn(readSerializedDataReply(null)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.read(TestModel.TEST_PATH);
+
+        transactionProxy.close();
+
+        verify(mockActorContext).sendOperationAsync(
+                eq(actorSelection(actorRef)), isA(CloseTransaction.SERIALIZABLE_CLASS));
+    }
+
+
+    /**
+     * Method to test a local Tx actor. The Tx paths are matched to decide if the
+     * Tx actor is local or not. This is done by mocking the Tx actor path
+     * and the caller paths and ensuring that the paths have the remote-address format
+     *
+     * Note: Since the default akka provider for test is not a RemoteActorRefProvider,
+     * the paths returned for the actors for all the tests are not qualified remote paths.
+     * Hence are treated as non-local/remote actors. In short, all tests except
+     * few below run for remote actors
+     *
+     * @throws Exception
+     */
+    @Test
+    public void testLocalTxActorRead() throws Exception {
+        ActorSystem actorSystem = getSystem();
+        ActorRef shardActorRef = actorSystem.actorOf(Props.create(DoNothingActor.class));
+
+        doReturn(actorSystem.actorSelection(shardActorRef.path())).
+            when(mockActorContext).actorSelection(shardActorRef.path().toString());
+
+        doReturn(Futures.successful(actorSystem.actorSelection(shardActorRef.path()))).
+            when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+
+        String actorPath = "akka.tcp://system@127.0.0.1:2550/user/tx-actor";
+        CreateTransactionReply createTransactionReply = CreateTransactionReply.newBuilder()
+            .setTransactionId("txn-1").setTransactionActorPath(actorPath).build();
+
+        doReturn(Futures.successful(createTransactionReply)).when(mockActorContext).
+            executeOperationAsync(eq(actorSystem.actorSelection(shardActorRef.path())),
+                eqCreateTransaction(memberName, READ_ONLY));
+
+        doReturn(true).when(mockActorContext).isPathLocal(actorPath);
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext,READ_ONLY);
+
+        // negative test case with null as the reply
+        doReturn(readDataReply(null)).when(mockActorContext).executeOperationAsync(
+            any(ActorSelection.class), eqReadData());
+
+        Optional<NormalizedNode<?, ?>> readOptional = transactionProxy.read(
+            TestModel.TEST_PATH).get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", false, readOptional.isPresent());
+
+        // test case with node as read data reply
+        NormalizedNode<?, ?> expectedNode = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        doReturn(readDataReply(expectedNode)).when(mockActorContext).executeOperationAsync(
+            any(ActorSelection.class), eqReadData());
+
+        readOptional = transactionProxy.read(TestModel.TEST_PATH).get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+
+        assertEquals("Response NormalizedNode", expectedNode, readOptional.get());
+
+        // test for local data exists
+        doReturn(dataExistsReply(true)).when(mockActorContext).executeOperationAsync(
+            any(ActorSelection.class), eqDataExists());
+
+        boolean exists = transactionProxy.exists(TestModel.TEST_PATH).checkedGet();
+
+        assertEquals("Exists response", true, exists);
+    }
+
+    @Test
+    public void testLocalTxActorReady() throws Exception {
+        ActorSystem actorSystem = getSystem();
+        ActorRef shardActorRef = actorSystem.actorOf(Props.create(DoNothingActor.class));
+
+        doReturn(actorSystem.actorSelection(shardActorRef.path())).
+            when(mockActorContext).actorSelection(shardActorRef.path().toString());
+
+        doReturn(Futures.successful(actorSystem.actorSelection(shardActorRef.path()))).
+            when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+
+        String actorPath = "akka.tcp://system@127.0.0.1:2550/user/tx-actor";
+        CreateTransactionReply createTransactionReply = CreateTransactionReply.newBuilder().
+            setTransactionId("txn-1").setTransactionActorPath(actorPath).
+            setMessageVersion(DataStoreVersions.CURRENT_VERSION).build();
+
+        doReturn(Futures.successful(createTransactionReply)).when(mockActorContext).
+            executeOperationAsync(eq(actorSystem.actorSelection(shardActorRef.path())),
+                eqCreateTransaction(memberName, WRITE_ONLY));
+
+        doReturn(true).when(mockActorContext).isPathLocal(actorPath);
+
+        doReturn(batchedModificationsReply(1)).when(mockActorContext).executeOperationAsync(
+                any(ActorSelection.class), isA(BatchedModifications.class));
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, WRITE_ONLY);
+
+        NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+        transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class);
+
+        // testing ready
+        doReturn(readyTxReply(shardActorRef.path().toString())).when(mockActorContext).executeOperationAsync(
+            any(ActorSelection.class), isA(ReadyTransaction.class));
+
+        DOMStoreThreePhaseCommitCohort ready = transactionProxy.ready();
+
+        assertTrue(ready instanceof ThreePhaseCommitCohortProxy);
+
+        ThreePhaseCommitCohortProxy proxy = (ThreePhaseCommitCohortProxy) ready;
+
+        verifyCohortFutures(proxy, getSystem().actorSelection(shardActorRef.path()));
+    }
+
+    private static interface TransactionProxyOperation {
+        void run(TransactionProxy transactionProxy);
+    }
+
+    private void throttleOperation(TransactionProxyOperation operation) {
+        throttleOperation(operation, 1, true);
+    }
+
+    private void throttleOperation(TransactionProxyOperation operation, int outstandingOpsLimit, boolean shardFound){
+        ActorSystem actorSystem = getSystem();
+        ActorRef shardActorRef = actorSystem.actorOf(Props.create(DoNothingActor.class));
+
+        doReturn(outstandingOpsLimit).when(mockActorContext).getTransactionOutstandingOperationLimit();
+
+        doReturn(actorSystem.actorSelection(shardActorRef.path())).
+                when(mockActorContext).actorSelection(shardActorRef.path().toString());
+
+        if(shardFound) {
+            doReturn(Futures.successful(actorSystem.actorSelection(shardActorRef.path()))).
+                    when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+        } else {
+            doReturn(Futures.failed(new Exception("not found")))
+                    .when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+        }
+
+        String actorPath = "akka.tcp://system@127.0.0.1:2550/user/tx-actor";
+        CreateTransactionReply createTransactionReply = CreateTransactionReply.newBuilder().
+                setTransactionId("txn-1").setTransactionActorPath(actorPath).
+                setMessageVersion(DataStoreVersions.CURRENT_VERSION).build();
+
+        doReturn(Futures.successful(createTransactionReply)).when(mockActorContext).
+                executeOperationAsync(eq(actorSystem.actorSelection(shardActorRef.path())),
+                        eqCreateTransaction(memberName, READ_WRITE));
+
+        doReturn(true).when(mockActorContext).isPathLocal(actorPath);
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        long start = System.nanoTime();
+
+        operation.run(transactionProxy);
+
+        long end = System.nanoTime();
+
+        long expected = TimeUnit.SECONDS.toNanos(mockActorContext.getDatastoreContext().getOperationTimeoutInSeconds());
+        Assert.assertTrue(String.format("Expected elapsed time: %s. Actual: %s",
+                expected, (end-start)), (end - start) > expected);
+
+    }
+
+    private void completeOperation(TransactionProxyOperation operation){
+        completeOperation(operation, true);
+    }
+
+    private void completeOperation(TransactionProxyOperation operation, boolean shardFound){
+        ActorSystem actorSystem = getSystem();
+        ActorRef shardActorRef = actorSystem.actorOf(Props.create(DoNothingActor.class));
+
+        doReturn(1).when(mockActorContext).getTransactionOutstandingOperationLimit();
+
+        doReturn(actorSystem.actorSelection(shardActorRef.path())).
+                when(mockActorContext).actorSelection(shardActorRef.path().toString());
+
+        if(shardFound) {
+            doReturn(Futures.successful(actorSystem.actorSelection(shardActorRef.path()))).
+                    when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+        } else {
+            doReturn(Futures.failed(new Exception("not found")))
+                    .when(mockActorContext).findPrimaryShardAsync(eq(DefaultShardStrategy.DEFAULT_SHARD));
+        }
+
+        String actorPath = "akka.tcp://system@127.0.0.1:2550/user/tx-actor";
+        CreateTransactionReply createTransactionReply = CreateTransactionReply.newBuilder().
+                setTransactionId("txn-1").setTransactionActorPath(actorPath).
+                setMessageVersion(DataStoreVersions.CURRENT_VERSION).build();
+
+        doReturn(Futures.successful(createTransactionReply)).when(mockActorContext).
+                executeOperationAsync(eq(actorSystem.actorSelection(shardActorRef.path())),
+                        eqCreateTransaction(memberName, READ_WRITE));
+
+        doReturn(true).when(mockActorContext).isPathLocal(actorPath);
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        long start = System.nanoTime();
+
+        operation.run(transactionProxy);
+
+        long end = System.nanoTime();
+
+        long expected = TimeUnit.SECONDS.toNanos(mockActorContext.getDatastoreContext().getOperationTimeoutInSeconds());
+        Assert.assertTrue(String.format("Expected elapsed time: %s. Actual: %s",
+                expected, (end-start)), (end - start) <= expected);
+    }
+
+    public void testWriteThrottling(boolean shardFound){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(2);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+            }
+        }, 1, shardFound);
+    }
+
+    @Test
+    public void testWriteThrottlingWhenShardFound(){
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectIncompleteBatchedModifications();
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+            }
+        });
+    }
+
+    @Test
+    public void testWriteThrottlingWhenShardNotFound(){
+        // Confirm that there is no throttling when the Shard is not found
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(2);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+            }
+        }, false);
+
+    }
+
+
+    @Test
+    public void testWriteCompletion(){
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(2);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+            }
+        });
+    }
+
+    @Test
+    public void testMergeThrottlingWhenShardFound(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToMerge = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectIncompleteBatchedModifications();
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+            }
+        });
+    }
+
+    @Test
+    public void testMergeThrottlingWhenShardNotFound(){
+
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToMerge = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(2);
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+            }
+        }, false);
+    }
+
+    @Test
+    public void testMergeCompletion(){
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToMerge = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(2);
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+
+                transactionProxy.merge(TestModel.TEST_PATH, nodeToMerge);
+            }
+        });
+
+    }
+
+    @Test
+    public void testDeleteThrottlingWhenShardFound(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                expectIncompleteBatchedModifications();
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+            }
+        });
+    }
+
+
+    @Test
+    public void testDeleteThrottlingWhenShardNotFound(){
+
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                expectBatchedModifications(2);
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+            }
+        }, false);
+    }
+
+    @Test
+    public void testDeleteCompletion(){
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                expectBatchedModifications(2);
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+
+                transactionProxy.delete(TestModel.TEST_PATH);
+            }
+        });
+
+    }
+
+    @Test
+    public void testReadThrottlingWhenShardFound(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqReadData());
+
+                transactionProxy.read(TestModel.TEST_PATH);
+
+                transactionProxy.read(TestModel.TEST_PATH);
+            }
+        });
+    }
+
+    @Test
+    public void testReadThrottlingWhenShardNotFound(){
+
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqReadData());
+
+                transactionProxy.read(TestModel.TEST_PATH);
+
+                transactionProxy.read(TestModel.TEST_PATH);
+            }
+        }, false);
+    }
+
+
+    @Test
+    public void testReadCompletion(){
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToRead = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                doReturn(readDataReply(nodeToRead)).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqReadData());
+
+                transactionProxy.read(TestModel.TEST_PATH);
+
+                transactionProxy.read(TestModel.TEST_PATH);
+            }
+        });
+
+    }
+
+    @Test
+    public void testExistsThrottlingWhenShardFound(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqDataExists());
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+            }
+        });
+    }
+
+    @Test
+    public void testExistsThrottlingWhenShardNotFound(){
+
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqDataExists());
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+            }
+        }, false);
+    }
+
+
+    @Test
+    public void testExistsCompletion(){
+        completeOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                doReturn(dataExistsReply(true)).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), eqDataExists());
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+
+                transactionProxy.exists(TestModel.TEST_PATH);
+            }
+        });
+
+    }
+
+    @Test
+    public void testReadyThrottling(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+                expectBatchedModifications(1);
+
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), any(ReadyTransaction.class));
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.ready();
+            }
+        });
+    }
+
+    @Test
+    public void testReadyThrottlingWithTwoTransactionContexts(){
+
+        throttleOperation(new TransactionProxyOperation() {
+            @Override
+            public void run(TransactionProxy transactionProxy) {
+                NormalizedNode<?, ?> nodeToWrite = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+                NormalizedNode<?, ?> carsNode = ImmutableNodes.containerNode(CarsModel.BASE_QNAME);
+
+                expectBatchedModifications(2);
+
+                doReturn(incompleteFuture()).when(mockActorContext).executeOperationAsync(
+                        any(ActorSelection.class), any(ReadyTransaction.class));
+
+                transactionProxy.write(TestModel.TEST_PATH, nodeToWrite);
+
+                transactionProxy.write(TestModel.TEST_PATH, carsNode);
+
+                transactionProxy.ready();
+            }
+        }, 2, true);
+    }
+
+    @Test
+    public void testModificationOperationBatching() throws Throwable {
+        int shardBatchedModificationCount = 3;
+        doReturn(dataStoreContextBuilder.shardBatchedModificationCount(shardBatchedModificationCount).build()).
+                when(mockActorContext).getDatastoreContext();
+
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        expectBatchedModifications(actorRef, shardBatchedModificationCount);
+
+        expectReadyTransaction(actorRef);
+
+        YangInstanceIdentifier writePath1 = TestModel.TEST_PATH;
+        NormalizedNode<?, ?> writeNode1 = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        YangInstanceIdentifier writePath2 = TestModel.OUTER_LIST_PATH;
+        NormalizedNode<?, ?> writeNode2 = ImmutableNodes.containerNode(TestModel.OUTER_LIST_QNAME);
+
+        YangInstanceIdentifier writePath3 = TestModel.INNER_LIST_PATH;
+        NormalizedNode<?, ?> writeNode3 = ImmutableNodes.containerNode(TestModel.INNER_LIST_QNAME);
+
+        YangInstanceIdentifier mergePath1 = TestModel.TEST_PATH;
+        NormalizedNode<?, ?> mergeNode1 = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        YangInstanceIdentifier mergePath2 = TestModel.OUTER_LIST_PATH;
+        NormalizedNode<?, ?> mergeNode2 = ImmutableNodes.containerNode(TestModel.OUTER_LIST_QNAME);
+
+        YangInstanceIdentifier mergePath3 = TestModel.INNER_LIST_PATH;
+        NormalizedNode<?, ?> mergeNode3 = ImmutableNodes.containerNode(TestModel.INNER_LIST_QNAME);
+
+        YangInstanceIdentifier deletePath1 = TestModel.TEST_PATH;
+        YangInstanceIdentifier deletePath2 = TestModel.OUTER_LIST_PATH;
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.write(writePath1, writeNode1);
+        transactionProxy.write(writePath2, writeNode2);
+        transactionProxy.delete(deletePath1);
+        transactionProxy.merge(mergePath1, mergeNode1);
+        transactionProxy.merge(mergePath2, mergeNode2);
+        transactionProxy.write(writePath3, writeNode3);
+        transactionProxy.merge(mergePath3, mergeNode3);
+        transactionProxy.delete(deletePath2);
+
+        // This sends the last batch.
+        transactionProxy.ready();
+
+        List<BatchedModifications> batchedModifications = captureBatchedModifications(actorRef);
+        assertEquals("Captured BatchedModifications count", 3, batchedModifications.size());
+
+        verifyBatchedModifications(batchedModifications.get(0), new WriteModification(writePath1, writeNode1),
+                new WriteModification(writePath2, writeNode2), new DeleteModification(deletePath1));
+
+        verifyBatchedModifications(batchedModifications.get(1), new MergeModification(mergePath1, mergeNode1),
+                new MergeModification(mergePath2, mergeNode2), new WriteModification(writePath3, writeNode3));
+
+        verifyBatchedModifications(batchedModifications.get(2), new MergeModification(mergePath3, mergeNode3),
+                new DeleteModification(deletePath2));
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class, BatchedModificationsReply.class, BatchedModificationsReply.class);
+    }
+
+    @Test
+    public void testModificationOperationBatchingWithInterleavedReads() throws Throwable {
+        int shardBatchedModificationCount = 10;
+        doReturn(dataStoreContextBuilder.shardBatchedModificationCount(shardBatchedModificationCount).build()).
+                when(mockActorContext).getDatastoreContext();
+
+        ActorRef actorRef = setupActorContextWithInitialCreateTransaction(getSystem(), READ_WRITE);
+
+        expectBatchedModifications(actorRef, shardBatchedModificationCount);
+
+        YangInstanceIdentifier writePath1 = TestModel.TEST_PATH;
+        NormalizedNode<?, ?> writeNode1 = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        YangInstanceIdentifier writePath2 = TestModel.OUTER_LIST_PATH;
+        NormalizedNode<?, ?> writeNode2 = ImmutableNodes.containerNode(TestModel.OUTER_LIST_QNAME);
+
+        YangInstanceIdentifier mergePath1 = TestModel.TEST_PATH;
+        NormalizedNode<?, ?> mergeNode1 = ImmutableNodes.containerNode(TestModel.TEST_QNAME);
+
+        YangInstanceIdentifier mergePath2 = TestModel.INNER_LIST_PATH;
+        NormalizedNode<?, ?> mergeNode2 = ImmutableNodes.containerNode(TestModel.INNER_LIST_QNAME);
+
+        YangInstanceIdentifier deletePath = TestModel.OUTER_LIST_PATH;
+
+        doReturn(readSerializedDataReply(writeNode2)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData(writePath2));
+
+        doReturn(readSerializedDataReply(mergeNode2)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData(mergePath2));
+
+        doReturn(dataExistsSerializedReply(true)).when(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        TransactionProxy transactionProxy = new TransactionProxy(mockActorContext, READ_WRITE);
+
+        transactionProxy.write(writePath1, writeNode1);
+        transactionProxy.write(writePath2, writeNode2);
+
+        Optional<NormalizedNode<?, ?>> readOptional = transactionProxy.read(writePath2).
+                get(5, TimeUnit.SECONDS);
+
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+        assertEquals("Response NormalizedNode", writeNode2, readOptional.get());
+
+        transactionProxy.merge(mergePath1, mergeNode1);
+        transactionProxy.merge(mergePath2, mergeNode2);
+
+        readOptional = transactionProxy.read(mergePath2).get(5, TimeUnit.SECONDS);
+
+        transactionProxy.delete(deletePath);
+
+        Boolean exists = transactionProxy.exists(TestModel.TEST_PATH).checkedGet();
+        assertEquals("Exists response", true, exists);
+
+        assertEquals("NormalizedNode isPresent", true, readOptional.isPresent());
+        assertEquals("Response NormalizedNode", mergeNode2, readOptional.get());
+
+        List<BatchedModifications> batchedModifications = captureBatchedModifications(actorRef);
+        assertEquals("Captured BatchedModifications count", 3, batchedModifications.size());
+
+        verifyBatchedModifications(batchedModifications.get(0), new WriteModification(writePath1, writeNode1),
+                new WriteModification(writePath2, writeNode2));
+
+        verifyBatchedModifications(batchedModifications.get(1), new MergeModification(mergePath1, mergeNode1),
+                new MergeModification(mergePath2, mergeNode2));
+
+        verifyBatchedModifications(batchedModifications.get(2), new DeleteModification(deletePath));
+
+        InOrder inOrder = Mockito.inOrder(mockActorContext);
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData(writePath2));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedReadData(mergePath2));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), isA(BatchedModifications.class));
+
+        inOrder.verify(mockActorContext).executeOperationAsync(
+                eq(actorSelection(actorRef)), eqSerializedDataExists());
+
+        verifyRecordingOperationFutures(transactionProxy.getRecordedOperationFutures(),
+                BatchedModificationsReply.class, BatchedModificationsReply.class, BatchedModificationsReply.class);
+    }
+
+    private List<BatchedModifications> captureBatchedModifications(ActorRef actorRef) {
+        ArgumentCaptor<BatchedModifications> batchedModificationsCaptor =
+                ArgumentCaptor.forClass(BatchedModifications.class);
+        verify(mockActorContext, Mockito.atLeastOnce()).executeOperationAsync(
+                eq(actorSelection(actorRef)), batchedModificationsCaptor.capture());
+
+        List<BatchedModifications> batchedModifications = filterCaptured(
+                batchedModificationsCaptor, BatchedModifications.class);
+        return batchedModifications;
+    }
+
+    private <T> List<T> filterCaptured(ArgumentCaptor<T> captor, Class<T> type) {
+        List<T> captured = new ArrayList<>();
+        for(T c: captor.getAllValues()) {
+            if(type.isInstance(c)) {
+                captured.add(c);
+            }
+        }
+
+        return captured;
+    }
+
+    private void verifyOneBatchedModification(ActorRef actorRef, Modification expected) {
+        List<BatchedModifications> batchedModifications = captureBatchedModifications(actorRef);
+        assertEquals("Captured BatchedModifications count", 1, batchedModifications.size());
+
+        verifyBatchedModifications(batchedModifications.get(0), expected);
+    }
+
+    private void verifyBatchedModifications(Object message, Modification... expected) {
+        assertEquals("Message type", BatchedModifications.class, message.getClass());
+        BatchedModifications batchedModifications = (BatchedModifications)message;
+        assertEquals("BatchedModifications size", expected.length, batchedModifications.getModifications().size());
+        for(int i = 0; i < batchedModifications.getModifications().size(); i++) {
+            Modification actual = batchedModifications.getModifications().get(i);
+            assertEquals("Modification type", expected[i].getClass(), actual.getClass());
+            assertEquals("getPath", ((AbstractModification)expected[i]).getPath(),
+                    ((AbstractModification)actual).getPath());
+            if(actual instanceof WriteModification) {
+                assertEquals("getData", ((WriteModification)expected[i]).getData(),
+                        ((WriteModification)actual).getData());
+            }
+        }
     }
 }