X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-dom-api%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fmd%2Fsal%2Fdom%2Fapi%2FDOMDataReadTransaction.java;h=111a503890f9e14fe8d3c8a1d70c3d739f5621d0;hb=751776589ce049c9c1c611d06335599b92087ee6;hp=fc251c8445a77d1485a2dffc4880afa9b3907f95;hpb=8e42b08cb626a60919c145b2a46d94114c3905d6;p=controller.git

diff --git a/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataReadTransaction.java b/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataReadTransaction.java
index fc251c8445..111a503890 100644
--- a/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataReadTransaction.java
+++ b/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataReadTransaction.java
@@ -7,17 +7,17 @@
  */
 package org.opendaylight.controller.md.sal.dom.api;
 
+import com.google.common.base.Optional;
+import com.google.common.util.concurrent.CheckedFuture;
 import org.opendaylight.controller.md.sal.common.api.data.AsyncReadTransaction;
 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 
-import com.google.common.base.Optional;
-import com.google.common.util.concurrent.CheckedFuture;
-
 /**
  * A transaction that provides read access to a logical data store.
+ *
  * <p>
  * For more information on usage and examples, please see the documentation in {@link AsyncReadTransaction}.
  */
@@ -25,7 +25,8 @@ public interface DOMDataReadTransaction extends AsyncReadTransaction<YangInstanc
 
     /**
      * Reads data from provided logical data store located at the provided path.
-     *<p>
+     *
+     * <p>
      * If the target is a subtree, then the whole subtree is read (and will be
      * accessible from the returned data object).
      *
@@ -47,4 +48,29 @@ public interface DOMDataReadTransaction extends AsyncReadTransaction<YangInstanc
      */
     CheckedFuture<Optional<NormalizedNode<?,?>>, ReadFailedException> read(
             LogicalDatastoreType store, YangInstanceIdentifier path);
+
+    /**
+     /**
+     * Checks if data is available in the logical data store located at provided path.
+     *
+     * <p>
+     * Note: a successful result from this method makes no guarantee that a subsequent call to {@link #read}
+     * will succeed. It is possible that the data resides in a data store on a remote node and, if that
+     * node goes down or a network failure occurs, a subsequent read would fail. Another scenario is if
+     * the data is deleted in between the calls to <code>exists</code> and <code>read</code>
+     *
+     * @param store
+     *            Logical data store from which read should occur.
+     * @param path
+     *            Path which uniquely identifies subtree which client want to
+     *            check existence of
+     * @return a CheckFuture containing the result of the check.
+     *         <ul>
+     *         <li>If the data at the supplied path exists, the Future returns a Boolean
+     *         whose value is true, false otherwise</li>
+     *         <li>If checking for the data fails, the Future will fail with a
+     *         {@link ReadFailedException} or an exception derived from ReadFailedException.</li>
+     *         </ul>
+     */
+    CheckedFuture<Boolean, ReadFailedException> exists(LogicalDatastoreType store, YangInstanceIdentifier path);
 }