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.ListenableFuture;
+import com.google.common.util.concurrent.CheckedFuture;
/**
* A transaction that provides read access to a logical data store.
* @param path
* Path which uniquely identifies subtree which client want to
* read
- * @return Listenable Future which contains read result
+ * @return a CheckFuture containing the result of the read. The Future blocks until the
+ * commit operation is complete. Once complete:
* <ul>
- * <li>If data at supplied path exists the
- * {@link ListeblaFuture#get()} returns Optional object containing
- * data once read is done.
- * <li>If data at supplied path does not exists the
- * {@link ListenbleFuture#get()} returns {@link Optional#absent()}.
+ * <li>If the data at the supplied path exists, the Future returns an Optional object
+ * containing the data.</li>
+ * <li>If the data at the supplied path does not exist, the Future returns
+ * Optional#absent().</li>
+ * <li>If the read of the data fails, the Future will fail with a
+ * {@link ReadFailedException} or an exception derived from ReadFailedException.</li>
* </ul>
*/
- ListenableFuture<Optional<NormalizedNode<?,?>>> read(LogicalDatastoreType store,YangInstanceIdentifier path);
+ 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);
+
}