package org.opendaylight.mdsal.binding.api;
import org.opendaylight.mdsal.common.api.AsyncReadOnlyTransaction;
-
+import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
+import org.opendaylight.mdsal.common.api.ReadFailedException;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import com.google.common.base.Optional;
+import com.google.common.util.concurrent.CheckedFuture;
+
/**
* A transaction that provides a stateful read-only view of the data tree.
* <p>
* For more information on usage and examples, please see the documentation in
* {@link org.opendaylight.mdsal.common.api.AsyncReadTransaction}.
*/
-public interface ReadOnlyTransaction extends ReadTransaction, AsyncReadOnlyTransaction<InstanceIdentifier<?>, DataObject> {
+public interface ReadOnlyTransaction extends AsyncReadOnlyTransaction<InstanceIdentifier<?>, DataObject> {
+ /**
+ * Reads data from the provided logical data store located at the provided path.
+ *<p>
+ * If the target is a subtree, then the whole subtree is read (and will be
+ * accessible from the returned data object).
+ *
+ * @param store
+ * Logical data store from which read should occur.
+ * @param path
+ * Path which uniquely identifies subtree which client want to
+ * read
+ * @return a CheckFuture containing the result of the read. The Future blocks until the
+ * commit operation is complete. Once complete:
+ * <ul>
+ * <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>
+ */
+ <T extends DataObject> CheckedFuture<Optional<T>,ReadFailedException> read(
+ LogicalDatastoreType store, InstanceIdentifier<T> path);
}