diff --git a/hadoop-common/CHANGES.txt b/hadoop-common/CHANGES.txt
index c499c750f0..5435ea6814 100644
--- a/hadoop-common/CHANGES.txt
+++ b/hadoop-common/CHANGES.txt
@@ -63,6 +63,8 @@ Trunk (unreleased changes)
HADOOP-6385. dfs should support -rmdir (was HDFS-639). (Daryn Sharp
via mattf)
+ HADOOP-7455. HA: Introduce HA Service Protocol Interface. (suresh)
+
IMPROVEMENTS
HADOOP-7042. Updates to test-patch.sh to include failed test names and
diff --git a/hadoop-common/src/main/java/org/apache/hadoop/ha/HAServiceProtocol.java b/hadoop-common/src/main/java/org/apache/hadoop/ha/HAServiceProtocol.java
new file mode 100644
index 0000000000..20f0d04bc2
--- /dev/null
+++ b/hadoop-common/src/main/java/org/apache/hadoop/ha/HAServiceProtocol.java
@@ -0,0 +1,72 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.ha;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.ipc.VersionedProtocol;
+
+/**
+ * Protocol interface that provides High Availability related primitives to
+ * monitor and fail-over the service.
+ *
+ * This interface could be used by HA frameworks to manage the service.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public interface HAServiceProtocol extends VersionedProtocol {
+ /**
+ * Initial version of the protocol
+ */
+ public static final long versionID = 1L;
+
+ /**
+ * Monitor the health of service. This periodically called by the HA
+ * frameworks to monitor the health of the service.
+ *
+ * Service is expected to perform checks to ensure it is functional.
+ * If the service is not healthy due to failure or partial failure,
+ * it is expected to throw {@link HealthCheckFailedException}.
+ * The definition of service not healthy is left to the service.
+ *
+ * Note that when health check of an Active service fails,
+ * failover to standby may be done.
+ *
+ * @throws HealthCheckFailedException
+ * if the health check of a service fails.
+ */
+ public void monitorHealth() throws HealthCheckFailedException;
+
+ /**
+ * Request service to transition to active state. No operation, if the
+ * service is already in active state.
+ *
+ * @throws ServiceFailedException
+ * if transition from standby to active fails.
+ */
+ public void transitionToActive() throws ServiceFailedException;
+
+ /**
+ * Request service to transition to standby state. No operation, if the
+ * service is already in standby state.
+ *
+ * @throws ServiceFailedException
+ * if transition from active to standby fails.
+ */
+ public void transitionToStandby() throws ServiceFailedException;
+}
diff --git a/hadoop-common/src/main/java/org/apache/hadoop/ha/HealthCheckFailedException.java b/hadoop-common/src/main/java/org/apache/hadoop/ha/HealthCheckFailedException.java
new file mode 100644
index 0000000000..a73e4ef3c2
--- /dev/null
+++ b/hadoop-common/src/main/java/org/apache/hadoop/ha/HealthCheckFailedException.java
@@ -0,0 +1,55 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.ha;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Exception thrown to indicate that health check of a service
+ * failed.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public class HealthCheckFailedException extends Exception {
+ private static final long serialVersionUID = 1L;
+
+ /**
+ * Constructs exception with the specified detail message.
+ * @param message the detail message (which is saved for later retrieval
+ * by the {@link #getMessage()} method).
+ */
+ public HealthCheckFailedException(final String message) {
+ super(message);
+ }
+
+ /**
+ * Constructs a new exception with the specified detail message and
+ * cause.
+ *
+ * @param message the detail message (which is saved for later retrieval
+ * by the {@link #getMessage()} method).
+ * @param cause the cause (which is saved for later retrieval by the
+ * {@link #getCause()} method). (A null value is
+ * permitted, and indicates that the cause is nonexistent or
+ * unknown.)
+ */
+ public HealthCheckFailedException(String message, Throwable cause) {
+ super(message, cause);
+ }
+}
diff --git a/hadoop-common/src/main/java/org/apache/hadoop/ha/ServiceFailedException.java b/hadoop-common/src/main/java/org/apache/hadoop/ha/ServiceFailedException.java
new file mode 100644
index 0000000000..e0f8cfc837
--- /dev/null
+++ b/hadoop-common/src/main/java/org/apache/hadoop/ha/ServiceFailedException.java
@@ -0,0 +1,56 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.ha;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+
+/**
+ * Exception thrown to indicate that an operation performed
+ * to modify the state of a service or application failed.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public class ServiceFailedException extends Exception {
+ private static final long serialVersionUID = 1L;
+
+ /**
+ * Constructs exception with the specified detail message.
+ * @param message the detail message (which is saved for later retrieval
+ * by the {@link #getMessage()} method).
+ */
+ public ServiceFailedException(final String message) {
+ super(message);
+ }
+
+ /**
+ * Constructs a new exception with the specified detail message and
+ * cause.
+ *
+ * @param message the detail message (which is saved for later retrieval
+ * by the {@link #getMessage()} method).
+ * @param cause the cause (which is saved for later retrieval by the
+ * {@link #getCause()} method). (A null value is
+ * permitted, and indicates that the cause is nonexistent or
+ * unknown.)
+ */
+ public ServiceFailedException(String message, Throwable cause) {
+ super(message, cause);
+ }
+}