[HADOOP-3969] Provide Mechanism to optionally expose public org.apache.hadoop.util.Services APIs

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Incomplete
• Assignee: Unassigned
• Reporter: Pete Wyckoff
• Created: 19/Aug/08 00:33
• Updated: 18/Jul/14 20:58
• Resolved: 18/Jul/14 20:58

Description

Enhance manageability of Hadoop Services by providing Jute, Thrift, REST, ... APIs to select methods in the Service class (or potentially others).
This will allow external tools written in a myriad of languages to query the state of Hadoop Servers and/or interact with them.

This can be encapsulated in the Service class by defining a very simple interface and then optionally instantiating such an implementation provided in the Configuration.

Some methods to be implemented include all the public methods in Service:

ping()
isRunning()
terminate()
getServiceState()
verifyServiceState()
isTerminated(),

INTERFACE:

package org.apache.hadoop.util;

public interface ExposeServiceAPIs {

   /**
   * @param service - the service whose APIs are to be exposed
  * @param  serviceName - a symbolic name for the service
  * @param configuration - the hadoop configuration object
 **/
  public void initialize(Service service, String serviceName, Configuration conf) throws IOException,
  public boolean start();
  public boolean stop();
} ;

Two straightforward implementations of this would be:

1. Servlet that exposes the APIs via REST
2. Thrift DDL of the service APIs and an implementation in Java + bindings in C++, Java, Perl, Python, Ruby, PHP

Issue Links

• depends upon: HDFS-326 Add a lifecycle interface for Hadoop components: namenodes, job clients, etc.