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Develop applications that use the Asynchronous Invocation API

We can use the Asynchronous Invocation API to transfer events that require processing in the context of a Session Initiation Protocol (SIP) application session to any server in a cluster based on the related application session ID. The Asynchronous Invocation API transfers the event task to the correct server.

Read the API documentation for information on the following asynchronous work classes:

For more information about the API classes, see the Reference section in the information center and click APIs - Application Programming Interfaces to view a list of the product API specifications. When running code outside of a SIP thread, application developers can use the Asynchronous Invocation API to create an object, and configure the server to run that object either on a different thread in the same container, or on a different server, if that is where the session exists.

The following example shows the class structure for the AsynchronousWork class, which is the abstract base class that is extended when using the API. 

 public abstract class AsynchronousWork implements Serializable
 {
 private String sessionId;
 public AsynchronousWork(String sessionId)
 {
 this.sessionId = sessionId;
 ....
 }
 public void dispatch (AsynchronousWorkListener listener)
 {
 ....
 }
 public abstract Serializable doAsyncTask();
 }

  1. Extend the abstract class AsynchronousWork with the SIP related code. The extended implementation of the doAsyncTask() method is invoked on the target server containing the SipApplicationSession, and whose ID was set in the constructor that implements the AsynchronousWork class. The implementation class must pass the session ID to the base class by calling super in the constructor. 
    public class MyClass extends AsynchronousWork
{
String _sessionId;

public MyClass(String sessionId) {
super(sessionId);
_sessionId = sessionId;}

// This code is invoked on the target machine or thread public Serializable doAsyncTask() {
// Application code goes here; for instance:
appSession = sessionUtils.getApplicationSession(_sessionId);
appSession.createRequest().....

Serializable myResponse = new MyResponse();
myResponse.setStatus(200);
return (myResponse);}}
  2. To receive information about the task completion, implement the AsynchronousWorkListener class, as in the following example. The code in these methods are invoked on the source server. 
    public class MyListener implements AsynchronousWorkListener
{
public void workCompleted(Serializeable myResponse)
{
....}
public void workFailed(int reasonCode, String reason)
{}}
  3. To invoke the asynchronous call; for example, when we receive the proprietary message, use this sample code as an example. 
    public void onMyMessage()
{
// Obtain the session ID from the message or // somewhere else
String sessionId = obtainIdFromMessage();

// Create the runnable
MyClass myClass = new MyClass(sessionId);

// Create the listener MyListener myListener = new MyListener();

// Dispatch it myClass.dispatch(myListener);}


Results

The SIP container ensures the task is invoked in the correct server and on the correct thread, so the application can avoid synchronization on the session level.


Subtopics


Related concepts:

Asynchronous Invocation API


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