ejbasynccallback.java

本文介绍了一种EJB异步调用方法,使得客户端能够方便地异步调用EJB

/**
 * javax.ejb.async - Proposed Classes/Interfaces for EJB Async support
 *
 * @version     1.1
 * @author      Andrzej Jan Taramina, Chaeron Consulting Corporation
 */
	
package javax.ejb.async;

//***************************************************************************
//*
//*		Imports
//*
//***************************************************************************/

//***************************************************************************
//*
//*		EJBAsyncCallback Interface definition
//*
//***************************************************************************/

/**
 * The <code>EJBAsyncCallback</code> interface should be implemented by any class
 * that will be used to receive and process a callback resulting from the completion
 * of an EJB asynchronous operation.
 * <p>
 * A remote method invocation on an EJB Bean (Session or Entity) will be processed
 * asynchronously if and only if one of the parameters passed to the method invocation
 * is of type EJBAsyncCallback.  It is proposed that the last parameter in the list would
 * be the EJBAsyncCallback, except in the situation where a client context object is being
 * passed in by the user, in which case the callback is the second last parameter and the
 * context object would be the last parameter.
 * <p>
 * When an EJB Async remote method invocation has completed, the asyncMethodCompleted()
 * method will be called in the specified EJBAsyncCallback object by the EJB Server 
 * (more specifically  by the client EJBObject stub) and will be passed an EJBAsyncResponse
 * object that contains the return value of the remote method invocation or an exception.
 * <p>
 * For example, if you have an Entity bean called myBean whose interface is defined as follows:
 * <p><pre><blockquote>
 * public interface myBean extends EJBObject
 * {
 * 		public void doSomething( String parmValue ) throws RemoteException;
 *		public void doSomething( String parmValue, EJBAsyncCallback cb ) throws RemoteException;
 * }
 * </blockquote></pre>
 * If you issue the first doSomething() method, the invocation will be normal (Synchronous), however
 * if you issue the second doSomething() method, specifying an EJBAsyncCallback object for the second
 * parameter, then the invocation will be asynchronous.  If you specify the second form of the call
 * and pass in a null callback object, then the call will also be synchronous and equivalent to the first
 * method.
 * <p>
 *	Optionally you can also include a client context object that will be returned to you in the
 * EJBAsyncResult object passed to the EJBAsyncCallback.  The client context object can be any
 * Java Object that the user wishes to get access to in the EJBAsyncCallback and could be used to
 * identify the method invocation or other contextual information about the specific method
 * invocation as follows:
 * <p><pre><blockquote>
 * public interface myBean extends EJBObject
 * {
 * 		public void doSomething( String parmValue, EJBAsyncCallback cb, Object clientContext ) throws RemoteException;
 * }
 * </blockquote></pre>
 * 
 * @see	   javax.ejb.async.EJBAsyncResult
 *
 * @author  Andrzej Jan Taramina, Chaeron Consulting Corporation
 * @version 1.1, 03/17/99
 */
 
public interface EJBAsyncCallback
{
	
	//***************************************************************************
	//*
	//*		EJBAsyncCallback method signatures
	//*
	//***************************************************************************/
		
	/**
	* When an EJB Async remote method invocation has completed, the asyncMethodCompleted()
 	* method will be called.
	*
	* @param   result An EJBAsyncResult object containing the return value of the
 	*					remote method invocation or an exception.
	*/
	
	public void asyncMethodCompleted( EJBAsyncResult result );
	
}