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 <h1 class="topictitle1">Session Beans</h1>


 <div><p />

 <p>A <strong>session bean</strong> is a type of enterprise bean. It is created by a
 client and usually exists only for the duration of a single client-server
 session.</p>

 <p>Session beans are useful for describing interactions between other beans
 (taskflow) and for implementing particular tasks. They do not represent data
 in the database, but they can access data, so we can use session beans to
 read, update, and insert data in a business process. Session beans access
 data that spans concepts, is not shared, and is usually read-only. Session
 beans contain business logic, and entities model persistent data. There are
 three types of session beans: stateless, stateful and singleton. </p>

 <ul>
 <li><strong>Stateless session beans</strong> <p>A stateless session bean is pooled by
 the container to handle multiple requests from multiple clients and does not
 maintain any conversational state.</p>
  </li>

 <li> <strong>Stateful session beans</strong> <p>A stateful session bean acts on behalf
 of a single client and maintains client-specific session information (called
 conversational state) across multiple method calls and transactions. It exists
 for the duration of a single client/server session.</p>
  </li>

 <li> <strong>Singleton session beans</strong> <p>A Singleton session bean is a session
 bean component that is instantiated once per application. In cases where the container
 is distributed over many virtual machines, each application will have one bean instance
 of the Singleton for each JVM.</p>
  </li>

 </ul>

 </div>

 <div>
 <div class="familylinks">
 <div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/sessbwiz.html" title="You can use a wizard to create a session bean and add it to your project.">Creating EJB Session Beans</a></div>
 </div>
 </div>

 </body>
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	<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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	<meta name="copyright" content="Copyright (c) 2000, 2008 IBM Corporation and others. All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at https://www.eclipse.org/legal/epl-2.0/. Contributors: IBM Corporation - initial API and implementation" />
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	<title>Session Beans</title>
	</head>
	<body id="sessb"><a name="sessb"><!-- --></a>


	<h1 class="topictitle1">Session Beans</h1>



	<div><p />

	<p>A <strong>session bean</strong> is a type of enterprise bean. It is created by a
	client and usually exists only for the duration of a single client-server
	session.</p>

	<p>Session beans are useful for describing interactions between other beans
	(taskflow) and for implementing particular tasks. They do not represent data
	in the database, but they can access data, so we can use session beans to
	read, update, and insert data in a business process. Session beans access
	data that spans concepts, is not shared, and is usually read-only. Session
	beans contain business logic, and entities model persistent data. There are
	three types of session beans: stateless, stateful and singleton. </p>

	<ul>
	<li><strong>Stateless session beans</strong> <p>A stateless session bean is pooled by
	the container to handle multiple requests from multiple clients and does not
	maintain any conversational state.</p>
	</li>

	<li> <strong>Stateful session beans</strong> <p>A stateful session bean acts on behalf
	of a single client and maintains client-specific session information (called
	conversational state) across multiple method calls and transactions. It exists
	for the duration of a single client/server session.</p>
	</li>

	<li> <strong>Singleton session beans</strong> <p>A Singleton session bean is a session
	bean component that is instantiated once per application. In cases where the container
	is distributed over many virtual machines, each application will have one bean instance
	of the Singleton for each JVM.</p>
	</li>

	</ul>

	</div>

	<div>
	<div class="familylinks">
	<div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/sessbwiz.html" title="You can use a wizard to create a session bean and add it to your project.">Creating EJB Session Beans</a></div>
	</div>
	</div>

	</body>
	</html>