docs/org.eclipse.jst.ejb.doc.user/topics/cejb3vejb21.html - jeetools/webtools.javaee - Git at Google

 <?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">
 <html lang="en-us" xml:lang="en-us">
 <head>
 <meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
 <meta name="copyright" content="Copyright (c) 2000, 2011 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" />
 <meta name="DC.rights.owner" content="(C) Copyright 2000, 2011" />
 <meta content="public" name="security" />
 <meta content="index,follow" name="Robots" />
 <meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
 <meta content="concept" name="DC.Type" />
 <meta name="DC.Title" content="Differences between EJB 3.0 and EJB 2.1" />
 <meta name="abstract" content="Compared to EJB 2.1, EJB 3.0 simplifies the process of creating Enterprise JavaBean applications." />
 <meta name="description" content="Compared to EJB 2.1, EJB 3.0 simplifies the process of creating Enterprise JavaBean applications." />
 <meta content="Enterprise JavaBeans 3.0" name="DC.subject" />
 <meta content="Enterprise JavaBeans 3.0" name="keywords" />
 <meta scheme="URI" name="DC.Relation" content="../topics/ejbarch.html" />
 <meta content="XHTML" name="DC.Format" />
 <meta content="compareejb2" name="DC.Identifier" />
 <meta content="en-us" name="DC.Language" />
 <link href="../../org.eclipse.wst.doc.user/common.css" type="text/css" rel="stylesheet" />
 <title>Enterprise JavaBean version differences between EJB 3.0 and EJB
 2.1</title>
 </head>
 <body id="compareejb2"><a name="compareejb2"><!-- --></a>


 <h1 class="topictitle1">Differences between EJB 3.0 and EJB 2.1</h1>


 <div><p>Compared to EJB 2.1, EJB 3.0 simplifies the process of creating
 Enterprise JavaBean applications.</p>

 <p>The underlying concept of the EJB 3.0 specification centers on a plain
 old Java™ object
 (POJO) programming model that uses Java annotations to capture information
 that deployment descriptors used to contain.  Deployment descriptors are now
 optional in most cases.  Using default values liberally also means that you
 need to write and maintain less supporting code. This greatly simplifies the
 programming experience in creating and using EJB 3.0 components.</p>

 <p>While EJB 2.1 added support for Web services, changes in the implementation
 of session beans, changes in how enterprise beans are invoked and a new XML
 schema to replace the DTD that defined ejb-jar.xml deployment descriptor,
 EJB 3.0 has taken this one step further. EJB 3.0 has introduced a lightweight
 entity bean persistence mechanism through the Java Persistence API. These entities are
 POJO based and can then be run outside of an EJB container and do not require
 any interfaces or EJB code in them. Similarly, session beans also no longer
 require EJB-specific component interfaces either.</p>

 <p><strong>Comparison of EJB 2.1 class plus Deployment Descriptor file with equivalent
 EJB 3.0 class</strong></p>

 <p>The examples in Table 1 are functionally equivalent:</p>


 <div class="tablenoborder"><table summary="" cellspacing="0" cellpadding="4" frame="border" border="1" rules="all"><caption>Table 1. Comparison of EJB 2.1 and EJB 3.0</caption>
 <thead align="left">
 <tr valign="bottom">
 <th valign="bottom" id="N100A4">EJB 2.1 </th>

 <th valign="bottom" id="N100AB">EJB 3.0</th>

 </tr>

 </thead>

 <tbody>
 <tr>
 <td valign="top" headers="N100A4 "><p><strong>Java Class</strong></p>
 <pre>public class AccountBean
 implements javax.ejb.SessionBean {

      SessionContext ctx;
      DataSource accountDB;

      public void setSessionContext(SessionContext ctx) {
         this.ctx = ctx;
      }

      public void ejbCreate() {
           accountDB = (DataSource)ctx.lookup(
                           "jdbc/accountDB");

      }
      public void ejbActivate() { }
      public void ejbPassivate() { }
      public void ejbRemove() { }

      public void setAccountDeposit(int empId,
                                       double deposit) {
        ...
        Connection conn = accountDB.getConnection();
        ...
      }
   ...
 }</pre>
 </td>

 <td valign="top" headers="N100AB "><p><strong>Java Class</strong></p>
 <pre>@Stateless
 public class AccountBean implements Account
 {
      @Resource private DataSource accountDB;

      public void setAccountDeposit(int customerId,
                                       double deposit) {
        ...
        Connection conn = accountDB.getConnection();
        ...
      }
   ...
 }</pre>
 </td>

 </tr>

 <tr>
 <td valign="top" headers="N100A4 "><p><strong>Deployment Descriptor</strong></p>
 <pre>&lt;session&gt;
   &lt;ejb-name&gt;AccountBean&lt;/ejb-name&gt;
   &lt;local-home&gt;AccountHome&lt;/local-home&gt;
   &lt;local&gt;Account&lt;/local&gt;
   &lt;ejb-class&gt;com.example.AccountBean&lt;/ejb-class&gt;
   &lt;session-type&gt;Stateless&lt;/session-type&gt;
   &lt;transaction-type&gt;Container&lt;/transaction-type&gt;
   &lt;resource-ref&gt;
     &lt;res-ref-name&gt;jdbc/accountDB&lt;/res-ref-name&gt;
     &lt;res-ref-type&gt;javax.sql.DataSource&lt;/res-ref-type&gt;
     &lt;res-auth&gt;Container&lt;/res-auth&gt;
   &lt;/resource-ref&gt;
 &lt;/session&gt;
 ...
 &lt;assembly-descriptor&gt;...&lt;/assembly-descriptor&gt;
 </pre>
 </td>

 <td valign="top" headers="N100AB ">&nbsp;</td>

 </tr>

 </tbody>

 </table>
 </div>

 <div class="p">The following four facets of Java EE 5 contributed the most to the changes
 in EJB 3.0 from EJB 2.1:<ul>
 <li>Plain old Java objects</li>

 <li>Annotations</li>

 <li>Implied values</li>

 <li>Persistence</li>

 </ul>
 </div>

 </div>

 <div>
 <div class="familylinks">
 <div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/ejbarch.html" title="This topic provides a high-level overview of the distributed component architecture defined in the Sun Microsystems Enterprise JavaBeans (EJB) version 3.0 architecture specification.">EJB 3.0 and EJB 3.1 architecture</a></div>
 </div>
 </div>

 </body>
 </html>
	<?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">
	<html lang="en-us" xml:lang="en-us">
	<head>
	<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
	<meta name="copyright" content="Copyright (c) 2000, 2011 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" />
	<meta name="DC.rights.owner" content="(C) Copyright 2000, 2011" />
	<meta content="public" name="security" />
	<meta content="index,follow" name="Robots" />
	<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
	<meta content="concept" name="DC.Type" />
	<meta name="DC.Title" content="Differences between EJB 3.0 and EJB 2.1" />
	<meta name="abstract" content="Compared to EJB 2.1, EJB 3.0 simplifies the process of creating Enterprise JavaBean applications." />
	<meta name="description" content="Compared to EJB 2.1, EJB 3.0 simplifies the process of creating Enterprise JavaBean applications." />
	<meta content="Enterprise JavaBeans 3.0" name="DC.subject" />
	<meta content="Enterprise JavaBeans 3.0" name="keywords" />
	<meta scheme="URI" name="DC.Relation" content="../topics/ejbarch.html" />
	<meta content="XHTML" name="DC.Format" />
	<meta content="compareejb2" name="DC.Identifier" />
	<meta content="en-us" name="DC.Language" />
	<link href="../../org.eclipse.wst.doc.user/common.css" type="text/css" rel="stylesheet" />
	<title>Enterprise JavaBean version differences between EJB 3.0 and EJB
	2.1</title>
	</head>
	<body id="compareejb2"><a name="compareejb2"><!-- --></a>


	<h1 class="topictitle1">Differences between EJB 3.0 and EJB 2.1</h1>




	<div><p>Compared to EJB 2.1, EJB 3.0 simplifies the process of creating
	Enterprise JavaBean applications.</p>

	<p>The underlying concept of the EJB 3.0 specification centers on a plain
	old Java™ object
	(POJO) programming model that uses Java annotations to capture information
	that deployment descriptors used to contain. Deployment descriptors are now
	optional in most cases. Using default values liberally also means that you
	need to write and maintain less supporting code. This greatly simplifies the
	programming experience in creating and using EJB 3.0 components.</p>

	<p>While EJB 2.1 added support for Web services, changes in the implementation
	of session beans, changes in how enterprise beans are invoked and a new XML
	schema to replace the DTD that defined ejb-jar.xml deployment descriptor,
	EJB 3.0 has taken this one step further. EJB 3.0 has introduced a lightweight
	entity bean persistence mechanism through the Java Persistence API. These entities are
	POJO based and can then be run outside of an EJB container and do not require
	any interfaces or EJB code in them. Similarly, session beans also no longer
	require EJB-specific component interfaces either.</p>

	<p><strong>Comparison of EJB 2.1 class plus Deployment Descriptor file with equivalent
	EJB 3.0 class</strong></p>

	<p>The examples in Table 1 are functionally equivalent:</p>


	<div class="tablenoborder"><table summary="" cellspacing="0" cellpadding="4" frame="border" border="1" rules="all"><caption>Table 1. Comparison of EJB 2.1 and EJB 3.0</caption>
	<thead align="left">
	<tr valign="bottom">
	<th valign="bottom" id="N100A4">EJB 2.1 </th>

	<th valign="bottom" id="N100AB">EJB 3.0</th>

	</tr>

	</thead>

	<tbody>
	<tr>
	<td valign="top" headers="N100A4 "><p><strong>Java Class</strong></p>
	<pre>public class AccountBean
	implements javax.ejb.SessionBean {

	SessionContext ctx;
	DataSource accountDB;

	public void setSessionContext(SessionContext ctx) {
	this.ctx = ctx;
	}

	public void ejbCreate() {
	accountDB = (DataSource)ctx.lookup(
	"jdbc/accountDB");

	}
	public void ejbActivate() { }
	public void ejbPassivate() { }
	public void ejbRemove() { }

	public void setAccountDeposit(int empId,
	double deposit) {
	...
	Connection conn = accountDB.getConnection();
	...
	}
	...
	}</pre>
	</td>

	<td valign="top" headers="N100AB "><p><strong>Java Class</strong></p>
	<pre>@Stateless
	public class AccountBean implements Account
	{
	@Resource private DataSource accountDB;

	public void setAccountDeposit(int customerId,
	double deposit) {
	...
	Connection conn = accountDB.getConnection();
	...
	}
	...
	}</pre>
	</td>

	</tr>

	<tr>
	<td valign="top" headers="N100A4 "><p><strong>Deployment Descriptor</strong></p>
	<pre><session>
	<ejb-name>AccountBean</ejb-name>
	<local-home>AccountHome</local-home>
	<local>Account</local>
	<ejb-class>com.example.AccountBean</ejb-class>
	<session-type>Stateless</session-type>
	<transaction-type>Container</transaction-type>
	<resource-ref>
	<res-ref-name>jdbc/accountDB</res-ref-name>
	<res-ref-type>javax.sql.DataSource</res-ref-type>
	<res-auth>Container</res-auth>
	</resource-ref>
	</session>
	...
	<assembly-descriptor>...</assembly-descriptor>
	</pre>
	</td>

	<td valign="top" headers="N100AB "> </td>

	</tr>

	</tbody>

	</table>
	</div>

	<div class="p">The following four facets of Java EE 5 contributed the most to the changes
	in EJB 3.0 from EJB 2.1:<ul>
	<li>Plain old Java objects</li>

	<li>Annotations</li>

	<li>Implied values</li>

	<li>Persistence</li>

	</ul>
	</div>

	</div>

	<div>
	<div class="familylinks">
	<div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/ejbarch.html" title="This topic provides a high-level overview of the distributed component architecture defined in the Sun Microsystems Enterprise JavaBeans (EJB) version 3.0 architecture specification.">EJB 3.0 and EJB 3.1 architecture</a></div>
	</div>
	</div>

	</body>
	</html>