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 <h1 class="topictitle1">EJB 2.x development resources</h1>


 <div><p>This topic describes resources and development tools that are commonly
 used in EJB version 2.x development.</p>

 <dl>
 <dt class="dlterm"><strong>EJB modules</strong></dt>

 <dd> <p>EJB modules are displayed in the Project Explorer view of the Java™ EE
 perspective, and they correspond to EJB projects.</p>
 <p>An EJB module is used
 to assemble one or more enterprise beans into a single deployable unit. An
 EJB module is developed in an EJB project, and it can either be exported as
 a standalone EJB JAR file, or combined with other EJB or Web modules within
 an enterprise application. An EJB JAR file uses the format of a standard Java archive
 file. An EJB module contains the following: </p>
 <ul>
 <li>One or more enterprise beans and their associated .class and .java files.</li>

 <li>Graphics and other files depending on the need of the enterprise bean. </li>

 <li>A deployment descriptor. The file type for the deployment descriptor is
 Extensible Markup Language (XML). This file declares the contents of the EJB
 module, defines the structure of the beans in the module, and provides a description
 of how the beans are to be used at run time. </li>

 <li>A MANIFEST.MF file in the <span class="uicontrol">META-INF</span> directory. The
 manifest file can contain a class path entry, with references to other JAR
 files or EJB modules in a J2EE enterprise application. It defines the module's
 external dependencies.</li>

 </ul>
 <p>An EJB module is installed and runs in an EJB container.</p>
 <p>An
 enterprise bean is a Java component that can be combined with
 other resources to create distributed client/server applications.</p>
 <div class="note"><span class="notetitle">Note:</span> If
 you choose to create an EJB client JAR file for your EJB module, the client
 interface classes for the enterprise beans will not be included in the EJB
 JAR file, but are included in the EJB client JAR file.</div>
 </dd>


 <dt class="dlterm"><strong>EJB projects</strong></dt>

 <dd> <p>In the workbench, you create and maintain resources for enterprise
 applications in projects. An EJB project is a logical module that allows you
 to organize your enterprise beans.</p>
 <p>The workbench supports EJB 1.1, EJB
 2.0, and EJB 2.1 projects. The J2EE specification level of a containing EAR
 project must be set to J2EE 1.3 or higher for EJB 2.0 projects, and J2EE 1.4
 for EJB 2.1 projects. In an EJB 1.1 project, you will only be able to create
 EJB 1.1 beans.</p>
 <p>An EJB project is a specialized Java project.
 Like a Java project, an EJB project must have one or more source
 folders to contain the source and output files for the project. By default,
 the source folder is named <strong>ejbModule</strong>, but you can change that name
 when you create the project or new source folders. When you publish or deploy
 the project, the contents of the folder or folders are aggregated. </p>
 <p>You
 cannot use the EJB project as the source folder, doing so will cause errors.
 Also, though you can have more than one source folder in the project, only
 one of these source folders can contain the <span class="uicontrol">META-INF</span> folder
 in which the MANIFEST.MF and deployment descriptor files reside.</p>
 <div class="note"><span class="notetitle">Note:</span> If
 you choose to create an EJB client JAR file for your EJB module, the client
 interface classes for the enterprise beans will not be included in the EJB
 project, but in separate EJB client JAR project. EJB client JAR projects are
 displayed in the Project Explorer as Java projects under the <strong>Other Projects</strong> node.</div>
 </dd>


 <dt class="dlterm"><strong>EJB client projects</strong></dt>

 <dd> <p>The EJB tooling supports the creation of EJB client JAR projects for
 EJB modules. An EJB client JAR project contains all the interface classes
 that a client program needs to use the client views of the enterprise beans
 that are contained in the EJB project. When you create an EJB client project
 for an EJB project, a new Java project is created and added to your
 workspace. The EJB client project is added as a project utility JAR file to
 each module that the EJB project belongs to.</p>
 <p>By default, when you use
 the wizard to create an EJB project, an EJB client JAR project is also created.
 However, you can clear this option in the wizard.</p>
 <div class="tip"><span class="tiptitle">Tip:</span> You
 can also add the EJB client project to another enterprise application that
 does not include the EJB project as a module. This will ensure that the EJB
 client JAR file is exported and packaged with the EAR file when the application
 is exported.</div>
 </dd>


 <dt class="dlterm"><strong>Enterprise beans</strong></dt>

 <dd> <p>An enterprise bean is a Java component that can be combined with
 other resources to create distributed client/server applications.</p>
 <p>There
 are three types of enterprise beans: entity beans, session beans, and message-driven
 beans. Typically, all types of beans are used together within an enterprise
 application.</p>
 <dl>
 <dt class="dlterm"><strong>Entity beans</strong></dt>

 <dd>Entity beans store permanent data. Entity beans with container-managed
 persistence (CMP) require database connections. Entity beans with bean-managed
 persistence manage permanent data in whichever manner is defined in the bean
 code. This can include writing to databases or XML files, for example.</dd>


 <dt class="dlterm"><strong>Session beans</strong></dt>

 <dd>Session beans do not require database access, though they can obtain it
 indirectly (as needed) by accessing entity beans. Session beans can also obtain
 direct access to databases (and other resources) through the use of resource
 references.</dd>


 <dt class="dlterm"><strong>Message-driven beans</strong></dt>

 <dd>Message-driven beans are a special kind of enterprise bean that act as
 message consumers in the JMS messaging system. As with standard JMS message
 consumers, message-driven beans perform business logic based on the message
 contents. In several ways, the dynamic creation and allocation of message-driven
 bean instances mimics the behavior of stateless session enterprise beans.
 However, message-driven beans are different from stateless session enterprise
 beans (and other types of enterprise beans) in a couple of ways:<ul>
 <li>Message-driven beans process multiple JMS messages asynchronously, rather
 than processing a serialized sequence of method calls.</li>

 <li>Message-driven beans have no home or remote interface, and therefore cannot
 be directly accessed by internal or external clients.</li>

 </ul>
 </dd>

 </dl>
 </dd>


 <dt class="dlterm"><strong>Deployment descriptors</strong></dt>

 <dd> <p>A deployment descriptor contains configuration data that the runtime
 environment uses for an application. A deployment descriptor can include information
 about the following: </p>
 <ul>
 <li>The structure and content (enterprise beans, for example) of the application.</li>

 <li>References to internal and external dependencies. For example, an enterprise
 bean in an EJB module can require another enterprise bean that is not bundled
 in the same module.</li>

 <li>References to resource factory objects, such as URLs or JDBC data sources.</li>

 <li>Security roles that the container uses when implementing the required
 access control for the application.</li>

 <li>Transactional information about how (and whether) the container is to
 manage transactions for the application.</li>

 </ul>
 <p>Deployment descriptors are XML files packaged with the application's
 files in a Java archive file. An EJB deployment descriptor is called
 ejb-jar.xml and is located in the <strong>META-INF</strong> folder of an EJB project.
 A J2EE application contains one application-level deployment descriptor file,
 governing the application as a whole. It also contains several component-level
 deployment descriptors, one for each module in the application.</p>
 </dd>

 </dl>

 </div>

 <div>
 <ul class="ullinks">
 <li class="ulchildlink"><strong><a href="../topics/tecrtpro.html">Creating EJB projects</a></strong><br />
 An EJB project is used to organize the resources contained in an EJB module.</li>
 <li class="ulchildlink"><strong><a href="../topics/ceclientjars.html">EJB 2.x client JAR projects</a></strong><br />
 An EJB client JAR project contains all the class files that a client program needs to use the client view of the enterprise beans that are contained in the EJB module.</li>
 <li class="ulchildlink"><strong><a href="../topics/teimp.html">Importing EJB 2.x JAR files</a></strong><br />
 You can import beans and other metadata from an EJB JAR file into a new or existing EJB project.</li>
 <li class="ulchildlink"><strong><a href="../topics/teexp.html">Exporting EJB 2.x projects to EJB JAR files</a></strong><br />
 After you have tested your enterprise beans, you can export the module into an EJB JAR file.</li>
 </ul>

 <div class="familylinks">
 <div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/ceover.html" title="The workbench provides a specialized environment that you can use to develop and test enterprise beans that conform to the distributed component architecture defined in the Sun Microsystems Enterprise JavaBeans (EJB) version specification. This product supports the Enterprise JavaBeans 1.1, 2.0, 2.1, and 3.0 specification levels.">EJB 2.x application development</a></div>
 </div>
 </div>

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	<title>EJB 2.x development resources</title>
	</head>
	<body id="ceresrc"><a name="ceresrc"><!-- --></a>


	<h1 class="topictitle1">EJB 2.x development resources</h1>



	<div><p>This topic describes resources and development tools that are commonly
	used in EJB version 2.x development.</p>

	<dl>
	<dt class="dlterm"><strong>EJB modules</strong></dt>

	<dd> <p>EJB modules are displayed in the Project Explorer view of the Java™ EE
	perspective, and they correspond to EJB projects.</p>
	<p>An EJB module is used
	to assemble one or more enterprise beans into a single deployable unit. An
	EJB module is developed in an EJB project, and it can either be exported as
	a standalone EJB JAR file, or combined with other EJB or Web modules within
	an enterprise application. An EJB JAR file uses the format of a standard Java archive
	file. An EJB module contains the following: </p>
	<ul>
	<li>One or more enterprise beans and their associated .class and .java files.</li>

	<li>Graphics and other files depending on the need of the enterprise bean. </li>

	<li>A deployment descriptor. The file type for the deployment descriptor is
	Extensible Markup Language (XML). This file declares the contents of the EJB
	module, defines the structure of the beans in the module, and provides a description
	of how the beans are to be used at run time. </li>

	<li>A MANIFEST.MF file in the <span class="uicontrol">META-INF</span> directory. The
	manifest file can contain a class path entry, with references to other JAR
	files or EJB modules in a J2EE enterprise application. It defines the module's
	external dependencies.</li>

	</ul>
	<p>An EJB module is installed and runs in an EJB container.</p>
	<p>An
	enterprise bean is a Java component that can be combined with
	other resources to create distributed client/server applications.</p>
	<div class="note"><span class="notetitle">Note:</span> If
	you choose to create an EJB client JAR file for your EJB module, the client
	interface classes for the enterprise beans will not be included in the EJB
	JAR file, but are included in the EJB client JAR file.</div>
	</dd>


	<dt class="dlterm"><strong>EJB projects</strong></dt>

	<dd> <p>In the workbench, you create and maintain resources for enterprise
	applications in projects. An EJB project is a logical module that allows you
	to organize your enterprise beans.</p>
	<p>The workbench supports EJB 1.1, EJB
	2.0, and EJB 2.1 projects. The J2EE specification level of a containing EAR
	project must be set to J2EE 1.3 or higher for EJB 2.0 projects, and J2EE 1.4
	for EJB 2.1 projects. In an EJB 1.1 project, you will only be able to create
	EJB 1.1 beans.</p>
	<p>An EJB project is a specialized Java project.
	Like a Java project, an EJB project must have one or more source
	folders to contain the source and output files for the project. By default,
	the source folder is named <strong>ejbModule</strong>, but you can change that name
	when you create the project or new source folders. When you publish or deploy
	the project, the contents of the folder or folders are aggregated. </p>
	<p>You
	cannot use the EJB project as the source folder, doing so will cause errors.
	Also, though you can have more than one source folder in the project, only
	one of these source folders can contain the <span class="uicontrol">META-INF</span> folder
	in which the MANIFEST.MF and deployment descriptor files reside.</p>
	<div class="note"><span class="notetitle">Note:</span> If
	you choose to create an EJB client JAR file for your EJB module, the client
	interface classes for the enterprise beans will not be included in the EJB
	project, but in separate EJB client JAR project. EJB client JAR projects are
	displayed in the Project Explorer as Java projects under the <strong>Other Projects</strong> node.</div>
	</dd>


	<dt class="dlterm"><strong>EJB client projects</strong></dt>

	<dd> <p>The EJB tooling supports the creation of EJB client JAR projects for
	EJB modules. An EJB client JAR project contains all the interface classes
	that a client program needs to use the client views of the enterprise beans
	that are contained in the EJB project. When you create an EJB client project
	for an EJB project, a new Java project is created and added to your
	workspace. The EJB client project is added as a project utility JAR file to
	each module that the EJB project belongs to.</p>
	<p>By default, when you use
	the wizard to create an EJB project, an EJB client JAR project is also created.
	However, you can clear this option in the wizard.</p>
	<div class="tip"><span class="tiptitle">Tip:</span> You
	can also add the EJB client project to another enterprise application that
	does not include the EJB project as a module. This will ensure that the EJB
	client JAR file is exported and packaged with the EAR file when the application
	is exported.</div>
	</dd>


	<dt class="dlterm"><strong>Enterprise beans</strong></dt>

	<dd> <p>An enterprise bean is a Java component that can be combined with
	other resources to create distributed client/server applications.</p>
	<p>There
	are three types of enterprise beans: entity beans, session beans, and message-driven
	beans. Typically, all types of beans are used together within an enterprise
	application.</p>
	<dl>
	<dt class="dlterm"><strong>Entity beans</strong></dt>

	<dd>Entity beans store permanent data. Entity beans with container-managed
	persistence (CMP) require database connections. Entity beans with bean-managed
	persistence manage permanent data in whichever manner is defined in the bean
	code. This can include writing to databases or XML files, for example.</dd>


	<dt class="dlterm"><strong>Session beans</strong></dt>

	<dd>Session beans do not require database access, though they can obtain it
	indirectly (as needed) by accessing entity beans. Session beans can also obtain
	direct access to databases (and other resources) through the use of resource
	references.</dd>


	<dt class="dlterm"><strong>Message-driven beans</strong></dt>

	<dd>Message-driven beans are a special kind of enterprise bean that act as
	message consumers in the JMS messaging system. As with standard JMS message
	consumers, message-driven beans perform business logic based on the message
	contents. In several ways, the dynamic creation and allocation of message-driven
	bean instances mimics the behavior of stateless session enterprise beans.
	However, message-driven beans are different from stateless session enterprise
	beans (and other types of enterprise beans) in a couple of ways:<ul>
	<li>Message-driven beans process multiple JMS messages asynchronously, rather
	than processing a serialized sequence of method calls.</li>

	<li>Message-driven beans have no home or remote interface, and therefore cannot
	be directly accessed by internal or external clients.</li>

	</ul>
	</dd>

	</dl>
	</dd>


	<dt class="dlterm"><strong>Deployment descriptors</strong></dt>

	<dd> <p>A deployment descriptor contains configuration data that the runtime
	environment uses for an application. A deployment descriptor can include information
	about the following: </p>
	<ul>
	<li>The structure and content (enterprise beans, for example) of the application.</li>

	<li>References to internal and external dependencies. For example, an enterprise
	bean in an EJB module can require another enterprise bean that is not bundled
	in the same module.</li>

	<li>References to resource factory objects, such as URLs or JDBC data sources.</li>

	<li>Security roles that the container uses when implementing the required
	access control for the application.</li>

	<li>Transactional information about how (and whether) the container is to
	manage transactions for the application.</li>

	</ul>
	<p>Deployment descriptors are XML files packaged with the application's
	files in a Java archive file. An EJB deployment descriptor is called
	ejb-jar.xml and is located in the <strong>META-INF</strong> folder of an EJB project.
	A J2EE application contains one application-level deployment descriptor file,
	governing the application as a whole. It also contains several component-level
	deployment descriptors, one for each module in the application.</p>
	</dd>

	</dl>

	</div>

	<div>
	<ul class="ullinks">
	<li class="ulchildlink"><strong><a href="../topics/tecrtpro.html">Creating EJB projects</a></strong><br />
	An EJB project is used to organize the resources contained in an EJB module.</li>
	<li class="ulchildlink"><strong><a href="../topics/ceclientjars.html">EJB 2.x client JAR projects</a></strong><br />
	An EJB client JAR project contains all the class files that a client program needs to use the client view of the enterprise beans that are contained in the EJB module.</li>
	<li class="ulchildlink"><strong><a href="../topics/teimp.html">Importing EJB 2.x JAR files</a></strong><br />
	You can import beans and other metadata from an EJB JAR file into a new or existing EJB project.</li>
	<li class="ulchildlink"><strong><a href="../topics/teexp.html">Exporting EJB 2.x projects to EJB JAR files</a></strong><br />
	After you have tested your enterprise beans, you can export the module into an EJB JAR file.</li>
	</ul>

	<div class="familylinks">
	<div class="parentlink"><strong>Parent topic:</strong> <a href="../topics/ceover.html" title="The workbench provides a specialized environment that you can use to develop and test enterprise beans that conform to the distributed component architecture defined in the Sun Microsystems Enterprise JavaBeans (EJB) version specification. This product supports the Enterprise JavaBeans 1.1, 2.0, 2.1, and 3.0 specification levels.">EJB 2.x application development</a></div>
	</div>
	</div>

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