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6.3: Assembling applications and generating deployment code >
6.3.2: Setting properties for a module
6.3.2: Setting properties for a module
A module's properties are used to create a deployment descriptor for
the module. The properties represent the deployment descriptor elements
as defined in the J2EE specifications. The Application Assembly tool
automatically creates deployment descriptor files based on values entered in
the property dialog boxes and wizards. The deployment descriptor is an
XML document that contains application configuration data that the run-time
uses. In general, a deployment descriptor contains the following
information:
- Information about the content of the module being assembled. For
example, for an EJB module, the deployment descriptor lists each enterprise
bean's class, home interface class, remote interface class, whether the
bean is an entity or session bean, and the bean's attributes (such as
persistence management type and primary key class for entity beans).
- References to a module's internal and external dependencies (such as
enterprise beans, databases, and resource connection factories needed by the
module). Internal dependencies are dependencies on other components
within the same module. External dependencies are dependencies on
components residing outside of the module. For example, an enterprise
bean in an EJB module can require another enterprise bean that is not packaged
in the same module. The deployment descriptor can contain references to
the remote bean's home interface. The deployment descriptor can
also include JNDI binding information that the container uses to locate the
remote bean at install time.
- Run-time-specific information needed by the application. For
example, the servlet mappings needed for a Web application or the persistence
management (BMP or CMP) to be used by an entity bean.
- References to security roles. Security information is used when the
module is deployed.
In addition to XML files, the Application Assembly Tool automatically
generates XMI files to store binding and IBM extension information.
Binding information maps a resource (enterprise bean or resource connection
factory object) from the logical name specified in the deployment descriptor
to its actual name in the global JNDI namespace. IBM deployment
descriptor extensions are additions to the standard descriptors for J2EE
applications, Web applications, and enterprise beans. The extensions
allow you to specify properties that enable Enterprise Edition or legacy
(older) systems to work in the WebSphere Application Server
environment. For example, an extension property is used to define how
to manage transaction scoping for an enterprise bean's methods.
A J2EE application contains one application-level deployment descriptor
file, governing the application as a whole. It also contains a
component-level deployment descriptor file, one governing each module in the
application. For example, the application-level deployment descriptor
specifies security information for the application and defines how often the
application is to be reloaded. The component-level deployment
descriptor (for example, for an EJB module) specifies the following:
- General properties of the EJB module, such as the location of class files
needed for a client program to access the enterprise beans in the module and
the icons to be associated with the module.
- The deployable enterprise beans that the module will contain.
- Security roles used to access resources in the module.
- Transaction attributes for the enterprise bean methods.
- A default datasource to be used by entity beans in the module, if one is
not specified.
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