Use installed optional packages

 

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Overview

You can associate one or more shared libraries with an application using an installed optional package that declares the shared libraries in the application's manifest file. Classes represented by the shared libraries are then loaded in the application's class loader, making the classes available to the application.

Read about installed optional packages in Installed optional packages and in section 8.2 of the J2EE specification, V1.4.

WAS does not support the J2SE Installed Optional Package semantics, which primarily serve the applet environment. WAS ignores applet-specific tags within manifest files.

Installed optional packages expand the existing shared library capabilities of an appserver. Prior to V6, an administrator was required to associate a shared library to an application or server. Installed optional packages enable an administrator to declare a dependency in an application's manifest file to a shared library, with installed optional package elements listed in the manifest file, and automatically associate the application to the shared library. During application installation, the shared library .jar file is added to the class path of the application class loader.

If you use an installed optional package to associate a shared library with an application, do not associate the same shared library with an application class loader or a server class loader using the console.

 

Procedure

  1. Assemble the library file, including the manifest information that identifies it as an extension. Two sample manifest files follow. The first sample manifest file has application app1.ear refer to a single shared library file util.jar: 

     app1.ear:
    META-INF/application.xml
    ejb1.jar:
         META-INF/MANIFEST.MF:
             Extension-List: util
             util-Extension-Name: com/example/util
             util-Specification-Version: 1.4
         META-INF/ejb-jar.xml



    util.jar:
    META-INF/MANIFEST.MF:
        Extension-Name: com/example/util
        Specification-Title: example.com's util package
        Specification-Version: 1.4
        Specification-Vendor: example.com
        Implementation-Version: build96
    The second sample manifest file has application app1.ear refer to multiple shared library .jar files: 

    app1.ear:
    META-INF/application.xml
    ejb1.jar:
         META-INF/MANIFEST.MF:
             Extension-List: util1 util2 util3
             Util1-Extension-Name: com/example/util1
             Util1-Specification-Version: 1.4
             Util2-Extension-Name: com/example/util2
             Util2-Specification-Version: 1.4
             Util3-Extension-Name: com/example/util3
             Util3-Specification-Version: 1.4
         META-INF/ejb-jar.xml



    util1.jar:
    META-INF/MANIFEST.MF:
        Extension-Name: com/example/util1
        Specification-Title: example.com's util package
        Specification-Version: 1.4
        Specification-Vendor: example.com
        Implementation-Version: build96



    util2.jar:
    META-INF/MANIFEST.MF:
        Extension-Name: com/example/util2
        Specification-Title: example.com's util package
        Specification-Version: 1.4
        Specification-Vendor: example.com
        Implementation-Version: build96



    util3.jar:
    META-INF/MANIFEST.MF:
        Extension-Name: com/example/util3
        Specification-Title: example.com's util package
        Specification-Version: 1.4
        Specification-Vendor: example.com
        Implementation-Version: build96

  2. Create a shared library that represents the library file assembled in step 1. This installs the library file as a WAS shared library.

  3. Copy the shared library .jar file to the cluster members.

  4. Assemble the application, declaring in the application manifest file dependencies to the library files named the manifest created for step 1.

  5. Install the application on the server or cluster.

 

Results

During application installation, the shared library .jar files are added to the class path of the application class loader.


Class loaders

 

Related tasks

Manage shared libraries