WebSphere Class Loaders and Shared Library, Part 3 (Class loader in WebSphre Por

Class loader in WebSphere Portal

WebSphere Portal Express classloading follows the WebSphere Application Server hierarchy for classpaths and search orders. A particular classloader can reference other classes as long as the other classes can be loaded by the same classloader or any of its ancestors, but not its children. The graphic illustrates where WebSphere Portal Express and portlet applications fit into the classloading hierarchy.

As illustrated, WebSphere Portal Express is an application extension under WebSphere Application Server. Consequently, the WebSphere Portal Express core classes are in the classpath portal_server_root /shared/app . If an installed portlet application includes a classloader, the portlet application classloader is an application classloader under WebSphere Portal Express.

Shared Library

Shared libraries are files used by multiple applications. Shared libraries are files used by multiple applications.

Shared Library Level

You can define a shared library at the cell, node, or server level.

Shared Library Class Loader

·        When shared libraries are associated with an server

A separate class loader is used. This class loader is the parent of the application class loader, and the WebSphere Application Server extensions class loader is its parent

·        When shared libraries are associated with an application

Shared libraries are loaded by the application class loader

Associate Shared Library

·        Using the WAS admin console to associate libraries with application or server

·        By declaring the dependent library .jar file in the MANIFEST.MF file of the application.

To be continued...

Resources:

Shared Libraries : WAS6 InfoCenter (Setting up the application serving environment->Administrating application servers-> Managing shared libraries)

Class Loaders : WAS6 InfoCenter (Developing and deploying applications->Class loading)

Classloading in WebSphere Portal : WebSphere Portal InfoCenter (Developing portlets->Portlet development basics->Creating a simple portlet)

Best Practice for Using Common Application Files

Learning more about the Classloader