Class loading
Class loaders are part of the JVM code and are responsible for finding and loading class files. Class loaders enable applications deployed on servers to access repositories of available classes and resources. Application developers and deployers must consider the location of class and resource files, and the class loaders used to access those files, to make the files available to deployed applications. Class loaders affect the packaging of applications and the runtime behavior of packaged applications of deployed applications.
This topic describes how to configure class loaders for application files or modules installed on an application server.
To better understand class loaders in WebSphere Application Server, read Class loaders. The topic Class loading: Resources for learning refers to additional sources.
Configure class loaders for application files or modules installed on an application server using the administrative console. We configure class loaders to ensure that deployed application files and modules can access the classes and resources that they need to run successfully.
Tasks
- If an installed application module uses a resource, create a resource provider that specifies the directory name of the resource drivers.
Do not specify the resource JAR file names. All JAR files in the specified directory are added into the class path of the WAS extensions class loader. If a resource driver requires a native library (.dll or .so file), specify the name of the directory containing the library in the native path of the resource configuration.
- Specify class-loader values for an application server.
- Specify class-loader values for an installed enterprise application.
- Specify the class-loader mode for an installed web module.
- If our deployed application uses shared library files, associate the shared library files with the application. Use a library reference to associate a shared library file with the application.
- If we have not done so already, define shared libraries for library files that the applications need.
- Define a library reference for each shared library that the application uses.
What to do next
After configuring class loaders, ensure that the application performs as desired. To diagnose and fix problems with class loaders, refer to Troubleshooting class loaders.
Subtopics
- Class loaders
- Configure class loaders of a server
- Class loader collection
- Class loader settings
- Configure application class loaders
- Configure web module class loaders
- Class loading: Resources for learning
Create shared libraries Associating shared libraries with applications or modules Troubleshoot class loaders Assemble applications Manage shared libraries Class loader settings Enterprise application settings Web module deployment settings Java EE client application class loading