Class loading
Class loaders are part of the JVM code and are responsible for finding and loading class files. Class loaders enable applications that are 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 that are installed on an appserver.
To better understand class loaders in WAS, read Class loaders. The topic Class loading: Resources for learning refers to additional sources.
Overview
Configure class loaders for application files or modules that are installed on an appserver using the console. You configure class loaders to ensure that deployed application files and modules can access the classes and resources that they need to run successfully.
Procedure
- 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 Java archive (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 that contains the library in the native path of the resource configuration.
- Specify class-loader values for an appserver.
- Specify class-loader values for an installed enterprise application.
- Specify the class-loader mode for an installed Web module.
- If your deployed application uses shared library files, associate the shared library files with your application. Use a library reference to associate a shared library file with your application.
- If you have not done so already, define a shared library instance for each library file that your applications need.
- Define a library reference instance for each shared library that your application uses.
What to do next
After configuring class loaders, ensure that your application performs as desired. To diagnose and fix problems with class loaders, refer to Troubleshooting class loaders.
Class loaders
Configure class loaders of a server
Class loader collection
Configure application class loaders
Configure Web module class loaders
Class loading: Resources for learning
Related concepts
J2EE application client class loading
Jakarta Commons Logging
Related tasks
Assembling applications
Manage shared libraries
Configure applications to use Jakarta Commons Logging
Troubleshooting class loaders
Related Reference
Enterprise application settings
Web module deployment settings