Managing shared libraries

Shared libraries are files used by multiple applications. Each shared library consists of a symbolic name, a Java class path, and a native path for loading Java Native Interface (JNI) libraries. You can use shared libraries to reduce the number of duplicate library files on your system.

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Your applications use the same library files. The applications already are deployed on a server or you currently are deploying the applications.

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Suppose that you have four applications that use the same library file, my_sample.jar. Instead of having four copies of my_sample.jar on your system after the four applications are deployed, you can define a shared library for my_sample.jar and have the four deployed applications use that one my_sample.jar library file.

Isolated shared libraries provide another way to reduce the number of library files. Isolated shared libraries each have their own class loader, enabling a single instance of the classes to be shared across the applications. Each application can specify which isolated shared libraries that it wants to reference. Different applications can reference different versions of the isolated shared library, resulting in a set of applications sharing an isolated shared library. With isolated shared libraries, some applications can share a single copy of Library A, Version 1 while other applications share a single copy of Library A, Version 2, for a total of two instances in memory.

Using the administrative console, you can define shared libraries for the library files that multiple applications use and then associate the libraries with specific applications or modules or with an application server. Guidelines for associating shared libraries are as follows:

Instead of using the administrative console to associate a shared library with an application, you can use an installed optional package. You associate a shared library to an application by declaring the dependent library .jar file in the MANIFEST.MF file of the application. Refer to the Java 2 Platform, Enterprise Edition (J2EE) 1.4 specification, section 8.2 for an example.

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Last updatedLast updated: Feb 5, 2014 9:49:51 PM CST
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