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JRE System Library vs Server Runtime


I am curious about the differences between the JRE System Library and the Server Runtime. I am using Eclipse. I can see that both of these are added to the build path and that they are both pointed at the same location.

JRE System Library [WebSphere Application Server V8.5 JRE]
WebSphere Application Server v8.5 [WebSphere Application Server v8.5]

When I expand these libraries, I see none of the same JAR's. And I can see that the first entry is loading most if it's JAR's from C:\Program Files\IBM\WebSphere\AppServer\java\jre\lib. I can see that the second is loading most if it's JAR's from C:\Program Files\IBM\WebSphere\AppServer\plugins.

At first glance I would have assumed they would both be loading the same JAR's. What is the purpose of each of these libraries, and why are they loading different JAR's?


Solution

  • the JRE System Library contains the basic classes, contained in rt.jar, the package java.lang., java.util., etc.

    and the Server Runtime contains the classes required for the Java EE framework, Servlets, JMS, etc