How to get context of another war in tomcat

Lets say you have two web applications that run in the same tomcat server.
And for some weird reason you want to call code of the other war.


You can write something like this in your servlet/jsp to get the context of the other war:

javax.servlet.ServletContext context = application.getContext("otherWarName");

Now, when you have context to the war, you can access the objects under it. In example, you can include the other jsp in your request:

javax.servlet.RequestDispatcher rd = context.getRequestDispatcher("other.jsp");
rd.include(request, response);

Looks simple? Well, it is. It even works on jboss, but it does not in tomcat: application.getContext("otherWarName") returns null, so you'll get the NullPointerException.

The missing part is configured in the conf/server.xml. You'll need to define cross context for the applications that you want to be accessible from the other applications. Under the host element add:

<context path="/otherWarName" debug="0" reloadable="true" crosscontext="true"></context>

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Recommended Reading

1. Professional Apache Tomcat 6 (WROX Professional Guides)
2. Tomcat 6 Developer's Guide
3. Pro Apache Tomcat 6

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