Optional datasources in java web applications
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I'm creating a java web application which should run on multiple application servers (jetty, tomcat, websphere, jboss). There is an optional datasource in this application. If it is configured the application will use it, otherwise some functionality in the application will be disabled.

The problem is, if I define the resource-ref in the web.xml, it will be required to be defined in the application context. If I don't define it in the web.xml, then when I try to deploy the application in websphere, there is no way to reference the datasource in the application. 

Is there a way to make websphere aware of the optional datasource without always having to define it in the application context?
