How I can use web.xml to point to the Tomcat JDBC?

Question

I am just wondering whether somehow I can use web.xml to point to the Tomcat JDBC Realm that I am using. Are those two completely disjoint or I can link them together.

Answer 1

They are disjoint.

web.xml is for the developer who has (almost) no knowledge of the context (environment) in which his application will run.

context.xml (or equivalents) is the tool for the administrator to provide that knowledge to the application.