This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Caching of database Connections is normally handled via a central Conection Pooling mechanism. The pool opens all the required connections and you request connections from the pool and not directly from the database. I hope I understood your question correctly. This assumes that the application is acting as a client to a database server, and the application itself may be a server to the next tier. Dave