Web application authentication design pattern

I'm working on a web application and I'm having problem accessing the database on server side because there is no user for the DB proxy to map. In other word, I have a method which will start as soon as the application comes online and will call itself every 5 seconds to check for new messages. If it receives a specified message, it then goes to the database and finds whatever it needs. However, accessing database on server side wouldn't be possible because there is no user for the DB proxy to map. So what is a good design pattern for this type of application? Should I need an application account for these type of automation process?

Btw, I'm using Weblogic JPA 2.1 for database stuff.

Thanks in advance.