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.
The contextpath is necessary for identifying the application (but can be omitted if the app is the root application), and profile can be a servlet mapping that invokes a servlet that will look up the user's profile and forward to a JSp for displaying it.
Within the servlet, the username part of the URL can be retrieved using the path info methods on the request.