When do you use "Allowed" as a SessionMode in WCF?

Question

Can you give me a scenario when you would use "Allowed" as the SessionMode value in a WCF service contract?

Answer 1

When you want to support both bindings which support sessions (e.g., a rich client) and those who don't (e.g. a browser-based client). If there is a session, you simply use the session, and if there's not, you'd either use a non-session-dependent codepath, or you'd use another mechanism to store the session information (such as HTTP cookies, for example).