jQuery Ajax calls to web service seem to be synchronous

Question

I have two ajax calls to a web service from jquery.

The first call (GetMessages) starts an interval in javascript (setInterval) and return

Answer 1

This is because you have enable the Session and the Session lock all the calls until they return.

You can read also this question: Replacing ASP.Net's session entirely

also read: https://stackoverflow.com/a/3660837/159270