Session management in GWT without using Java on the server?

Question

I am using GWT for my client side application. I am not using GWT/Java for the server. However, I am not sure how I can handle session management. The GWT application resides on one page, all server calls are done via AJAX. If a session expires on the server... let's assume the user didn't close the browser, but left the application open, how could my server notify the application that the session has expired and that the client side portion should show the login screen again?

What is meant by client side session management? That seems inherently insecure.

I'm not looking for code. I'm looking for ideas, techniques, potential solutions etc. I've considered Comet http://en.wikipedia.org/wiki/Comet_(programming), but that doesn't seem like that will work very well without using Java on the server side. Maybe, I'm wrong? I don't want to poll the server either.

Any thoughts or insight?

Answer 1

What should happen if the session expired on the server-side, then the next time the client sends a request to the server, it will either create a new session, or, more likely, send back a message to the client that it is trying to access a page without a session, and send them to the login screen. However, you will still need to wait until the client sends a message to the server.

Answer 2

Without knowing how you're doing your RPC is working, its hard to give good advice.

If your AJAX service requires a user to be authenticated (IE have a valid session), it is ok to just send a 401 error saying that the user is invalid. Client-side can interpret the 401 error as a message that it should set the user up for re-authentication.

Answer 3

We handled this in our application, by detecting when the server sent back a redirect to the login screen (it would come through the response to the Ajax call), and popped up a dialog asking the user for their password again, but pre-filled their username. We then posted that to the same place the login page does, as if it was the login page, and so the user was logged into this new session automatically. Finally we just re-submitted the ajax call again, so it was a seamless process to the user (eg: they didn't have to click the action again).

Since we stored all the state on the client, and not in session variables we didn't have any problems trying to persist data across sessions.