I really need some expert help here!. Does anybody knows of a way of getting the list of the users currently connected to a BlazeDS server? Is there any built-in mechanism of knowing this? or do I have to implement some kind of server side logic every time a user access my Flex application and store all logged in users details somewhere and retrieve them later?
The nearest thing I can think of, using BlazeDS, is to obtain a list of clients currently subscribed to a destination, but this won't solve the problem IMO.
First of all, you need to define a destination and make sure that all clients will actually subscribe to it (see BlazeDS documentation for this). Then, on the server, you can then get a reference to the message service
MessageService messageService;
messageService = (MessageService) messageBroker.getService("message-service");
and ask for all subscribers with the getSubscribersIds method on the MessageService instance, specifying the name of your destination. This will only returns a number of identifiers, internally generated by BlazeDS (they are also available on the client side of the connection).
To resolve the same problem, I used this approach in combination to a custom server-side logic to store logged-in users (explicitly invoked login/logout methods). Regularly looking at the subscribers can help to clean this store, because in my experience there's no way to be sure that a "logout" method will always successfully called, expecially from Flex client running in the browser, while BlazeDS will automatically take care of cleanup of the subscribers.
I don't like very much this approach, probably someone came up with a better solution..