The way I do it now is tell the client to check back in X seconds depending on how many available workers compared to used workers there are. I already have th

The way I do it now is tell the client to check back in X seconds depending on how many available workers compared to used workers there are. I already have this wrapper for client side on iOS and working on a Batman.js version. I usually do this for client side Login with different providers. Say Facebook or Twitter. Login on the client, obtain token, send to server for validation. Server validates against Facebook/Twitter. Server will tell the client to check back in X seconds. Client waits X seconds and does another check. Server is either done or not. I rather do that, than to keep a request open. It's easier to manage on iOS as well since, say the user decides to check their email while the login is still processing.