How to keep track of the number of active user in a Channel API chat

I'm working on a small chat using the google Channel API and appengine. Is there an easy way to know how many users are active on the chat?

Thanks, David

Solution

If you're asking to track how many clients are connected to a given channel, the answer should be easy: 1. The Channel API doesn't support broadcast.

If you're asking for how to track whether a client is connected to a channel, there's not a built-in way to do that right now. You can see the answer to this question for more info: AppEngine Channel API - Best way to check if a channel is still open (server side)

Presence for the Channel API (referenced in the above question) is coming very, very soon.