Is long polling possible with a Rails application using EventMachine?

Question

I'm writing a simple chat room application in Rails 3.1 - for learning purposes. For starters I have all the needed models (messages, users, rooms, etc.) and things work great. The clients poll the server every minute (for example) and get new messages if they have any.

I would like to change the simple polling to long polling and can't figure out if this can be done in the same app or do I have to create some other Push server for the long polling.

I read a lot about EventMachine and changed my rails app to user it as I wanted to use EventMachine for the event driven mechanics. I thought that the EventMachine channel would come in handy for this. A client would connect and wait for a message in the chat room and it will receive a message only when one was sent to the room.

What I can't figure out is how can I share the EventMachine::Channel instance between all my client connections. Is this approach even possible or am I going at it the wrong way?

If possible I would like a solution that can run as a single rails application hosted on Heroku.

Answer 1

Yeah sure. I just wrote a demo using event machine. My case is that player walking around a map, and other players should be able to see it. The demo looks like that:

1. A client establishes a connection, reporting its own coordinate(generated randomly)

2. There is an array preserving all the coordinates for each client

3. When a client moves, it sends its new coordinate to the server. Then the server finds out people near him(from the array), and push the new coordinate to those clients.

I tested it with nearly 5000 clients, and each second 20-30 players moves its position. And the server process only takes less that 100M memory & 50%-60% cpu usage(on a single core).

In your case, I think you should probably try faye too. It's based on event machine, and an appropriate solution to things like chat room.