My purpose is to implement a mutliuser shared whiteboard for my university project. Such a type of application needs to communicate extensively with the server, so AJAX is not fast enough.
The possibilities which I have found on the web were:
This small article is going to be about comparing the performance of Channel API and Node.js+socket.io
Using the code
I am not going to explain how the code is working, as it's pretty much explained in the Resources which I have used (see below).
If you would like to run the Google app engine implementation you would have to use the Google app engine (see their documentation here: https://developers.google.com/appengine/docs/python/gettingstartedpython27/)
If you would like to run the node.js+socket.io implementation, you would need to use some hosting for it. I used free amazon's hosting for that (here is the explanation on how to configure your amazon instance for using node.js http://iconof.com/blog/how-to-install-setup-node-js-on-amazon-aws-ec2-complete-guide/)
The source code is attached to the article in zip archives.
So, the code which I wrote for the Python+Channel API (hosted on google app engine) is almost the same as the one which I wrote for Node.js+socket.io (hosten on Amazon micro instance), but performance of socket.io is better than performance Channel API. I suppose the reasons for that are the following:
- Channel API supports only server->client communication. To send messages from client to server I had to use usual http requests through ajax. Meanwhile, socket.io supports two-way communication.
- Channel API doesn't support broadcasting of messages (sending them to all clients). So I had to track current connected clients and send them the messages.
One more thing which I have noticed:
It seems that if you send many messages through Channel API they don't always arrive in the order in which they hsd been generated. I am not sure about that, but the code, which I wrote using Channel API behaves a little bit buggy: instead of ending a line and starting a new line, it can connect the end of the first line with the beginning of the second line (this can happen especially if you draw quickly). Although, I don't have that problem with that same code while using socket.io.
Here is the link to demostration of the application's performance: http://youtu.be/sI1hb-ybb5w
As you will see, my the application is pretty slow and there is a lot to be done, but it's enough for comparison of Channel API and socket.io.