Re: Websockets on the IBMi

From: Kevin Turner
You can observe an open WS connection using something like wireshark.

Okay, I downloaded Wireshark and monitored the traffic for the chat and canvas demos at http://jwebsocket.org

Now I'm more skeptical about Web Sockets than I was before. The Web Socket clients continuously periodically poll the server, even while idle. Lots of HTTP [ACK], [FIN, ACK], [SYN], [PSH, ACK] and Keep-Alive requests. The packets are smaller than those associated with XMLHTTPRequests, but there are a lot more of them, so ultimately you may be transferring more data across the wire with Web Sockets.

Entering "Hello" in the chat service generates at least 300 bytes of traffic; more if a 2nd chat client is listening.

All of a sudden I see a burst of packets flying across the screen even though there has not been any chat activity. The chat client shows "org.jwebsocket.plugins.canvas" messages, even though none of my browser windows are using the canvas demo. That's just weird.

I'm not convinced that the extra 250 bytes of http header data associated with XMLHTTPRequests is more overhead. It gets compressed to 40 bytes if the server has compression on. It takes less than a millisecond to transfer 40 bytes over 2 Mbps bandwidth, which is pretty low bandwidth.

-Nathan.