Web Sockets: Random Number Streaming

I have recently been playing with web sockets because I wanted to get a better understanding of how to use them. A web socket is a full duplex TCP connection between web browsers and web servers. This is not to be confused with earlier techniques with similar aims like long-polling and Comet. Web sockets actually have their own RFC. They are a standard. All the major browsers have implemented it. This means web sockets are not tied to any particular language or server. Below I will show using web sockets in plain JavaScript, Node.js, and Java.

Node.js Server

Here is a Node.js server that sends a random number to everyone connected to it, every second, on the same channel. Obviously this is not that useful, but it could represent a stock price for example. I found the ws module to be easy to use for the web socket server implementation. Another module socket.io seems to be more popular but you need to use it in the client as well. For this learning exercise I wanted to use native web sockets in my client.


Java Server

Here is the same random number sender implemented in Java. I ran this on the recently released WebSphere Liberty Profile 8.5.5.2 which added a web socket feature (full disclosure I work closely with this product at IBM).


JavaScript Client

My client can talk to both servers. I probably went overboard, but I used the same MVC-style from my Client-side MVC with JavaScript blog. The important part is lines 9 through 12.


A screenshot of the client receiving random numbers from the Node.js server: