Websockets by Andrew Lombardi

Author:Andrew Lombardi
Language: eng
Format: mobi, epub
Tags: COMPUTERS / Programming Languages / JavaScript
ISBN: 9781491918302
Publisher: O’Reilly Media
Published: 2014-10-21T04:00:00+00:00

SockJS Chat Client

Let’s walk through how to convert the client to use the SockJS library.

First thing you’ll need at the very beginning of any other JavaScript will be to include the SockJS library.

<script src="http://cdn.sockjs.org/sockjs-0.3.min.js"></script>

This library provides the SockJS object which mimics the WebSocket library included in most modern browsers. The initialization also changes as we are not using the ws or wss protocol, but instead using http as the initial transport.

var sockjs = new SockJS("http://127.0.0.1:8181/chat");

For our WebSocket client code we used the variable name ws. Here it seems more appropriate to rename it to sockjs. Find all instances of using ws in the code from Chapter 3, and replace them with sockjs. That is the extent of the changes required for the client. SockJS delivers nicely on an easy migration from native WebSocket to their library.

They offer support for one or more streaming protocols for every major browser which all work cross-domain and support cookies. Polling transports will be utilized in the event of older browsers and hosts with restrictive proxies as a viable fallback.

In the next section we’ll take on changing our chat application to use the Socket.IO platform instead.

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