Wednesday, 19 September 2012

The simplest chat ever... just got simpler

In my last post I described a simple chat implementation using the SignalR framework. At the time of writing it I thought it’s really as simple and clean as it can get. However, my work colleague Lukasz Budnik proved me wrong by suggesting a simpler solution that they used while creating portal. He suggested replacing my server side components with a cloud hosted push notifications provider.

I admit I was thinking in a more traditional way, where all application components are hosted in-house, on servers owned by our company or our clients. Nowadays, it’s often a better idea to use exiting cloud hosted solutions than implementing some system components by ourselves. I definitely recommend considering this option if you have no important blockers preventing you from using SaaS solutions (e.g. like legal issues related to sending some data to third parties). Advantages that come with cloud are topic for another discussion though.

Let’s have a look how our chat application changes with this new approach. First of all, we need to choose a push provider. And yet again - Lukasz to the rescue with his latest post, describing various SaaS solutions. I decided to go with the PubNub, as its documentation already contains a chat example. So it’s a no-brainer, really.

The entire solution is now enclosed within a single html file. As mentioned at the beginning you don’t need to write any server code. The additional benefit is easier development and testing, as you don’t even need a web server, just your regular web browser.

The html file looks as follows. Please note that the html components are exactly the same as in my previous solution. In addition, PubNub allows you to bind events to DOM elements, so we don’t need jQuery in this example.

<label for="nick">Your chat nickname:</label>
<input id="nick" name="nick" type="text" />
<label for="message">Message:</label>
<input id="message" maxlength="100" name="message" type="text" />
<div id="chatWindow"></div>

<div pub-key="MY_PUBLISHER_KEY" sub-key="MY_SUBSCRIBER_KEY" ssl="off" origin="" id="pubnub"></div>    
<script src=""></script>
<script type="text/javascript"></script>

<script type="text/javascript">
(function () {
    // declare some vars first
    var chatWin = PUBNUB.$('chatWindow'),
        nick = PUBNUB.$('nick'),
        input = PUBNUB.$('message'),
        channel = 'chat';

    // subscribe to chat channel and define a method for handling incoming messages
          channel: channel,
          callback: function (message) {
              chatWin.innerHTML = chatWin.innerHTML + message;

     // submit message to channel when Enter key is pressed
     PUBNUB.bind('keyup', input, function (e) {
         if ((e.keyCode || e.charCode) === 13) {
                 channel: channel,
                 message: nick.value + ': ' + input.value

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