How Can a LAMP Guy Easily Implement WebSockets?

Question

I've always worked with Apache, MySQL, and PHP. I'd like to eventually branch out to Python/Django or Ruby/Ruby on Rails, but that's another discussion. Two great things about Apache, MySQL, and PHP are all three are ubiquitous and it's very easy to launch a website. Just set up an Apache virtual host, import the database into MySQL, and copy the PHP files onto the server. That's it. This is all I've ever done and all I've ever known. Please keep this in mind.

These days, it's becoming increasingly important for websites to be able to deliver data in real-time to the users. Users expect this too due to the live nature of Facebook and Gmail. This effect can be faked with Ajax polling, but that has a lot of overhead, as explained here. I'd like to use WebSockets. Now remember that I've always been a LAMP guy. I've only ever launched websites using the method I described earlier. So if I have, say, a CakePHP site, how can I "add on" the feature of WebSockets? Do I need to install some other server or something or can I get it to work smoothly with Apache? Will it require Apache 2.4? Please explain the process to me keeping in mind that I only know about LAMP. Thanks!

Answer 1

One key thing to keep in mind, is that a realtime websockets server needs to be "long running", so that it can push stuff to clients. In the classic LAMP setup, Apache spawns a PHP interpreter on each request. Between requests the PHP interpreter is not running, and the only protocol state kept between requests is sessions.

One nice property of the LAMP way, is that memory management is easy. You just implicitly allocate whatever memory you need, and it is automatically reclaimed when the request is done, and the PHP process exits. As soon as you want the server to keep running, you need to consider memory management. In some laguages, like C++, you manage allocation and deallocation explicitly. In other languages, like Java or Javascript, you have garbage collection. In PHP you throw everything away, and start with a fresh slate on each request.

I think you will have a hard time making long running servers with something like Cake or any other classic PHP framework. Those frameworks works by basically taking an HTTP request and turning it into an HTTP response.

My advice is that you should look into something like Node.JS and SocketIO. If you know Javascript, or don't mind learning, these technologies allow you to easily implement real-time servers and clients. If necessary you could run a reverse proxy like nginx, so that your existing LAMP stack would get some requests, and one or more NodeJS servers would get some.

This answer came out a bit fluffy, but I hope that it helps a little.. :-)