APE Comet Server Local Dev Environment Setup

joe realtime, social web, webdev ape, comet, linux 4 Comments

APE (Ajax Push Engine) is a scalable comet or AJAX push server written in C.  It’s great for embedding HTML chat clients or making real-time games without Flash.

I’ve been playing around with APE for a couple different applications.  Setting up the demos on a single server that runs both Apache and the APE server is relatively straight forward.  However, running the APE server separate from the web server is not as simple.

Here’s my dev environment…

• Web server: Ruby on Rails running locally on my mac at http://0.0.0.0:3000
• APE server: running in a Debian VMWare server at http://192.168.0.99:6969

The production environment is similar with Heroku as the web server and Linode running the APE server.

Here’s what you have to do to get the dev environment setup from scratch…

1. Download APE Project
2. Follow the APE doc for installing the server
3. Create a new rails project and copy the ape-jsf folder into your rails project’s public dir
4. Edit /etc/hosts on your mac and add the entries below
5. Edit ape-jsf/Demos/config.js as directed below
6. Modify JS Request methods to use GET instead of POST

Add to /etc/hosts

192.168.0.99 ape.dummy-domain.com
192.168.0.99 0.ape.dummy-domain.com
192.168.0.99 1.ape.dummy-domain.com
192.168.0.99 2.ape.dummy-domain.com
192.168.0.99 3.ape.dummy-domain.com
192.168.0.99 4.ape.dummy-domain.com
192.168.0.99 5.ape.dummy-domain.com
192.168.0.99 6.ape.dummy-domain.com
192.168.0.99 7.ape.dummy-domain.com
192.168.0.99 8.ape.dummy-domain.com
192.168.0.99 9.ape.dummy-domain.com

0.0.0.0 dummy-domain.com

Edit ape-jsf/Demos/config.js

APE.Config.baseUrl = 'http://dummy-domain.com:3000/ape-jsf'; //APE JSF
APE.Config.domain = 'auto';
APE.Config.server = 'ape.dummy-domain.com:6969'; //APE server URL

Last but not least, edit ape-jsf/Tools/Check/index.html and modify all Request calls to use GET instead of POST.  By default, MooTools Request object uses POST for XHR requests which will cause a problem with Rails.

this.addTest('Loading Client', function() {
		var req = new Request({
			'url': '../../Clients/MooTools.js',
			'method': 'GET',
			'evalResponse': true,
			'onComplete': function(resp) {
				if (window.APE) this.fireEvent('testComplete', {'sucess': true});
				else this.fireEvent('testComplete', {'error': "Can't load client, check the file " + window.location.href.replace('/Tools/Check/', '') + "/Clients/MooTools.js is available"});
			}.bind(this)
		}).send();
}.bind(this));

The test script should now run properly at http://dummy-domain.com:3000/ape-jsf/Toosl/Check/

APE uses iframe and JSONP hacks to transparently handle javascript subdomain security issues.

If you look at what’s going on in Firebug, you’ll see APE embedding an iframe in the page, setting the iframe domain to dummy-domain.com, and making calls to the APE server through iframe.  This trick only works if the main HTML page is on a different sub-domain than the APE server.  It will not work for two completely different domains.  This is a limitation of Javascript browser security and not APE.

Thanks to the APE dev team for making an awesome comet server!