Miles Johnson

Single or multiple feed aggregation?

I recently published a beta version of my feeds plugin for CakePHP. This plugin was previously the FeedAggregator component, but it made more sense to break it up into a datasource and model, and finally package as a plugin. The datasource is pretty straight forward as it accepts an array of URLs (RSS feeds), fetches each one through an HTTP request, parses the XML into an array, and then returns the result. The model is simply there for your convenience.

Now the dilemma I am running into is whether or not the datasource should only parse one feed at a time or multiple feeds (currently this). It can go either way: the datasource parses multiple feeds and uses the model to return them, or the datasource parses one feed and the model manages multiple connections and merging. Now the big question for you guys... Should the datasource parse one feed at a time or multiple feeds?

Currently you use the model to pass an array of URLs (through the conditions option), the limit, which fields (elements in the XML) you want returned, and some cache/feed settings. Here is a quick example:

// Multiple feed parsing
$feeds = $this->Aggregator->find('all', array(
	'conditions' => array(
		'Starcraft 2 Armory' => 'http://feeds.feedburner.com/starcraft',
		'Miles Johnson' => 'http://feeds.feedburner.com/milesj'
	),
	'feed' => array(
		'cache' => 'feedCacheKey',
		'expires' => '+24 hours',
		'explicit' => true
	)
));

And I am assuming single feed parsing would look something like this:

$feed = $this->Aggregator->find('first', array(
    'conditions' => array('http://feeds.feedburner.com/milesj'),
    'feed' => array(
        'cache' => 'feedCacheKey',
        'expires' => '+24 hours',
        'explicit' => true
    )
));

I am kind of split on how I should go about this and would really love your opinion. I am currently leaning towards multiple feed parsing (current implementation), but if someone has a good argument in not doing so, I will change it.

Pitfalls within Cake's Cache engine

For the past week I have been working on a DataSource for the WeGame API. Everything was working fine until I added some logic to cache the results. No matter what I did I received the following fatal error:

//Fatal error: Call to a member function init() on a non-object in C:\xampp\htdocs\cake_1.2.5\cake\libs\cache.php on line 195
// Line 195
$_this->_Engine[$engine]->init($settings);

The error was being thrown from within Cache::set() and it seemed to fail because the actual storage engine object was not instantiated. I spent a good couple hours trying to track down the bug, but to no avail. I tried removing Cache::set(), placing Cache::config() within config/core.php, but still nothing.

Finally I thought to myself "Let me check my Config settings", so I did. I noticed that Cache.disable was set to true, and once I set it to false the whole system worked! Bah, pretty annoying right? I sure love Cake, but its error and exception handling isn't that great. I've ran into so many of these case scenarios where a simple trigger_error() or uncaught exception would of helped (This is for you Cake team *cough*2.0*cough*).

Another thing I would like to note, is that the path option in Cache::config() does not actually create the folder, you must do that manually. Here's how I resolved that problem.

$cachePath = CACHE .'we_game'. DS;
// Create the cache dir
if (!file_exists($cachePath)) {
	$this->Folder = new Folder();
	$this->Folder->create($cachePath, 0777);
}
Cache::config('weGame', array('path' => $cachePath));