Caching

Lately I have had "caching" on the brain and have been working on a decent way of caching.

So far I have found that caching is obviously faster and in XML format makes it really easy to iterate through in Object format.

My methods so far are

1. Checking a database table for current cached item information.
2. If it has an expiration date or does not exist the feed needs to be cached.
3. If needs to be cached - Caching will grab the feed via curl, fopen, or file_get_contents()
4. Feed will then be stored in a file in a specific directory on the server. 
5. Database will either be updated or inserted with feed information.

Right now I am thinking about having a hybrid method here that will come up with a way to setup expirations inside of the "feed." But I still like having information in the database as then I can loop through old archived feed information if I want to.

The functions I am using goes as follows:

1. MySQL Query to check database for cached item. Creating a couple different unique identifiers such as URL, location, etc...
2. PHP function "SimpleXMLElement"

Function basically makes an xml string and converts it to an object format.
Iterating is as easy as doing the following:

$xml = new SimpleXMLElement($cached);
	if(is_object($xml))
	   foreach($xml->channel->item as $k=>$v){
                echo $v->title;
           }

The above I use on either the new cached item or the old stored feed. Typically my caching time varies. For something like a twitter feed I cache for about 2 hours. On other feeds I have no expiration set as they should be recached "manually" For instance recently I made a section in my CMS to check Facebook stats on likes, recommends, clicks etc... These are queries that query the facebook open graph and returns an XML feed. I store this feed in my cache and setup an ajax call to a page that pulls these feeds and updates the page.

Something like this is best to not pull every single time a page loads but rather every so often.