In his most recent post Matthew Weier O'Phinney (lead on the Zend Framework project) takes a look at the PHP Interoperability Group (php-fig) and some recent discussions that have come up about shared interfaces for things like logging and caching.

A little over a year ago, there was a new push by a number of folks wanting to do more. Paul Jones did a remarkable job of spearheading the next two standards, which centered around coding style. [...] And this is when we started seeing proposals surface for shared interfaces, first around caching, and now around logging (though the latter is the first up for vote).

He talks a bit about shared interfaces - what they are and what kind of problem they aim to solve - and how he's not sure he "buys into them". He notes that "sharing is good, developing solutions is better" and stresses making it easier to operate with each other and not worry so much about standardized interfaces.

He's found a few problems with the concepts behind them like the Not Invented Here (NIH) idea they promote and that there's not really just a single solution to these kinds of problems ("space for multiple implementations"). He suggests an alternative to the idea of these shared interfaces - bridges/adapters. He illustrates this idea with some code showing the implementation of a "CacheInterface" and a "FrameworkACache" adapter that wraps the functionality of a "CacheItem" class that might be internal to your application already.