One of the key differences to the Zaltana method of apache modules to the majority of apache modules, is that they are written to work independent of the storage/handler for generating the content - even when they themselves are handlers are not just filters !

So what does this mean?

Example - Subversion

Apache2 has a nice module which is one of the best ways to present a Subversion repository.

Here is an example image in one of our local Subversion styles.

<img src="http://www.zaltana.org/project/zaltana/Style-Core/trunk/preview.jpg"/>

Now we want to get a Thumnail version of this image. Here I am using the "prefix" method used in Apache Image to get a thumbnail.

<img src="http://www.zaltana.org/z/image/thumbnail/project/zaltana/Style-Core/trunk/preview.jpg"/>

Authentication / Access control / Security

Subproc method uses the current user and security requirements to access the system underneath. This means you can't break security. You are leaving it in the place it is supposed to be - Apache Auth systems.