SHARK started as a way to dynamically create nearly static web pages, as those of rrdUtils or stats collector. Thus, it was initially only a replacement for a small set of shell scripts, executed offline every time that one element was modified. But, even at the very initial state, it was clear that is was actually a framework, where might fit many web applications.
SHARK shows a list of available actions, which may be grouped and usually refer to the same location. The usual response is to modify a portion of the webpage, not including the list of actions. It pretends to be as simple as possible, to allow the user to focus on whichever application is programming, instead of worry about the way it interacts with the web server. It is written in PHP, because it is probably the more portable language across web servers (at least Apache & IIS). Every action maps to a file named as the action, which is the associated response and could be anything requirable from PHP.
Downloadable here