Forum OpenACS Q&A: Re: How to use ns_register_filter to establish a route to be served by NaviServer

Here is a diagram to visualize the differences between procs in the filter chain (filter procs) and the usual request content handlers ((pre-) registered procs stored on disk or in handlers).

Note that the filters are less efficient, since for every incoming request, all filters procs of a filter chain are sequentially matched and are potentially executed, unless a filter proc terminates the chain explicitly. This happens for every filter chain. Under certain uncaught error conditions, some of the steps are skipped.