From the product page

In a XML-configuration file you can specify python-functions as processors for the HTTP-messages you are interested in (requests or responses, which match certain criteria). You may have as many processors as you want, without modifying the actual program. The only thing you need to do, is configure the httpMonitor and write your processors.

The package comes with three sample processors. One for logging header-information of the HTTP messages (httpMonitor.filters.logger), one for modifying header fields (httpMonitor.filters.headermodifier) and a third one for accessing (and modifiying) parsed html-text. The processors can be configured to tell them exactly what to log or what to modify.