it'd probably be a perl module invoked from within a web application. It's not meant to mirroring a website / webpage, just to save a "local copy" of a single html site for future reference. The web application is meant to analyze parts of the html code and give some results; and it should keep a local copy of the page it analyzed and of the report it generates, because web content may change at any time. So the web application can say "this is a report on our results on this web page, and this is what the page looked like (or: This is the web page's code) at the time we analyzed it".