URL Rewriting: Part Two: How?
26th October 2007 by Joe Bursell
In "URL Rewriting: Part One: Why?" I talked about dynamic URLs and their limitations. Here I’ll describe the ways in which they can be modified for search engine friendliness (and other benefits).
Simply put, a dynamic URL is a locator that contains a variable element (that’s the bit that makes it "dynamic", usually a call to a database) e.g. http://www.example-site.com/cgi-bin/gen.pl?id=154&view=basic …in this instance it’s the query-string beginning "id=XXX".
When a search engine interrogates this URL it’ll strip the noise out, and by noise I mean everything after the "?". The result is that instead of seeing many distinct URLs such as
http://www.example-site.com/cgi-bin/gen.pl?id=466&view=
http://www.example-site.com/cgi-bin/gen.pl?id=467&view=
etc. the search engine will just see loads of duplicates:
http://www.example-site.com/cgi-bin/gen.pl
http://www.example-site.com/cgi-bin/gen.pl
etc. which will be ignored. The outcome is that only one URL is recognised, and it’s not descriptive enough to provide search information, so your many, many products won’t get the visibility you desire.
By rewriting the URL you apply some rules to translate the indecipherable portions and clear out the noise, making the URL easily readable. Of course your site still generates dynamic locators, its just that they are squirted into a manageable/readable format. The search engines can now read them, there’s no dupes, and Mr. Hacker will have difficulty telling the difference.
The tools available for URL rewriting vary from platform to platform, the most popular being ISAPI_Rewrite, and IIRF (free, from http://www.codeplex.com/IIRF) for Windows IIS and mod_rewrite for