URL rewriting

In the past I linked to an article on URL rewriting and how to do it.  This past weekend I finally modified my personal web site to use URL Rewriting.

 

I tried a couple different methods of URL Rewriting and finally settled in with http://www.urlrewriting.net as the documentation was good and the implementation fit my needs.

Essentially all that was required was to drop the urlrewriting.dll into my bin directory (adding it as a reference for my website) and adding rewriting rules to my web.config.

 

The power is in adding rewriting rules to the web.config.

You create the functionality you want as query string variables, and then create a rewriting rule.  The rewriting rule defines a regular expression of the "to be" URL and how it maps to the real url.

For example:  I am using an imagehandler.ashx file to resize images on the fly.  It takes query string parameters:

dir: the subdirectory of my pictures directory to use

file: the picture in that directory to use

width (optional): how wide to make the output picture

height (optional): how tall to make the output picture

This results in a url like this:

http://www.jessandrob.com/imagehandler.ashx?dir=Alberta-Aug-2007&file=DSC00105&width=800&height=600

Which clearly isn't to friendly.

After adding the reference I added this to the web config:

<urlrewritingnet xmlns="http://www.urlrewriting.net/schemas/config/2006/07">

<rewrites>
<add name="picture_web" 
ignorecase="true"
virtualurl="^~/gallery/web/([\d\w\s\-]*)/([\d\w\s\-]*).aspx"
destinationurl="~/ImageHandler.ashx?Path=$1&File=$2.jpg&width=800&height=600"
rewriteurlparameter="ExcludeFromClientQueryString" />
</rewrites>

</urlrewritingnet>

After this the url becomes:

http://www.jessandrob.com/gallery/web/Alberta-Aug-2007/DSC00105.aspx

 

You can see my regular expression is matching digits, letters, whitespace, and dashes for both the directory name and the file name, and they are passed to the query string as "$1" and "$2" per standard Regex notation.

Notice its .aspx instead of .jpg - this seems to be a limitation of IIS.  using ".JPG" actually works in the Visual Studio built in web server but fails in IIS - that's something I'll have to look into in the future.

Yes its that simple.  I repeated the process for a couple other dynamic pages.

The one thing that did effect me a bit was URL's on the rewritten pages - you'll notice that the rewritten pages are deeper directory wise than the original - this is my design choice.  This caused issues on the pages mapping relative urls - specifically I needed to utilize the ASP.NET "~" operator and have the url as runat=server (this was ASP.NET figures out the relative url for me).  Where this isn't possible I have to manage the urls a bit more manually.