title: Whenever RewritePath() is called, Page.IsPostBack is false
body: <p>I'm developing a custom URL Rewriter for a ASP.Net 3.5 project. This rewriter is not functionally different than most rewriters out there, the only difference being that the friendly URL collection is not loaded from a web.config file -- it's coming from a database instead. I made the naive assumption that it would be easy to develop a custom rewriter module from scratch, but now I know the mess I put myself in. I digress; let's go straight to the technical issues.</p>
  
  <p>While testing the rewriter, I set up a friendly url that would take the user to a web form. Postbacks from this form should not alter the friendly address, as anyone would expect, so</p>
  
  <p><code>http://my.web.site/app_root/FriendlyURL</code> is always rewritten as <code>http://my.web.site/app_root/not_friendly/form.aspx</code></p>
  
  <p>Things are fine when the browser first loads the FriendlyURL. The page comes up and is completely functional. However, when the form is posted back to the server, the page simply reloads but, at server-side, <code>IsPostBack</code> is false. It's like F5 was hit, except that a HTTP POST had indeed occurred.</p>
  
  <p>Unsurprisingly, when the interaction occurs through the "unfriendly" URL, the POST action triggers the postback as expected. This evidence suggests that <code>HttpContext.RewritePath</code> is somehow messing with the page lifecycle in a way that it loses sense of the postback operation. Any directions? Thanks.</p>