Tuesday, March 6, 2007

Outlook Feed Bug?

I ran into this today when I was fixing up FlexWiki 2.0's RSS mechanism to work with the new security provider. I finally got the page with the links to the RSS feeds to render, and I was a bit surprised when Outlook popped up showing what was obviously an ASP.NET error message. I was even more surprised that the same URL worked just fine in IE (I'd been testing with Firefox).


A little debugging and I think I figured out what's happening. Firefox appears to be launching Outlook as the registered application for RSS documents (presumably based on the ContentType, which is text/xml). Anyway, that's fine - I use Outlook to read RSS feeds, so great. What's not great is that Outlook decided to lowercase the URL.


Hello?! URLs are case-sensitive! Who thought it was a good idea to screw with the case of URL? I mean, it's fine to write a web application that accepts either case on the server side, but you can't just send either case as a client - you have to assume case sensitivity.


FlexWiki is highly case-sensitive as part of its design. So the lowercased namespace in the URL results in a failure to look up the right information. I'd write a fix for this into FlexWiki, but frankly I'm not sure that's a good idea. Outlook seems (to me) to be pretty clearly broken on this one.


I googled (lowercase intentional) for info on this but wasn't able to turn up much. Anyone know anything?


  1. You only discovered ONE bug in Outlook's RSS implementation? WOW.

  2. Well, I've only been looking for five minutes. :)