Q:

Migrating a large classic ASP page to php?

We've got a large classic asp application and we consider migrating to either asp.net or php. I don't want to talk about the pros and cons of either one, but I'd rather like to know whether there are ways to avoid a complete rewrite in one shot when migrating to php. We simply can't stop maintaining the current codebase just to do a rewrite. So things have to go hand in hand.
If we'd move to asp.net, we should be able share session data among both technologies and have parts of the site replaced with new asp.net code, while other just keep on running. Is such an approach possible with php? Does anyone has got experiences with such a migration or could point me to some good readings?

A:

The ability to share session state between ASP Classic and ASP.NET isn't an intrinsic feature of either language, though it's fairly easy to accomplish.
Microsoft provides sample code:
http://www.google.com/search?client=safari&rls=en-us&q=share%20session%20data%20between%20ASP%20and%20ASP.NET%20pages&ie=UTF-8&oe=UTF-8
By using Microsoft's example, you could pretty easily implement something similar in PHP. Basically you'd use the ASP Classic portion of Microsoft's code above.  Then in PHP you'd write a fairly simple class to read session state from the database into an array or collection when each page is loaded.  It's a little extra work in PHP, but shouldn't be more than a few extra days of coding and testing.
PHP runs pretty well on IIS6 in my limited experience and support for it is supposedly even better in IIS7.  The only snag I've hit in  is that a most of the PHP code out there assumes you're running on Linux/Unix... but generally this is only an issue for file-handling code (think: user image uploads) that works with local filesystem paths.  Because they assume your filesystem uses / instead of \ like on Windows.  Obviously fairly trivial to fix.  
Good luck!  

