Question

During development, I usually test ASP.Net applications using the Web Development Server (sometimes called Cassini). Occasionally, when I publish to a real IIS environment, I notice that the application behaves differently.

So, what are the differences between the way that production IIS servers and the ASP.Net Web Development Server behave? I don’t mean differences in feature sets (clearly IIS has lots of features that are not present in WDS), but differences in the way they handle ASP.Net.

BTW: There are a few differences noted in the responses to this question, but I am sure there must be more.

Answer 1

Some differences might be:

• You can’t use virtual directories while working with cassini. This might lead to unexpected behaviour when deploying for the first time, due to missing folder permissions. (e.g. You have a /image/ directory on your local machine, but in the IIS /image/ is the virtual directory pointing elsehwere)
• Some
  third party assemblies (like ComponenArt Web DLL) cause problems
  with specific port issues. It’s best
  to develop with the IIS to minimize
  compability problems on deploying.
• The trustlevel of the target IIS might be
  lower that your development settings,
  this might result in malfunctioning,
  depending on what you do with the
  IIS, like reading the Uptime.