.NET AppDomain
In ASP.NET web service, use AppDomain to load and unload assembly.

Problem:
Create the assembly with same name, will get error message " access denied, the file is in use by another process"

Solution:
use AppDomain to load and unload the assembly.
Assembly itself can not be unload, so we have to create a new AppDomain and in this new AppDomain to run assembly and finally unload the AppDoamin thus the assembly.

Details:
Good entry point to find anwsers for .NET problem

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=311674&SiteID=1
and the famous paper
Eric Gunnerson has a good article on that sort of thing: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncscol/html/csharp05162002.asp

try
{
  AppDomainSetup setup = new AppDomainSetup();
  setup.ApplicationBase = m_workDir; //put all .DLL there
  setup.ApplicationName = "Mcws";
  setup.DynamicBase =  m_workDir;
  setup.ShadowCopyFiles = "true";
  setup.ShadowCopyDirectories = m_workDir;

  AppDomain appDomain = AppDomain.CreateDomain(
   "Mc", null, setup);

  SetAppDomainPolicy(appDomain);
  object o=  appDomain.CreateInstanceAndUnwrap(
       getNamespace(moduleName), //CmmCode.Math ==> CmmCode 
       moduleName);

  MethodInfo mi;
  Type t = o.GetType();
  mi = t.GetMethod(methodName);
  retVal.result =  mi.Invoke(o,methodParams);
  retVal.success = true;
  AppDomain.Unload(appDomain);
  appDomain = null;
}

- posted by Pop @ 6:03 PM