Programmatically Adding IIS Application Extension Mapping using .Net C#

Application Extension Mapping can be programmatically added using "DirectoryEntry" class in "System.DirectoryServices" namespace.

using System.DirectoryServices;


	public class DirEntry
        {

	public void SetSingleProperty(string metabasePath, string propertyName, object newValue)
            {
                //  metabasePath is of the form "IIS://servername/path"
                try
                {
                    DirectoryEntry path = new DirectoryEntry(metabasePath);
                    PropertyValueCollection propValues = path.Properties[propertyName];
                    string oldValue = propValues.Value;
                    path.Properties[propertyName][0] = newValue;
                    path.CommitChanges();
                    Console.WriteLine("Done");
                }
                catch (Exception ex)
                {
                    if ("HRESULT 0x80005006" == ex.Message)
                        Console.WriteLine(" Property {0} does not exist at {1}", 
propertyName, metabasePath);
                    else
                        Console.WriteLine("Failed in SetSingleProperty with the 
following exception: \n{0}", ex.Message);
                }
            }

	}

"SetSingleProperty" method can be used to add any DirectoryEntry. For adding IIS Application Extension Mapping "ScriptMaps" Property to be added. i.e

DirEntry de = new DirEntry();
de.SetSingleProperty("IIS://localhost/W3SVC/1/ROOT", "ScriptMaps", 
@".htm,c:\windows\microsoft.net\framework\v2.0.50727\aspnet_isapi.dll,5,GET, HEAD, POST");