I´m using IIS 5 with ASP NET 2.0. I´ve develop an isapi application. the response content type its text/hml it´s posible chaged to text/xml
In general, the handler which generates the response should own its Content-Type because it should be the only entity that knows the true "type of content" that is generated.
Thus, I recommend that you change the ISAPI application to have the right logic to output the right Content-Type.
If you cannot change the ISAPI application to send the right Content-Type, then you need to put this logic elsewhere:
I do not know WHY you want to do this, but what you want to do does not appear to be architecturally sound.