I understand that Server.Transfer doesn't make a round trip back to the requesting client.
What I haven't been able to learn is if control is simply passed directly to the new request handler you're transferring to or if or if the entire request life-cycle is executed again.
I assume the entire life-cycle is executed again using the transfer URL but wanted to verify this was the case.
Here is what I found through experimentation.
When using Server.Transfer the entire request life cycle is not ran again.
If you write your own Module, hook it into the request life cycle, and call Server.Transfer from that module the rest of the request life cycle will be skipped and the page life cycle will begin immediately.
After completing the transfer page life cycle the request life cycle picks back up with its tear-down events. Note, the HtppContext in for the tear-down events will be the original one you transferred from. That is, the URL and QueryString values will be the same as the original request and not be the URL and QueryString values for the page you transferred to.
Server.Transfer does modify the HttpContext.Request object to contain the new URL and QueryString information during the page life cycle for the page you transferred to.
If you transfer to a resource that is not a page but is text based (e.g. something.xml) the content of that page will be returned exactly as is with its encoding set to text/html.
If you transfer to a resource that is not a page and is not text based (e.g. something.pdf) then an HttpException error will be thrown. This happens even if you have defined a custom Handler for this resource.
It's just passed along, with its state intact. The request lifecycle does not get run again, although the page lifecycle will run for the page you're transferring to.
http://msdn.microsoft.com/en-us/library/ms525800(v=vs.90).aspx
Server.Transfer acts as an efficient replacement for the Response.Redirect method. Response.Redirect specifies to the browser to request a different page. Because a redirect forces a new page request, the browser makes two requests to the Web server, so the Web server handles an extra request. IIS 5.0 introduced a new function, Server.Transfer, which transfers execution to a different ASP page on the server. This avoids the extra request, resulting in better overall system performance, as well as a better user experience.
This link is also helpful -
http://www.developer.com/net/asp/article.php/3299641/ServerTransfer-Vs-ResponseRedirect.htm
