I'm doing some work on a web service that stores XML documents. The web method that stores a document returns a URL as a unique identifier for the document. That URL can later be used to view/edit the document on a web site. Since I'd like the web app to be "portable" in the sense that it generates URL's correctly regardless of where it is hosted, I need to build the web app's URL dynamically. I ran across the following blog entry that had some good tips.