How to do what exactly? What do you mean by multiple URLs? And what exactly is "during runtime", in what bit of code do you want to check this and why?
I can make a guess (I shouldn't have to do that, you should be providing details): this is intended to deploy a webservice to different environments (test, acceptance, prod) and you need to tell your application which deployed instance of the webservice it should be calling, which you do by providing a specific URL. Am I right?