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?
I created one web service. Now i want to provide it multiple URL. Using all those URL this web service can be called.
Now when the web service will be called I want to know using which URL it is called as code is same only URL is different.