[ServiceContract(Namespace = "http://www.temporary.com/akiii")]
Service contract namespace is to use to avoid collision of different or other classes or interfaces when we are using the above service in a service oriented architecture(SOA). It can be anything and the http doesn't really matter here, it can be anything from your name to country name...anything !
Ideally, it should be the domain name registered followed by some fully qualified domain address.
Thanks and Regards