A key aspect of the service-oriented architecture approach for middleware is that services advertise themselves using directory or lookup services so that prospective clients can find them. The service location and discovery abstractions required to support this are not much different from those we use to conduct business with other people. As a result, we can gain insights into how distributed service discovery systems work by comparing them to everyday human-oriented service discovery approaches. Given that service discovery depends on discovery services, how does an application actually find a discovery service?.