A framework of a service directory that can handle service records
changing rapidly is provided by using a content-based routing network. A
directory node for providing the service directory is called a data
resolver. The data resolver listens for service advertisements for
certain service categories from service providers, and stores such
advertisement data in the form of service records in a local cache. If a
data resolver receives a query for some services, it first looks in the
cache. If the cache contains at least one service record that satisfies
the query, the data resolver returns the record. Otherwise, the data
resolver issues a secondary query corresponding to the query it received,
to other data resolvers connected by the content-based routing network.
Simultaneously, the data resolver begins listening for service
advertisements (service records) from other data resolvers on the
content-based routing network.