While implementing enterprise SOA, it is important to consider deploying a service catalog for services. There is a lot of confusion between the concepts of registry, repository and service catalog.
Traditionally a registry has been a lookup service provided to service consumers. Service providers register their services in the registry and service consumers select an appropriate service for their needs. Standards such as UDDI addressed these needs.The Registry would contain service descriptions, service contracts and service policies that describe a service. Service registries have also been practically used for determining a service end-point address at runtime based on the service unique name.
So what is a repository? As the importance of SOA Governance grew, it became necessary to capture more meta-data about a service. A service repository integrates information about a service from multiple sources and stores it in a centralized database. Service information may include design artifacts, deployment topologies, service code repository, service monitoring stats, etc. Vendors have started positioning their generic asset management products as SOA repositories. For e.g. Rational Asset Manager.
A lot of vendors now sell a combined product that consists of the registry and repository. For e.g. IBM Websphere Registry and Repository.
A service catalog is a concept that can be implemented using SOA registry/repository products.