Methods and apparatus, including computer program products, that include representing, in a repository, services from a server, the services including interacting with one or more collections of data elements using a set of operations on the data elements in the collections, the repository comprising descriptions of the collections and common attributes for each collection, the repository organized according to a meta model. The method also includes enabling a software entity to request a service represented in the repository, the service representing a first operation on one or more data elements in a first collection from the collections, and executing the first operation on the one or more data elements in the first collection.