Hi, the three definitions below are the last that are planned for the OGSA Glossary v1.5, and will be discussed on Wednesday's call. Thanks to Andreas for providing the use case and scenario definitions, and to the OGSA-D team for data federation. Please let me know if you have any comments. Thanks, - Jem Data federation: The integration of multiple services or data resources so that they can be accessed as if they were a single service. Use case: A use case captures a contract between the stakeholders of a system about its behavior. Different sequences of behavior, or scenarios, can unfold, depending on the particular requests made and conditions surrounding the requests. The use case collects together those different scenarios. OGSA use cases are high-level and described in a casual style. They are not at the level of detail required for a formal requirements analysis but are meant to provide sufficient detail to inform the architectural definition process. Source: "Writing Effective Use Cases," Alistair Cockburn, Addison-Wesley Professional; 1st edition (January 15, 2000) Scenario: A use case scenario contains a sequence of steps showing how their actions and interactions unfold. OGSA scenarios are high-level and described in a casual style. See also use case. Source: "Writing Effective Use Cases," Alistair Cockburn, Addison-Wesley Professional; 1st edition (January 15, 2000) ________________________________ Jem Treadwell Hewlett-Packard Company 6000 Irwin Road Mount Laurel, NJ 08054 Phone: 856-638-6021 Fax: 856-638-6190 E-mail: Jem.Treadwell@hp.com