This presentation was part of a 2-day workshop provided for the Australian Bureau of Meteorology during 15-16 October 2007. The workshop targets system administrators whose task is to setup a data service for interactive users, batch processes, and high level web services, that will access netcdf, hdf, or freeform data in a file system or SQL data in a database. The workshop provides them with the information they need to install and configure Hyrax along with some background on available clients so they can test their servers and give basic advice to users. Summary of the slide deck: The slide deck presents the importance of defining use cases for OPeNDAP, emphasizing that they should encompass all relevant system behaviors to ensure users' goals are met effectively. Use cases are described as prose descriptions of system behavior when interacting with the outside world, capturing functional requirements and guiding IT system development. Examples include making datasets available for internet access, providing browse and quick look access to climate data, and supporting high-performance data transfer for analysis. Roles and skill sets needed for developing use cases are outlined, along with resources for writing them effectively. The presentation concludes with advice on how to respond when asked about use cases, highlighting the importance of knowing and understanding implemented use cases to develop solutions effectively.