B-Spec Review Phil Pratt-Szeliga CSE 784 Fall 2009

B-Spec Review Start with a context diagram Expand out the oval that represents your program into a Data Flow Diagram Paint Windowing System File System Filenames Mouse Coordinates Tool Selections Save Commands Drawing Directions File Contents Filenames

B-Spec Review Create major processes and associate “shalls” to each one Create sub processes when a major process is complex Make sure the inputs and outputs to a set of sub processes exactly match the inputs and outputs of the parent process Data flow diagrams should really be called information flow diagrams  The flow between processes is actually information

B-Spec Review Make sure that shalls describe what the software shall do, not how Example:  Good: The Login Process shall accept a username and password during a login attempt. If the username and password supplied matches a username and password pair in the users storage then the login attempt shall succeed. If a login attempt succeeds then the login process shall return a session id and a privilege level to the caller. If the login attempt fails then the login process shall return 0 as the session id. Each time a login attempt passes a new unique (unique to the current server) session id shall be returned to the caller.

B-Spec Review “Shalls” should be  Brief  Complete  Unambiguous  Testable  Without Design Details