Lab 3 Level of DFD Level0 DFD Shows

Lab 3 Level of DFD Level-0 DFD Shows the system’s major processes, data flows, and data stores at a high level of abstraction When the Context Diagram is expanded into DFD level-0, all the connections that flow into and out of process 0 needs to be retained. A data flow diagram (DFD) that represents a system’s major processes, data flows and data stores at a high level of detail

Decomposition of DFDs • Functional decomposition Act of going from one single system to many component processes Repetitive procedure

• Level-N Diagrams A DFD that is the result of n nested decompositions of a series of sub processes from a process on a level -0 diagram Lower-Level Diagrams

Functional Decomposition * An iterative process of breaking a system description down into finer and finer detail. * detailed DFDs to describe an IS Balancing.

* The conservation of inputs and outputs to a data flow process when that process is decomposed to a lower level Ensures that the input and output data flows of the parent DFD are maintained on the child DFD

Guidelines for Drawing DFDs • Completeness DFD must include all components necessary for system. Each component must be fully described in the project dictionary or CASE repository.

• Consistency The extent to which information contained on one level of a set of nested DFDs is also included on other levels

Level-0 DFD of Order System