ITEC 3010 Lecture Notes - Lecture 6: Data Flow Diagram, System Context Diagram, Data Store
8 Mar 2020
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Data flow diagrams and levels of abstraction: levels of abstraction, decomposing the set into more detailed sets, higher levels are generalized vs lower levels are detailed. The event-partitioned system model: dfd models requirements using single process for each event, diagram 0/event partitioned system model: the entire set of fragments that can be combined into a single dfd, shows entire system, slide 17. Summary of relationships of all these diagrams: context diagram subsystem diagram event partitioned subsystem diagram. Decomposing processes to see details of one activity: take dfd fragments and decompose it into sub-processes. Documenting data flow diagram (dfd) components: process descriptions, each process on dfd need to be defined by breaking down dfd to more detailed. 7th: step 5, last row: the actions for each possible condition, may be several actions w/ a set of conditions i. e. calculating shipping charges . Decision tree : easier to read than table and developed in the same way.
