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DFD_creation_steps - II Draw the Level-0 Diagram a Think of...

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Steps for Creating DFDs I. Draw the Context Diagram (CD) a. Decide the scope of the system and who/what department “owns” the system (this establishes the Point of View, determining what is inside/outside the system) b. Decide on a good name for the system; draw and label the process box c. Decide what the outside entities are; draw and label them d. Identify an element of data that flows to/from OEs and process box; draw and label it e. Identify another data flow (DF); draw and label it (continue until no more are found) f. Re-read the scenario to ensure everything there is properly represented g. Make sure no rule violations exist: i. At least one DF comes in and one DF comes out of the process ii. DFs coming in and out are not exactly the same iii. All DFs either end or start with the process iv. All DFs are unidirectional, not recursive v. DFs that fork have only one kind of data flowing vi. DFs, OEs, and Process labels are all noun phrases vii. No Data Stores appear on the CD
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Unformatted text preview: II. Draw the Level-0 Diagram a. Think of ways to decompose the process box into 3-5 two-word phrases (in Verb-Direct Object form); write them down. Analyze your choices to see if they cover everything the system does. b. Sequentially order the 3-5 phrases; draw the process boxes in left-to-right sequential order. c. Draw the same outside entities as you had on the Context Diagram d. Draw the same DFs that connected with the OEs on the CD, but now link them each to/from the most appropriate level-0 process box. e. Identify data flows that occur between processes; draw and label them f. Identify data stores; draw and label them g. Identify data flows between processes and data stores; draw and label them h. Make sure no rule violations exist i. [repeat checks i.-v. from CD list above] ii. DFs, OEs, and process labels are noun phrases; processes are verb phrases iii. Check for DFD consistency between the CD and the Level-0....
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