chapter 6 structuring system requirement process modeling

chapter 6 structuring system requirement process modeling -...

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Student Cap and gown order purchase request Cap and Gown Company Entry order system C and G Company Student Order authorize Update Order final Data File 1. What is a data-flow diagram? Why do systems analysts use data flow diagrams? Data flow diagram-a graphic that illustrates the movement of data between external entities and the processes and data stores within a system. System Analysts used data flow diagrams to help them model the processes internal to an information system as well as how data from the system’s environment enter the system, are used by the system and 2. Explain the rules for drawing good data-flows diagrams? Basic rules that apply to all dfd inputs to a process are always different than outputs. Object always have a unique name in order to keep the diagram uncluttered. Process-no process can have only outputs, no process can have only inputs and, a process has a verb phrase label. Data store-data cannot be moved from one store to another, data cannot move from an outside source to a data store, data cannot move directly from a data store to a data sink and, data store has a noun phrase label. Source/sink- data cannot move directly from source to a sink and a source-sink has a noun phrase label Data flow-a data flow has only one direction of flow between symbols, a fork means that exactly the same data go from a common location to two or more processes, data stores or sources/sinks 3. What is decomposition? What is balancing? How can you determine if dfds are not balanced? Decomposition-the process of breaking the description of a system down into small components also called functional decomposition. Balancing-the conversation of inputs and outputs to a data flow diagram process when that
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This note was uploaded on 03/03/2010 for the course IT cis2321 taught by Professor Nearing during the Spring '10 term at Indian School of Business.

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chapter 6 structuring system requirement process modeling -...

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