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Chapter+9+-+1 - Process Modeling Chapter 9 Models: Logical...

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Process Modeling Chapter 9
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Models: Logical and Physical Logical Model Nontechnical pictorial representation that depicts what a system is or does. Synonyms are essential model , conceptual model , and business model . High-Level Picture. Physical Model – Technical pictorial representation that depicts what a system is or does and how the system is implemented. Synonyms are implementation model and technical model . Detailed Architecture. Model – a pictorial representation of reality.
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Why Logical System Models Logical models remove biases that are the result of the way the system is currently implemented, or the way that any one person thinks the system might be implemented. Logical models reduce the risk of missing business requirements because stakeholders are too preoccupied with technical results. Logical models allow us to communicate with end- users in nontechnical or less technical languages.
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Process Modeling and DFDs Process Modeling – Technique used to organize and document a system’s processes. Flow of data through processes Logic Policies Procedures Data Flow Diagram (DFD) – Process Model used to depict the flow of data through a system and the work or processing performed by the system. Synonyms are bubble chart, transformation graph, and process model. The DFD has also become a popular tool for Business Process Redesign (BPR).
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Simple Data Flow Diagram
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Differences Between DFDs and Flowcharts Processes on DFDs can operate in parallel (concurrently) Processes on Flowcharts execute one at a time. DFDs show the flow of data through a System. Flowcharts show the flow of control (sequence and transfer of control). Processes on a DFD can have dramatically different timing (daily, weekly, on demand). Processes on Flowcharts are part of a single program with consistent timing.
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External Agents Outside person, unit, system, or organization that interacts with a system. Also called an external entity . External Agents define the “boundary” or scope of a system being modeled. As scope changes, external agents can become processes, and vice versa. Almost always one of the following: Office, department, division. An external organization or agency. Another business or another Information System. One of System’s end-users or managers Named with descriptive, singular noun Gane and Sarson shape DeMarco/Yourdon shape
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Data Stores Stored data intended for later use. Synonyms are file and database . Frequently implemented as a file or database.
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Chapter+9+-+1 - Process Modeling Chapter 9 Models: Logical...

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