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Process Modeling and Data Flow Diagrams (Supplemental)

Process Modeling and Data Flow Diagrams (Supplemental). 4 types of Models.

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Process Modeling and Data Flow Diagrams (Supplemental)

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  1. Process Modeling and Data Flow Diagrams(Supplemental)

  2. 4 types of Models • Logical models show what a system ‘is’ or ‘does’. They are implementation-independent; that is, they depict the system independent of any technical implementation. As such, logical models illustrate the essence of the system. Popular synonyms include essential model,conceptual model, and business model. • Physical models show not only what a system ‘is’ or ‘does’, but also how the system is physically and technically implemented. They are implementation-dependent because they reflect technology choices, and the limitations of those technology choices. Synonyms include implementation model and technical model

  3. 4 types of Models (cont.) • As-Is (Current System) • To-Be (Future System) • To build ”To-Be” model we try to formalize problems of “As-Is” model and propose the solutions to those problems. The result of such work is the “To-Be” model. Note that “To-Be” model is our vision of the ideal future.

  4. Common Mechanical Errors

  5. Illegal Data Flows

  6. Logical Processes • Logical processes are work or actions that must be performed no matter how you implement the system. • Even for the future system, at the definition phase, the process model should be logical. • In the study phase, the current system was analyzed in three levels of models: • Context Diagram • System Diagram (Level 0) • Event Diagrams (Level 1, level 2, …)

  7. How to Model a New System • Step 1: Identify the changes in functional requirements for the new system • Step 2: Establish the context for the new system • Step 3: Create a new system diagram • Step 4: Create necessary child diagrams

  8. Identify the changes in functional requirements for the new system • Source: Problem Statement (Cause/Effect) • Prioritize the “System Objectives” based on the urgency/importance of the effects • Regroup the objectives into changes in functional requirements e.g., • Operational requirements, • Reporting/Inquiry requirements

  9. Establish the context for the new system • Analyze the new functional requirements in terms of necessary input/output of data i.e., • Is there any new input? • Is it necessary to produce new output? • Is it going to allow new functions to external entities?

  10. New Context Diagram

  11. Create a new system diagram • Principles for creating new DFD • Keep the model simple • Try to use data stores to connect all the processes • Identify the functions that must be affected by the new functional requirements • Add necessary data stores • Determine the boundary of the new system

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