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Structured Analysis Method

Structured Analysis Method. Structured Analysis Method. Structured system analysis and design (SSAD ) Formal structured dev method Developed by UK Gov. in the 1980’s We will focus only on analysis Was used a lot when automating existing manual systems Main steps Draw a context diagram

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Structured Analysis Method

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  1. Structured Analysis Method Requirements

  2. Structured Analysis Method • Structured system analysis and design (SSAD) • Formal structured dev method • Developed by UK Gov. in the 1980’s • We will focus only on analysis • Was used a lot when automating existing manual systems • Main steps • Draw a context diagram • Draw DFD of the existing system • Draw DFD of the proposed system and identify the man-machine boundary Requirements

  3. SSAD Main steps • Draw a context diagram • Draw DFD of the existing system • Draw DFD of the proposed system and identify the man-machine boundary Context Diagram • The context diagram - represent all external entities that may interact with a system • Is a DFD with one transform (the system), with all inputs, outputs, sources, sinks for the system identified • The highest level view of a system Requirements

  4. Example Context Diagram Requirements

  5. SSAD Main steps • Draw a context diagram • Draw DFD of the existing system • Draw DFD of the proposed system and identify the man-machine boundary DFD of the current system • The current system is modeled as-is as a DFD to understand the working • The context diagram is refined • Each bubble represents a logical transformation of some data • Leveled DFD may be used • Generally obtained after understanding and interaction with users • Validate the DFD by walking through with users Requirements

  6. SSAD Main steps • Draw a context diagram • Draw DFD of the existing system • Draw DFD of the proposed Modeling the Proposed System • No general rules for drawing the DFD of the future system • Use existing system understanding • DFD should model the entire proposed system - process may be automated or manual validate with the user • Then establish man-machine boundary • what processes will be automated and which remains manual • Show clearly interaction between automated and manual processes Requirements

  7. Example – context diagram Requirements

  8. Example – DFD of existing sys Requirements

  9. Example – DFD of proposed system Requirements

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