Software Engineering Data Flow Models

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Software Engineering Data Flow Models

• Sommerville, Ian (2001)
• Software Engineering,
• 6th edition Chapter 7
• http//www.software-engin.com

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Analyses and design of IS

• Basic techniques
• Process orientation (processes, activities,
  functions)
• Data orientation (data, entities, objects)

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Data-processing models

• Data flow diagrams are used to model the systems
  data processing
• These show the processing steps as data flows
  through a system
• Intrinsic part of many analysis methods
• Simple and intuitive notation that customers can
  understand
• Show end-to-end processing of data

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Order processing DFD
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Equipment procurement process
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Data flow diagrams

• DFDs model the system from a functional
  perspective
• Tracking and documenting how the data associated
  with a process is helpful to develop an overall
  understanding of the system
• Data flow diagrams may also be used in showing
  the data exchange between a system and other
  systems in its environment

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Process models

• Process models show the overall process and the
  processes that are supported by the system
• Data flow models may be used to show the
  processes and the flow of information from one
  process to another

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Example process modelling IDEF0
/activityblock
control
output
input
mechanism / means
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Make client brief
client brief
Make a design
Demand for a design and offer on behalf of a house
design
Submit an offer
offer
project manager / client/ computer system
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Key point

• Data-flow diagrams may be used to model the data
  processing carried out by a system. The system is
  modelled as a set of data transformations with
  functions acting on the data.