Software Design: Summary

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Software Design Summary
Andrew Ireland School of Mathematical Computer
Sciences Heriot-Watt University Edinburgh
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Outline

• Nature of Software Design
• Architectural Design
• Function-oriented Design
• Object-oriented Design
• Software Reuse and Component-based Design
• Verification Validation

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Architectural Design

• Systems structuring, i.e. identify the key
  subsystems and the way in which they will
  communicate
• Repository, client-server, layered
• Control modelling, i.e. how is control managed
  between the subsystems?
• Centralized vs event-based
• Subsystem decomposition

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Function-oriented Design

• Transaction based systems, minimal state
• Data flow
• Structure charts
• Detailed design

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Object-oriented Design

• Decentralized state, exploiting information
  hiding and hierarchies
• Many OOD methods, but common ingredients
• Identification of objects CRCs use cases
  grammatical analysis
• Identification of static perspective class
  diagrams
• Identification of dynamic perspective sequence
  communication activity state machine diagrams

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Component-based Design

• Promote software reuse
• Key ingredients
• Well defined service (functionality)
• Well defined interface
• Explicit dependencies
• Standardization (component model), e.g. CORBA,
  EJB, COM (.NET)
• Compositionality trade-offs
• Predictability, trustworthiness certification

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Verification Validation

• Definitions
• Static dynamic analysis
• Analysis testing life-cycle
• Early phase analysis
• Planning for testing
• Exploiting design notations (UML)
• From unit to acceptance testing

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Typical Exam Questions

• Explain concepts and approaches using examples,
  e.g.
• Using an example explain the role of CRCs with
  software design process
• Be able to compare and contrast the relative
  merits of particular approaches, e.g.
• Compare and contrast the trade-offs between
  component-based design vs designing a system from
  scratch.

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Typical Exam Questions

• Given a scenario, be able to propose a software
  architecture together with a justification
• Given a scenario, apply a particular technique or
  approach, e.g. given English requirements
  develop DFDs structure charts use cases CRCs
  class, sequence communication, activity, state
  machine diagrams.
• Alternatively, be able to answer questions on a
  given design OR extend the design OR compare it
  against given requirements