ObjectOriented Systems Development: Survey of Structured Method

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Object-Oriented Systems Development Survey of
Structured Method

• By A.G. Sutcliffe, 1991
• Presented by Xiang Kong

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Summary

• OOD vs. Traditional Structured Methods
• How Structured Methods support OO Concept.

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Outline

• Object-Oriented Concepts
• Modeling Components
• Structured Method Evaluation Procedure
• Object-Oriented Methods
• Structured Methods
• Review of Object Orientedness of System
  Development Methods
• Conclusions

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Object-Oriented Concepts

• Three principles that make OOD to improve
  software design for reliability and maintenance.
• Abstraction Objects are an abstraction of parts
  of real-world. More maintainable and reusable.
• Encapsulation Objects hide their internal
  contents from other components to improve
  maintainability.
• Inheritance By organizing objects in class
  hierarchies to promote reuse.

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Modeling Components

• Objects vs. Traditional Concepts of Entities and
  Functions
• Objects are close to entity concept. I.e. a
  collection of attributes, objects add activities
  to entity.
• Objects are a type with one or more instances of
  type, same as entity-type concept
• Objects instances may be changed by events and
  record state changes

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Structured Method Evaluation Procedure

• Conceptual modeling
• The data and processing control parts of a system
  are modeled in one unit rather than separately
• The method produces model of objects
  communicating by messages
• Models object types and instances
• Classification of objects is supported with
  property inheritance.

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• Procedure and guidance
• The method should guide the analyst towards
  identifying and describing objects.
• Guidance should be available for analysis,
  specification and design phases.
• Transformations and products
• Design transformation should support change of OO
  specifications into designs implementable in OOP
  languages.

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Object-Oriented Methods

• Hierarchical Object-Oriented Design (HOOD)
• The top-down hierarchical decomposition approach.
  HOOD is heavily geared towards an implementation
  in Ada.
• The main process in HOOD is called the Basic
  Design Step. "A Basic Design Step has as its goal
  the identification of child objects of a given
  parent object, and of their individual
  relationships to other existing objects, or the
  refinement of a terminal object to the level of
  the code.
• Object-Oriented System Design (OOSD)
• Object-Oriented Systems Analysis (OOSA)
• Object-Oriented Analysis (OOA)
• ObjectOry

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R-A-S-D-I Requirements, Analysis, Specification,
Design and Implementations Feature analysis of
Object-Oriented methods
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Structured Methods

• Structure System Analysis and Design Method
  (SSADM)
• Standard structured method used for UK government
  projects
• Data-driven, 6 stages
• Analysis system operation and current problems
• Specification of requirements
• Selection of technical options
• Logical data design
• Logical process design
• Physical design

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• Information Engineering (IE)
• Encourage data modeling
• Functional specification uses process dependency
  and action diagram, separated from data modeling
• Information System Activity and Change Analysis
  (ISAC)
• Structure Analysis/Structured Design (SASD)
• Structured Analysis and Design Technique (SADT)
• Jackson System Development (JSD)
• Nijssens Information Analysis Method (NIAM)
• Mascot-3

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IS Information System, RT real-time Summary of
method specification models and approaches
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Review of Object Orientedness of System
Development Methods
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Conclusions

• Use of a particular system development method
  will bias implementation of OO systems, OO design
  may not derived from any specification.
• Data model and OO specification show considerable
  convergence. It is feasible to migrate from
  structured method such as JSD, IE and SSADM to OO
  Method.
• Functionally based development methods are less
  well suited to development of OO system.
• OO methods have yet proven in practice, they have
  little CASE tool support, lack of modeling
  techniques for reuse system development.

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References

• A Survey of Object-Oriented Methods by Peter
  Biggs, University of Durham, ACM
• Structured system analysis and design method
  (SSADM) by Caroline M Ashworth, 1998 Information
  and Software Technology.

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Question?