Design Pattern Classification

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Design Pattern Classification
A Novel Approach

• Vandana Bajaj
• Advisor Prof. Aaron Cass
• 05/06/05

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Background
Think of sewing

• Have vision in mind
• Check pattern catalogue
• Try to find a match

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Background (contd)

• How does a sewing pattern help you?

• What pieces you need
• Allowable design variations
• How to arrange the pieces together
• How to attach the pieces together

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Software design patterns
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Gamma et al. classification

• Purpose
• Structural
• Behavioral
• Creational
• Scope
• Class relationships
• Object relationships

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Design difficulties with GoF

• Have I found the right pattern?
• What parts does the pattern require? What does
  it require beyond the big parts?
• Explore other modes of classification?

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Existing approaches examined

• Erich Gamma et al. (aka Gang-of-Four) Design
  Patterns, 1993.
• Walter Tichy Essential Software Design Patterns
• Frank Buschmann et al. A System of Patterns,
  1996.
• Walter Zimmer Relationships between design
  patterns, 1993.

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Buschmann
Patterns
Problems
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Zimmer

• Relationships
• X uses Y in its solution
• X is similar to Y
• X can be combined with Y
• Layers
• Basic design patterns techniques
• Design patterns for typical software problems
• Design patterns specific to an application domain

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Shortcomings of these

• Vague descriptions
• Little or no consideration past birds eye view
• Unclear mode of classification
• Picking a pattern is still difficult

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Our classification scheme

• Considers kinds of additional detail needed
• Uses formalized constraints
• Related to Buschmann and Zimmer
• A hierarchy

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Our hierarchy
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Advantages of our scheme

• Thorough consideration of constraints
• Greater understanding of patterns
• Easier maintenance of scheme and its hierarchy
• Formalization improves pattern selection?...

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Q A

• ?