B345 Internet Science and Technology 
Week 7 lecture 2

Today's Lecture Learning Objective
- Understand the concept of Patterns.
- Look at example software patterns.
- Relate patterns to software methodologies.

A noteÉ
- About changes to topic reading 6.

Reusable solutions for recurring problems
- In software development
    - Software libraries
    - Example code
    - Algorithms
- Are they effective? What's missing?

Introducing Patterns
- What are patterns?
- Types of patterns.

Urban Planning and Building Architecture
- From the writings of Christopher Alexander:
    - The Quality (or the QWAN)
    - The Gate
    - The Way

Elements of Patterns
- Name
- Problem
- Context
- Forces
- Solution
- Examples
- Resulting Context
- Rationale
- Related Patterns
- Known Uses

Patterns and Algorithms
- Are they the same thing?

Issues of Patterns
- Generative patterns.
- Anti-patterns. 
- Piecemeal growth.
- Pattern languages.
- Pattern mining.

Example Patterns
- From www.patterndepot.com 
    - www.patterndepot.com/put/12/parsepat.html

Contribution in Development Methodologies
- Reusability.
- Understanding of context.
- Formulating architectures with patterns and pattern languages.

Pattern Development
- Is a particular development methodology founded on using patterns?

Guides to Writing Patterns
- Look for example patterns already defined. 
- Look for patterns in existing software (pattern mining).
- Pick solutions proven to be useful in definite contexts. Know why that solution exists in the first place.
- Pick a format to write it in.
- Circulate for feedback. Submit for reviews.
- Iterate and refine.