Pattern Templates

According to Christopher Alexander, "Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice."

I think the value of patterns is two key things:
1. Concise solution descriptions
2. A common vocabulary

I also think the best way to think about patterns is that they are a simple way to share strategies and principles.  By naming them, you give them a simple handle.

Recently, a colleague asked me for a simple pattern template, and I didn’t have anything to just point to, so I did a quick roundup of some examples.

Pattern Templates
Here are example pattern schemas and pattern templates from a few key sources:

Source	Template
C2.com	Name Context Problem Forces Solution Resulting Context Known Uses Example Related Patterns
Enterprise Solution Patterns	Context Problem Forces Solution Example Resulting Context Benefits Liabilities Related Patterns
Patterns for Enterprise Solution Architecture	Name Intent Sketch Motivating Problem How It Works When to Use It Further Reading
Prescriptive Guidance	Title Context Problem Forces Solution Considerations Additional Resources Related Items
Real-Time Design Patterns	Abstract Problem Pattern Structure Collaboration Roles Consequences Implementation Strategies Related Patterns Sample Model
Web Services security Patterns	Context Problem Forces Solution Resulting Context Extensions
Windows Azure Design Patterns	Problem Solution Analysis Example Related Patterns

Sample Patterns

Source	Sample
C2.com	Component Bus
Enterprise Solution Patterns	Three-layered Services Application
Web Services security Patterns	Trusted Subsystem Pattern
Windows Azure Design Patterns	Hosted Service

Pattlets
Pattlets were used in Enterprise Solution Patterns to briefly summarize a pattern, without fully documenting it.  Here are a few samples:

Item	Description
Abstract Factory	Provides an interface for creating families of dependent objects without specifying their concrete classes.
Application Controller	Is a centralized point for handing screen navigation and the flow of an application.
Facade	Provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.

A page of pattlets is available on MSDN.

Key Links

• C2.com
• Enterprise Solution Patterns
• Prescriptive Guidance Engineering
• Web Services Security Patterns
• Windows Azure Design Pattern Catalog