Requirement pattern concepts

04 Jan 2015

“Each pattern describes a problem which occurs over and over again in our environment” - Christopher Alexander

Projects have requirements which are similar in nature
Requirement pattern: An approach for specifying a particular type of requirement
Follow-on requirements: Expand the original requirement
Pervasive requirements: Supports the pattern itself
Patterns can vary on their level of detail (their preciseness)

Benefits of requirement patterns:

Guidance: Suggests information to include, advices, warning of common pitfalls.
Time save: Don’t have to write each requirement from scratch, gives a suitable starting point, a foundation to build on.
Consistency across requirements of the same type

The anatomy of a requirement pattern

What it contains, how it is organized and why
A requirement pattern needs to say when to use it, how to write requirements based on it. Can also give hints on how to implement and how to test it.

To convey these sorts of information, each requirement pattern should contain

Basic details: Pattern classification, author, related patterns, etc
Applicability: In what situations can this pattern be applied?
Discussion: How to write a requirement of this type? What needs to be considered?
Content: What must a requirement of this type say?
Template(s): Starting point for writing a requirement of this type
Example(s): One or more representative examples
Extra requirements: What sorts of requirements often follow on
Considerations for development: Hints for software designers and engineers on how to implement a requirement of this type
Considerations for testing: What do we need to bear in mind when deciding how to test this type of requirement?

For classifying the requirement patterns, instead of having a monolithic list of them, they are usually assigned to a domain
Each domain needs an introduction to explain its theme (features in common to all its patterns)
Some types of requirements depends on infrastructure. They may be added to the pattern through infrastructure overviews.

When requirement patterns have features in common, a pattern group can be created
Pattern groups differ from domains in the sense the domain patterns share a common theme, and the groups have detailed features in common.

A pattern mught refer to other patterns
The relationship can be fundamentally a mention (refers to) or a pattern extension (specialization)