Applying Design Principles in Practice

Nick Rozanski, Chris Cooper Bland, Eoin Woods

PLEASE NOTE - slight change to subject and location!

PLEASE NOTE - drinks reception hosted by Onalytica!

Design principles are generally applicable design rules that, when followed, result in desirable qualities in the design of software. In contrast to patterns, design principles don't provide concrete solutions to specific problems but rather are general guidelines that designers should be aware of when creating their designs. While design patterns are a practical embodiment of good design principles, we observe that many designers using patterns don't seem to understand the principles that make them work well. Examples of design principles are "maximise cohesion", "minimise coupling", "liskov substitutability principle", "don't repeat yourself/minimise duplication", ...

In this session, we will examine a specific set of design principles for distributed information systems that the presenters will provide. We'll examine the set from two directions, initially by applying them to specific, contrasting, design problems to see how they influence the design decisions made, how useful they are, and what is missing from the set. Then from the opposite direction, participants will explore how to relate the design principles back to higher level business goals and technical principles, so aligning the design with the system's wider environment. (This latter technique is enormously useful as a practical way of justifying hard-to-explain and possibly expensive design decisions to senior management.)

This process will allow us to analyse, understand and validate the set of proposed design principles, while also gaining experience in applying and justifying design principles to realistic scenarios.

18:00                Welcome and IASA update

18:30                Design Principles in Practice

19:30                Pizza delivered by Microsoft

20:00                Design Principles in Practice cont'd