Summary

An application can be loosely classified as one of:

• Sovereign: large complex apps. Many functions and controls. Used for long periods.
  Examples: word processor, spreadhseet, IDE, presentation app.
• Transient: small apps run for a single task for a short time. Few functions.
  Examples: simple editors (text or graphics), multimedia players (i.e. quicktime viewer).
• Daemonic: daemons that users do not usually see. Accessed via control panel or transient program.
• Parasitic: used for long periods, but performs small and simple task.
  Examples: sound mixer, panel clock, system resource meter, cd player.

Acknowledgements

This article is a summary of the article "Your program's posture" by Alan Cooper, written for the Visual Basic Programmers Journal.

Your program's posture

Cooper classifies applications into four groups, listed above. For each group, Cooper describes the expected behaviour and design guidelines.

When you start to design an application, you are faced with a blank screen. How to fill it? A sensible approach is to copy what has gone before. But with a large number of existing applications, it is important to choose carefully what class of application to copy.

Sovereign

• Not necessarily document-centric (but often so).
• Designers are encouraged to use as much screen real-estate as needed.
• Careful (bland) visual design, as the application will be used for long periods.
• Used by experienced users
• Users are prepared to spend time learning the application.
• Designed for optimal use by experienced users, NOT for use by novices (I think Cooper implies that designing for expert users and novice users simultaneously is not possible, but on this point is at odds with Kevin Mullet and Jef Raskin. I also would like to think that designing a good interface to saisfy both experts and novices is possible).

Transient

• Used for short period.
• Small set of functions with large obvious controls.
• All dialogue boxes are transient programs.
• Often supports sovereign app, and superimposed on transient.

Daemonic

• Do not interact with user.
• Another transient program is needed to configure the daemon. This can be a control-panel program or simply a transient program.

Parasitic

• Continuously present like sovereign.
• Superimposed on another programs like transient programs.
• Often reporters of system information (like xload).
• Examples include: panel/taskbar clock, MS Office manager.