Monday, 24 June 2002
How to create a screen design? There is sufficient information on gui design principles, but how does functional design work in practice?

Screen design is similar to modelling clay:

  1. It is a creative process.
  2. The result is unpredictable.
  3. Every descision is reversable.
Especially the last point is important. No single design descision is final. The designer can try out things, create a number of versions, continue working till the result satisfies.

The process looks a bit chaotic. Yet there is some structure, roughly divided into two possible approaches.

1. Inside out

For small systems the designer can start working with the user. The desired functionality rapidly gets clear in a number of sketch and test sessions.

As soon as the exterior of the system is stable, the designer can start analysing the inside of the system. The data elements on the sketches are input for the unnormalised form.

2. Inside out

For complex systems it is better to first have a look at the structure of the system.
  1. Use data analysis mehtods to create a conceptual model and a Crud matrix.
  2. Start looking at identifying relations, created during the second normal form.

    Most likely the Crud matrix has a function with a C (Create) for both entities. Start designing those functions. The one entity will populate the top of the screen, the many will map to a list below.

  3. Next, look at other relations, created during third normal form. A foreign key has only one value at the time. Choose the right widgets for such a single choice in update screens.
  4. A many-to-one relation is a good candidate for a hyperlink to a higher level.
  5. One-to-many relations are good candidates for a list with hyperlinks to a lower level.
Till next week,