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7.2 design



Why do we need the design phase?

Before you start developing a system you need a plan of action, together with design ideas for each of the areas of the system. Spending a good amount of time designing a system in advance will allow you and the rest of the development team the ability to solve problems in advance of the development, saving a considerable amount of time and money. It may also highlight issues that need to addressed before the project can move ahead.

What things need designing?

  • Form and Input Screen Designs
  • Report and Output Screen Designs
  • Input validation the needs to performed on data.
  • Data Structures that need to be created


User Documentation

User documentation is required to assist the user in using the system. The documentation can be paper or electronic based and can include:

  • Training Manuals
  • Operating procedures to be followed when using the system.
  • Video tutorials

Technical Documentation

Technical documentation is designed to help maintain and upgrade the system.

Technical documentation may include:

  • Software documentation, indicating the names and purpose of functions in the code.
  • A system map, showing how all the different parts of the system fit together.
  • Data validation and the validation ranges for different data.

Engineers or system administrators will refer to this documentation when they are looking at the system.


Screens, Forms & Input

Screen Design

In your exam you will likely be asked to design a screen input form.

In order to succeed you need to ensure that you include:

  • A screen title
  • Appropriate inputs & labels
  • Appropriate annotations explaining the purpose of each and any validation required.
  • A submit button

It should also:

  • Be sensibly laid out
  • Use the full area of the screen appropriately


Data Validation

There are three types of data that may be entered in to a system:

Valid Data

  • This is data that fits comfortably within the acceptable data range (Age input: 25)
  • In this instance the system would normally accept the data without further question.

Extreme Data

  • This is data that sits at the very edge of acceptable data. ( Age input : 0 or 110)
  • In this instance the system should normal prompt for the user to double check the data (Are you sure….)

Invalid Data

  • This is data that is outside acceptable data range (Age input: -45  or 20000 )
  • In this instance the system should reject the data, requiring the user to input a valid answer.

Reports and outputs

Data Structures