Approaches to software development

# Design

During design, your goal will be to decide how the expected functionality is to be allocated to each part of the system. You need to make choices about which classes the system operations should be allocated to. These decisions can be explored and documented using further behaviour models. UML uses interaction (sequence and communication) diagrams that show a set of classes and the messages between them.

During design both structural and behaviour models are elaborated. In fact you will see that behaviour models are used for both external and internal behaviour of objects.

Some artefacts involved in design are shown in Figure 11.

## Activity 16 Analysis and design

Allow approximately 15 minutes.

1. What is the purpose of analysis?
2. What is the purpose of design?
3. What is the role of each of the artefacts produced during design?

## Answer

1. Analysis starts modelling the structure and behaviour of a software solution from a user’s perspective.
2. Design is concerned with making decisions concerning how a system will meet its specification.
3. During design you produce the following artefacts:
   - structural model, an updated version of the one produced during analysis but with its operations specified
   - behavioural models, showing how objects in the system will interact and behave internally, and also how functionality will be distributed across the system.

OpenLearn - Approaches to software development
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