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22.02.14 - Req. Modelling

Work models help you take the next leab in understandning from knowing the work of individual stakeholders to understandning the fundamental structure of work for a whole stakeholder population

What are requirement models for?​

Requirements Models​

  • Synthesising all the requirements you collected into key requiremnts
  • You start making diagrams that represent how requirements relate
  • Then you have a comprehensive set of intergrated requirements
  • Representaiton of how something works
  • Different representaiton convey different useful benefits
  • Models are selective representations to portray an important aspect

Most important thing​

  1. What do you want to show
  2. Which diagram or model is best for this

Context Diagrams​

Identify number of systems will have to interact with Want to show how all these systems inter-relate

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  • Shows related systems

  • Often part of Non-Functional requirements

  • Defines the boundaries of the system

  • Represent key systems that need to be deployed

  • And the relationship to the other systems

Task Analysis​

  • For identifying sub tasks
  • Still not good for process, nor decision points

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UML Diagrams​

  • Used to be 3 popular approaches to producing models, 1990 got unified then got UML 2 with 13 different diagrams

5 Key diagram tyoes

  • Behaviour Diagrams
    • Use case diagram
    • Activity Diagrams
    • Sequence Diagrams
  • Structure Diagrams
    • Class Diagrams
    • State Diagrams

Activity Diagrams​

  • Used to elaborate workflows for key activities
  • Explains the process, decision points, wait points and parallel points
  • Usually to define one Use Case in more detail
  • May tie together several use cases for one bigger process

Sequence Diagrams​

  • Good for sharing information between people and systems
  • Series of messages between key components
  • Can be used to specify function calls in java

Class Diagrams​

  • Specify the classes in oops code
  • A lot like a Entity relationship diagram, done well, more like a specification

State Diagrams​

  • All the states that something can be in
  • And what actions can change it

Scenarios​

  • Must define a setting or context
  • Must define one or more actors or users
  • Must define goals or objectives
  • Must describe a plot
    • Describes how a user, in a context, achieves a goal
  • Written text descriptions