Requirement Elicitation

1. How the system should react/behave to particular inputs/situations

Nota:

• Constraints on the services offered by the system

1. Constraints on the services offered by the system
2. Often refer to whole system and are more critical

1. 1. Application domain understanding

   Nota:

   • Discussing with the client what they want
2. 2. Requirements collection and classification

   Nota:

   • Sorting requirements into coherent groups
3. 3. Conflict resolution

   Nota:

   • different demands from user, system safety vs availability, data security vs accessability
4. 5. Prioritsation
5. 4. Requirements checking
   1. verifiability

      Nota:

      • Have measures been specified against which success can be judged
   2. consistency

      Nota:

      • Are there any inconsistencies or conflicts among requirements?
   3. realism

      Nota:

      • Is it feasible to rsatisfy requirements given limitations in technology & budget?
   4. Validity

      Nota:

      • Do all perceived requirements solve real problems?
   5. for Completeness

      Nota:

      • Have we captured all requirements?

1. Diagrams

   Nota:

   • Formality and rigour - Strict notations in symbols have particular meaning and enforce precise descriptions diagramming is a design excersise - better understanding of the problem system views at different levels of abstraction - diagrams can show high-level views of a system as well as detailed views effective representation of architecture and behaviour: Diagrams can show both structure/composition and behaviour  
   1. View Points

      Nota:

      • View Points provide a multi-prespective analysis of requirements from different classes of users that have a different role in the usage of a system
   2. Use case Diagrams

      Nota:

      • Use case diagrimes identify use cases and use cases describe detailed scenarios of operation showing main and alternative flow of events
   3. State Machines

      Nota:

      • State Machines can show how the state of a system or an object within changes in response to events generated by users and the enviroment. they can capture requirements as well as describe the design of a system.
2. pseudocode

   Nota:

   • Pseudocode uses a combination of concepts of a programming language and free text to describe things rather than strictly defined program entitites
3. natural language

   Nota:

   • Normal language, people can understand and is expressive.. but can be imprecise without long sentences & paragraphs which make documents hard to read. Relationships are difficult to record and see in such documents.