my_digital_garden/4a1s/RAS/T - Aula 3.md

26 de Setembro 2023 - #RAS

Definition of Requirements Engineering

• Requirements engineering designates all the activities related to requirements discovery, negotiation, documentation, and maintenance.
• Alternative designation: analysis

[!hint]+ Zave, 1997 Requirements engineering, in the scope of software engineering, is focused on the real-world objectives established for the functionalities and the restrictions of software systems.

Requirements engineering seeks to ensure the three following objectives:

1. all the relevant requirements are explicitly known and comprehended at the intended level of detail;
2. a reasonable and wide agreement about the requirements is obtained among the stakeholders;
3. all the requirements are duly documented, in conformity with the established formats and templates.

[!info] Requirements engineering determines what the system must do to meet the necessities of users and not how it should be built.

[!info] It is desirable keeping the requirements strictly separated from their own solutions.

[!hint] The requirements of a given system are necessary, clear, correct, complete, viable, traceable, verifiable and negotiable.

Activities

Process Scheme: process.excalidraw

1. Inception

• Initiation of the process, based on some necessity or business expectation.
• At the end, the requirements engineer should be able to describe what is the client vision and return on investment.
• One must also evaluate if what the client needs is already available in the market.

2. Elicitation

• This activity handles how requirements should be captured.
• The requirements elicitation techniques must:
  1. identify the sources of requirements;
  2. aid the various stakeholders to correctly describe the requirements;
• This activity is inherently communicational, since it requires an in-depth interaction with the stakeholders.
• Requirements elicitation techniques:
  1. Interview
  2. Survey
  3. Introspection
  4. Ethnography
  5. focus group
  6. cooperative work
  7. domain analysis
  8. object-orientation
  9. prototyping
  10. scenario
  11. goal modelling
  12. persona

3. Elaboration

• This activity aims to analyse and classify the elicited, but not yet handled, requirements.
• Organises the requirements in cohesive groups.
• The analyst must intervene, whenever the requirements: do not make sense; are in contradiction among them; are incoherent; are incomplete; are vague.

4. Negotiation

• Requirements engineering involves communication and negotiation among various stakeholders.
• It is inevitable that conflict situations arise among the requirements. One needs to promote negotiation mechanisms among the stakeholders. Its result can have a significant impact on the acceptance of the final system.
• Another form of handling conflicts consists in adopting prioritisation techniques, to sustain the choice of the requirements subset to be implemented at each instant.

5. Documentation

• Requirements documents serve as the principal reference to the subsequent phases of the development process.