1. Requirements Engineering
Jarosław Kuchta
Embedded Systems Software Engineering
Requirements Engineering
GUT - INTEL 2015/16
Embedded Systems Software Engineering

2. Main objectives of requirements engineering
To help a customer to become aware of the requirements
To discover implicit requirements
To precise requirements’ specification
To set up a basis for planning (budget and schedule)
To set up a foundation for developers’ word
To enable control of development process
I know you think you understand what you think I said, but I’m not sure you realize that what you heard is not what I thought...
GUT - INTEL 2015/16
Embedded Systems Software Engineering

3. Three kinds of requirements
Well known by the customer and explicitly enumerated
Well known by the customer but not explicitly enumerated and not realized by the developers
Not realized by the customer but implicitly required by standards or legislation to achieve good product quality
GUT - INTEL 2015/16
Embedded Systems Software Engineering

4. Embedded Systems Software Engineering
Main activities
Requirements sources identification
Project objectives recognition (business and functional)
Project context and range recognition
Functional requirements extraction
Non-functional requirements elicitation (data requirements, quality requirements etc.)
Agreement on rules for product acceptance
Collect data for analysis and design
GUT - INTEL 2015/16
Embedded Systems Software Engineering

5. Embedded Systems Software Engineering
Requirements sources
Stakeholders (personal sources):
Customers / management (business goals)
End users (functional requirements)
Other people (stuff, community)
Non personal sources:
Legislation
Formal and informal standards
GUT - INTEL 2015/16
Embedded Systems Software Engineering

6. Embedded Systems Software Engineering
Project objectives
Business goals
What are the benefits for the customers and/or users of the planned system?
Functional purposes
What are the main functions of the system to help customers and/or users to achieve business goals?
GUT - INTEL 2015/16
Embedded Systems Software Engineering

7. Software system context
What are the main system components?
Which components should be implemented in the software system?
What functional purposes should be realized in each component?
Software system
Data
Documentation
Hardware
Organization
Procedures
People
GUT - INTEL 2015/16
Embedded Systems Software Engineering

8. Requirements description
Text description
Diagrams
Mathematical / physical formulas
Combined description (consistency problem)
The need for logical organization and relationships requirements - reveals gaps, redundancies and inconsistencies in the requirements
The requirements of different stakeholders are recorded separately and then merged together
Requirements must be numbered so that in later phases the developers will be able to refer to them.
GUT - INTEL 2015/16
Embedded Systems Software Engineering

9. System Requirements Specification
Introduction
Basic Info
Functional Requirements
Non-functional Requirements
Acceptation Criteria
References
Appendices
GUT - INTEL 2015/16
Embedded Systems Software Engineering

10. Embedded Systems Software Engineering
Basic Info (1)
Requirements Sources (stakeholders and other)
Project Objectives (determined by customers and/or users)
Business Goals – determined by customers (management)
Functional Purposes – determined by end users)
Note: Sources and objectives are prioritized to set up their importance and implementation order
GUT - INTEL 2015/16
Embedded Systems Software Engineering

11. Embedded Systems Software Engineering
Basic Info(2)
System Context
Users (roles)
External Systems
Infrastructure conception (for complex systems)
Subsystems
Components
GUT - INTEL 2015/16
Embedded Systems Software Engineering

12. Functional Requirements
System function detailed description
Requirements organization (by users / by components)
Requirement properties:
text description
applies to (which user / external system)
source of the requirement
priority
GUT - INTEL 2015/16
Embedded Systems Software Engineering

13. Non-functional Requirements
Data Requirements
Quality Requirements
Other Requirements
GUT - INTEL 2015/16
Embedded Systems Software Engineering

14. Embedded Systems Software Engineering
Data Requirements
Main data concepts
Data terms explanation
Source of explanation
Priority
GUT - INTEL 2015/16
Embedded Systems Software Engineering

15. Embedded Systems Software Engineering
Quality Requirements
Reliability (safety, security, error tolerance)
Performance (execution efficiency, interaction efficiency)
Flexibility (portability, stability, scalability)
Usability (learnability, understandability, operability)
Note: Quality requirements should be precisely determined (quantified)
GUT - INTEL 2015/16
Embedded Systems Software Engineering

16. Embedded Systems Software Engineering
Other Requirements
Extraordinary situations (exceptional situations, critical situations, failover situations)
Hardware configuration requirements
Software configuration requirements
Extra requirements
GUT - INTEL 2015/16
Embedded Systems Software Engineering

17. Embedded Systems Software Engineering
Acceptation criteria
Tests
Trial time
Maintenance
Specific constraints
GUT - INTEL 2015/16
Embedded Systems Software Engineering

18. Embedded Systems Software Engineering
References
“System Vision” document
Technical documentation
Articles
Standards
Existing source code
...
GUT - INTEL 2015/16
Embedded Systems Software Engineering

19. Embedded Systems Software Engineering
Appendices
Glossary (may be in separate document)
Tabular data
Diagrams
...
GUT - INTEL 2015/16
Embedded Systems Software Engineering

20. Embedded Systems Software Engineering
SRS purpose
Basis for estimating and planning
Functional requirements  use cases modeling
Data requirement + glossary  class modeling
Quality requirements, hardware/software configuration  design decisions
Acceptance criteria  test design
GUT - INTEL 2015/16
Embedded Systems Software Engineering

21. Embedded Systems Software Engineering
Bibliography
Roger S. Pressman: Software Engineering. A Practitioner's Approach (book, PDF)
USA Department of Defense: Systems Engineering Fundamentals (PDF)
Klaus Pohl, Chris Rupp: Requirements Engineering Fundamentals (book)
IREB (International Requirements Engineering Board) Downloads
GUT - INTEL 2015/16
Embedded Systems Software Engineering