1. Requirements Engineering Lecture 6
Jerzy Nawrocki
Requirements Engineering
Lecture 6
Standard SRS
Copyright, 2000 © Jerzy R. Nawrocki
Requirements Eng., Lecture 6

2. J. Nawrocki, Requirements Eng., Lecture 6
Plan of the lecture
Introduction
Requirements document
Good practices in describing requirements
Use scenarios
J. Nawrocki, Requirements Eng., Lecture 6

3. Computer-based systems
Jerzy Nawrocki
Computer-based systems
Software
Hardware
People
Database
Documentation
Procedures
J. Nawrocki, Requirements Eng., Lecture 6
Requirements Eng., Lecture 6

4. J. Nawrocki, Requirements Eng., Lecture 6
Restraining factors
Assumptions
Simplifications
Limitations
Constraints
Preferences
J. Nawrocki, Requirements Eng., Lecture 6

5. J. Nawrocki, Requirements Eng., Lecture 6
A good SRS
Unambiguous (one interpretation)
Verifiable (one can check that req. are met)
Complete (responses to invalid input)
Consistent (no conflicts between req.)
Modifiable (changes are not a big problem)
Traceable (origin of each req. is clear)
Usable during the Operation and Maintenance Phase
J. Nawrocki, Requirements Eng., Lecture 6

6. Source Documents for Requir’s
SRS
SRS
Ver. n+1
Manual
Ver. n
J. Nawrocki, Requirements Eng., Lecture 6

7. Source Documents for Requir’s
SD4R: Source document for requirements
Types of SD4R:
Video
File Audio
Hard(copy)
Advice:
Try to keep all the
SD4Rs as text files
J. Nawrocki, Requirements Eng., Lecture 6

8. Requirements document (1)
1. Introduction
1.1 Purpose of the document
1.2 Scope of the product
1.3 Definitions, acronyms and
abbreviations
1.4 References
1.5 Overview of the document
J. Nawrocki, Requirements Eng., Lecture 6

9. Requirements document (2)
2. General description
2.1 Product perspective
2.2 Viewpoints
2.2.1 Stakeholders
2.2.2 Users
2.2.3 Domain
2.2.4 Components
2.3 System architecture and use cases in UML
2.4 General constraints
2.5 Assumptions and dependencies
J. Nawrocki, Requirements Eng., Lecture 6

10. Requirements document (3)
3. Technical requirements
3.1 Functional requirements
3.1.1 Requirement 1
Introduction
Viewpoint and source(s)
Firmness and importance
Verifiability and clarity
Inputs
Processing
Outputs
J. Nawrocki, Requirements Eng., Lecture 6

11. Requirements document (4)
. .
3.2 External interface requirements
3.2.1 User interfaces
3.2.2 Hardware interfaces
3.2.3 Software interfaces
3.2.4 Communication interfaces
3.3 Performance requirements
J. Nawrocki, Requirements Eng., Lecture 6

12. Requirements document (5)
3.4 Design constraints
3.4.1 Standards compliance
3.4.2 Hardware limitations
. . .
3.5 Attributes
3.5.1 Security
3.5.2 Maintainability
J. Nawrocki, Requirements Eng., Lecture 6

13. Requirements document (6)
3.6 Other requirements
3.6.1 Database
3.6.2 Operations
3.6.3 Site adaptation
3.6.4 Training
. . .
3.7 Non-technical requirements
Appendixes
Index
J. Nawrocki, Requirements Eng., Lecture 6

14. Davis’ Principles for RE
Understand the problem before you begin to create the analysis model
Develop prototypes showing how the human-machine interaction will occur
Record the origin of and the reason for every requirement
Use multiple views of requirements (data, functional, and behavioural)
Prioritise requirements
Work to eliminate ambiguity
J. Nawrocki, Requirements Eng., Lecture 6

15. J. Nawrocki, Requirements Eng., Lecture 6
Jerzy Nawrocki
Further readings
IEEE Guide to Software Requirements specification, ANSI/IEEE Standard
I. Sommerville, P. Sawyer, Requirements Engineering, John Wiley & Sons, Chichester, 1997 
J. Nawrocki, Requirements Eng., Lecture 6
Requirements Eng., Lecture 6

16. J. Nawrocki, Requirements Eng., Lecture 6
Jerzy Nawrocki
Homework
Write SRS for a personal library system.
J. Nawrocki, Requirements Eng., Lecture 6
Requirements Eng., Lecture 6

17. J. Nawrocki, Requirements Eng., Lecture 6
Quality assessment
1. What is your general impression? (1 - 6)
2. Was it too slow or too fast?
3. What important did you learn during the lecture?
4. What to improve and how?
J. Nawrocki, Requirements Eng., Lecture 6