Table of Contents
1. Definition 2. Information Description or System Model 3. Functional Description 4. Requirements Validation 5. Ten Tips for Getting Useful Information from Users 6. Characteristics of a Software Requirements Specification 1. Unambiguous 2. Complete 3. Verifiable 4. Consistent 5. Modifiable 6. Traceable 7. Usable during the operation and maintenance phase 7. Rules of Order for Specifying SW Requirements 8. The Seven Sins of the Specifier 1. A Case Study 9. Sample Document Outline 10. A Little Humour!
• a set of precisely stated properties or constraints which a software system must satisfy. • a software requirements document establishes boundaries on the solution space of the problem of developing a useful software system.
A software requirements document allows a design to be validated - if the constraints and properties specified in the document are satisfied by the software design, then that design is an acceptable solution to the problem.
The task should not be underestimated, e.g. the requirements document for a ballistic missile defence system (1977) contained over 8000 distinct requirements and support paragraphs and was 2500 pages in length.
Six requirements which a software requirements document should satisfy according to Heninger (1980): 1. it should specify only external system behaviour, 2. it should specify constraints on the implementation, 3. it should be easy to change, 4. it should serve as a reference tool for system maintainers, 5. it should record forethought about the life cycle of the system, and 6. it should characterize acceptable responses to undesired events.
Information Description or System Model
This conceptual model is a very high-level view of the system in which the major user services are identified
Bibliography: 1. references to all documents that relate to the software. 3. Appendix 1. information that supplements the specification.