| functional requirement | has definition A requirement that describes a service provided by a system |  |
| describes what the system should do, i.e. the services provided for the users and for other systems | |
| is a subtopic of 4.5 - Types of Requirements | |
| is a kind of requirement | |
| should be consistent with non-functional requirements | |
| should be consistent with project plan | |
| requirement | can be gathered from various stakeholders, other software systems and any documentation that might be available | |
| changes regularly | |
| has part problem statement | |
| indicates how the system is to behave | |
| is expressed as a fact | |
| is grouped with other requirements into a requirements document | |
| is normally expressed in a natural language such as English (using present tense and active voice), sometimes supplemented by a formal mathematical language, and often by some form of diagram | |
| may be given a unique number for traceability | |
| may be shown as a diagram | |
| must be agreed upon by all stakeholders | |
| should be analysed if there is any doubt whether it is realistic | |
| should be changed whenever the benefits of doing so outweigh the costs | |
| should be cut if cost-benefit analysis shows that it will have minimum benefit but still cost a lot to develop | |
| should be expressed using clear and consistent notation, using language that the customers can understand, and consistent with the other requirements | |
| should have benefits that outweigh the costs of development | |
| should help solve a customer's problem | |
| should lead to a system of sufficient quality - one that is sufficiently usable, safe, efficient, reliable and maintainable | |
| should not indicate how it will be implemented in order to give the designer as much freedom as possible to make decisions | |
| should not over-constrain the design of the system | |
Object Oriented Software Engineering View all facts Glossary Help
