10-05-2013, 12:22 PM
Requirements Documentation
Requirements.ppt (Size: 229.5 KB / Downloads: 63)
Problems in developing computer based systems since 1960s
Too many systems are late or over budget
Systems don't do what the users really want or never used to the effectiveness
(there are rarely a single reason for these problems but a major contributory factor is difficulties with system requirements)
What are requirements?
A specification of what should be implemented
Defined at early stages of a system development
Include:
how the system should behave
application domain information
constraints on the system's operation
specification of a system property or attribute.
What is requirements engineering?
A relatively new term invented to cover all of the activities involved in discovering, documenting and maintaining a set of requirements for a computer-based system.
Use of the term 'engineering' implies that systematic and repeatable techniques should be used to ensure that system requirements are complete, consistent and relevant.
Common requirements' problems
Don't reflect the real needs of the customers
Inconsistent and incomplete
Expensive to make changes to the requirements after they have been agreed
Misunderstandings between customers, those developing the system requirements and software engineers
What happens when requirements are wrong?
System may be delivered late or with more cost than originally expected
Customer and end-user might not be satisfied with the system
System may be unreliable in use, with regular system crashes happening all the time.
If system continues in use, the costs of maintaining and evolving are usually very high.
Requirements analysis and negotiation
Aim at discovering problems with the system requirements and reach agreement on changes to satisfy all system stakeholders
Requirements are analyzed in detail
Different stakeholders negotiate to decide on which requirements are to be accepted
Since there are inevitably conflicts between the requirements from different sources, information may be incomplete or may be incompatible with the budget available