Subsections
This section shows how to trace the results of your analysis and design work back to your user requirements.
Upon completion of this section, students will be able to:
- Define a requirement
- Describe the nature of requirements, use cases, and functions
- A user-specified criterion that the system must satisfy.
- Requirements define the bahvior and functionality of a proposed system.
- Usually expressed as sentences that include the word shall or must.
- Functional - ``The system shall automatically generate postings to the general ledger''.
- Data - ``The system ... international currencies ...''.
- Performance - ``The system must ... in XX seconds''.
- Capacity - ``Up to 10,000 transactions per day''.
- Test - ``Stress testing shall ... XX users ... YY computers ...''.
- A use case describes a unit of behavior.
- A requirement describes a law that governs behavior.
- Several types of requirements: functional, performance, and constraints.
- A use case can satisfy one or more functional requirements.
- A functional requirement may be satisfied by one or more use cases.
- Requirements are requirements, use cases are use cases. Requirements are not use cases.
- Make a list of the system requirements.
- Write the user manual for the system in the form of use cases.
- Iterate with your customers until you have closure of items 1 and 2.
- Make sure you can trace every piece of your design to at least one user requirement.
- Make sure you can trace every requirement to the point at which its satisfied within your design.
- Trace your design back to your requirements as you review the design during your critical design review.
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