What are Requirements?
The simple definition: it's what you need.
In the software world (Dorfman and Thayer, 1990), requirements are:
a software capability needed by the user to solve a problem to achieve an objective
a software capability that must be met or possessed by a system or system component to satisfy a contract, standard, specification, or other formally imposed documentation.
is a use case?
A Use Case is one several tools or techniques that we will use to capture or document requirements. Other tools are such things as workflow diagrams, data models, flowcharts, etc. The Use Cases will be one part of the complete package of technical documentation that describes our business and system requirements. In our JAD sessions, CGI facilitators will be asking lots of questions about how people do various business functions, such as "how does someone transfer an animal from enclosure to enclosure" to better understand the business process. These discussions will identify how, when, and where a ZIMS user needs to 'interact' with ZIMS. The results of these discussions will be captured for each specific business function in a detailed Use Case.
Case describes scenarios in which an “Actor” (Performer, Documenter, Planner
etc.) interacts with the “SuD” (System Under Discussion - ZIMS /
Organization / Institution). It describes what an “Actor” does and how the
“SuD” reacts. A use case describes a complete course of events. Use Cases
are a key deliverable of the requirements analysis effort.
use case consists of:
cases will be used as a basis for the design of ZIMS, walkthrough's and user
are two types of Use Cases:
Business Use Case:
System Use Case: