Requirements Modelling and Specification for Service Oriented Architecture

3.2. Classic Requirements versus Use Cases

The use case approach was developed by Ivar Jacobson at Ericsson in the context of his Objectory method, which emerged in an object-oriented form in the 1990s. Subsequently it was absorbed into the Unified Modelling Language (UML), which was then adopted as an OMG standard.

3.2.1. UML Basics

UML is a language for describing models of software artifacts and their designs. A model is a representation of something that differs from the thing itself and is (usually) simpler than the original. There are many kinds of model: iconic models (e.g. in architecture, wind tunnels, fine art, etc.); graphical models (e.g. in UML); simulation models (digital and analogue models of traffic flow, say); textual models (e.g. classic requirements models); prototypes; mathematical models (e.g. designing a car engine, getting to the moon, etc.); axiomatic (realization) models. Some models fall into more than one of these categories.

Specifically, the models of UML are meant to be based on the object metaphor. Object modelling has its roots in simulation modelling (cf. Graham, 2001) and is the foundation for use-cased-based specifications. UML models should be easy to understand for both analysts and users, but only if done well. UML is certainly useful in allowing developers to communicate among themselves, either using documents or at the whiteboard. Its models record what objects there are and how they are related, what tasks they can perform and how they ...