Concurrent Development Model:

The concurrent process model defines a seriesof events that will trigger transition from state to state for each of thesoftware engineering activities. For e.g., during early stages of design, aninconsistency in the analysis model is uncovered. This generates the eventanalysis model correction, which will trigger the analysis activity from the donestate into the awaiting Changes State.

The concurrent process model is often used asthe paradigm for the development of client/server applications. A client/serversystem is composed of a set of functional components. When applied toclient/server, the concurrent process model defines activities in twodimensions a system dimension and component dimension. System level issues areaddressed using three activities, design assembly, and use. The componentdimension addressed with two-activity design and realization. Concurrency isachieved in two ways; (1) System and component activities occur simultaneouslyand can be modeled using the state – oriented approach (2) a typical clientserver application is implemented with many components, each of which can bedesigned and realized concurrently.

The concurrent process model is applicable toall types of software development and provides an accurate picture of thecurrent state of a project. Rather than confining software-engineeringactivities to a sequence of events, it defines a net work of activities. Eachactivity on the network exists simultaneously with other activities. Eventsgenerated within a given activity or at some other place in the activity networktrigger transitions among the sates of an activity.

This model incorporates thecharacteristics of the spiral model. It is evolutionary in nature, demanding aniterative approach to the creation of software. However, the component-baseddevelopment model composes applications from prepackaged software componentscalled classes.