Software Process Model

In contrast to software life cycle models, software process models often represent a networked sequence of activities, objects, transformations, and events that embody strategies for accomplishing software evolution. Such models can be used to develop more precise and formalized descriptions of software life cycle activities. Their power emerges from their utilization of a sufficiently rich notation, syntax, or semantics, often suitable for computational processing.

Software process networks can be viewed as representing multiple interconnected task chains. Task chains represent a non-linear sequence of actions that structure and transform available computational objects (resources) into intermediate or finished products.

Non-linearity implies that the sequence of actions may be non-deterministic, iterative, accommodate multiple/parallel alternatives, as well as partially ordered to account for incremental progress. Task actions in turn can be viewed a non-linear sequences of primitive actions which denote atomic units of computing work, such as a user’s selection of a command or menu entry using a mouse or keyboard. Winograd and others have referred to these units of cooperative work between people and computers as “structured discourses of work” (Winograd 1986), while task chains have become popularized under the name of “workflow” (Bolcer 1998).

Task chains can be employed to characterize either prescriptive or descriptive action sequences. Prescriptive task chains are idealized plans of what actions should be accomplished, and in what order. For example, a task chain for the activity of object-oriented software design might include the following task actions:

• Develop an informal narrative specification of the system.
• Identify the objects and their attributes.
• Identify the operations on the objects.
• Identify the interfaces between objects, attributes, or operations.
• Implement the operations.

Clearly, this sequence of actions could entail multiple iterations and non-procedural primitive action invocations in the course of incrementally progressing toward an object-oriented software design.

A typical software process model covers the whole of the life cycle and clearly defines each phase and the tasks and activities to be performed within that phase as well as those activities that are continuous throughout the life cycle.

References:

http://www.ics.uci.edu

http://ipt.web.cern.ch/

Encyclopedia of Software Engineering, 2nd Edition, John Wiley and Sons, Inc, New York, December 2001.