Software Engineering - Old Questions

2. Explain the software process model with example.

A software process model is an abstract representation of a process that presents a description of a process from some particular perspective. Process models may contain activities, which are part of the software process, software product, and the roles of people involved in software engineering. Some examples of the types of software process models that may be produced are:

1. A workflow model: This shows the series of activities in the process along with their inputs, outputs and dependencies. The activities in this model perform human actions.
2. 2. A dataflow or activity model: This represents the process as a set of activities, each of which carries out some data transformations. It shows how the input to the process, such as a specification is converted to an output such as a design. The activities here may be at a lower level than activities in a workflow model. They may perform transformations carried out by people or by computers.
3. 3. A role/action model: This means the roles of the people involved in the software process and the activities for which they are responsible.

There are several various general models or paradigms of software development:

1. The waterfall approach: This takes the above activities and produces them as separate process phases such as requirements specification, software design, implementation, testing, and so on. After each stage is defined, it is "signed off" and development goes onto the following stage.
2. Evolutionary development: This method interleaves the activities of specification, development, and validation. An initial system is rapidly developed from a very abstract specification.
3. Formal transformation: This method is based on producing a formal mathematical system specification and transforming this specification, using mathematical methods to a program. These transformations are 'correctness preserving.' This means that you can be sure that the developed programs meet its specification.
4. System assembly from reusable components: This method assumes the parts of the system already exist. The system development process target on integrating these parts rather than developing them from scratch.