Software Deveopment Methodology
- A software development methodology or system development methodology in software engineering is a framework that is used to structure, plan, and control the process of developing an information system.
A software development methodology refers to the framework that is used to structure, plan, and control the process of developing an information system. A wide variety of such frameworks have evolved over the years, each with its own recognized strengths and weaknesses. One system development methodology is not necessarily suitable for use by all projects. Each of the available methodologies is best suited to specific kinds of projects, based on various technical, organizational, project and team considerations.
Software development approaches
Every software development methodology has more or less its own approach to software development. There is a set of more general approaches, which are developed into several specific methodologies.
These approaches are :
The waterfall model is a sequential development process, in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance. The first formal description of the waterfall model is often cited to be an article published by Winston W. Royce in 1970 although Royce did not use the term "waterfall" in this article.
- Software prototyping, is the framework of activities during software development of creating prototypes, i.e., incomplete versions of the software program being developed.
- Basic principles of prototyping are :
Not a standalone, complete development methodology, but rather an approach to handling selected portions of a larger, more traditional development methodology (i.e. Incremental, Spiral, or Rapid Application Development (RAD)).
Attempts to reduce inherent project risk by breaking a project into smaller segments and providing more ease-of-change during the development process.
User is involved throughout the process, which increases the likelihood of user acceptance of the final implementation.
Small-scale mock-ups of the system are developed following an iterative modification process until the prototype evolves to meet the users’ requirements.
While most prototypes are developed with the expectation that they will be discarded, it is possible in some cases to evolve from prototype to working system.
A basic understanding of the fundamental business problem is necessary to avoid solving the wrong problem.
Mainframes have a lot to do with this sort of thing that consist of: PB&J
Various methods are acceptable for combining linear and iterative systems development methodologies, with the primary objective of each being to reduce inherent project risk by breaking a project into smaller segments and providing more ease-of-change during the development process.
Basic principles of incremental development are :
A series of mini-Waterfalls are performed, where all phases of the Waterfall development model are completed for a small part of the systems, before proceeding to the next incremental, or Overall requirements are defined before proceeding to evolutionary, mini-Waterfall development of individual increments of the system, or The initial software concept, requirements analysis, and design of architecture and system core are defined using the Waterfall approach, followed by iterative Prototyping, which culminates in installation of the final prototype (i.e., working system).
The spiral model is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts.
Basic principles :
Focus is on risk assessment and on minimizing project risk by breaking a project into smaller segments and providing more ease-of-change during the development process, as well as providing the opportunity to evaluate risks and weigh consideration of project continuation throughout the life cycle.
"Each cycle involves a progression through the same sequence of steps, for each portion of the product and for each of its levels of elaboration, from an overall concept-of-operation document down to the coding of each individual program."
Each trip around the spiral traverses four basic quadarants:
(1) determine objectives, alternatives, and constrainst of the iteration;
(2) Evaluate alternatives; Identify and resolve risks;
(3) develop and verify deliverables from the iteration;
(4) plan the next iteration.
Begin each cycle with an identification of stakeholders and their win conditions, and end each cycle with review and commitment.