Introduction to Software Engineering Methodology

The Waterfall model is a sequential development approach, 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 method is often cited as an article published by Winston W. Royce in 1970 although Royce did not use the term "waterfall" in this article.

The basic principles are:

• Project is divided into sequential phases, with some overlap and splashback acceptable between phases.
• Emphasis is on planning, time schedules, target dates, budgets and implementation of an entire system at one time.
• Tight control is maintained over the life of the project via extensive written documentation, formal reviews, and approval/signoff by the user and information technology management occurring at the end of most phases before beginning the next phase.

Software prototyping, is the development approach of activities during software development, the creation of prototypes, i.e., incomplete versions of the software program being developed.

The basic principles are:

• Not a standalone, complete development methodology, but rather an approach to handling selected parts 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 development 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.

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.

The basic principles are:

• A series of mini-Waterfalls are performed, where all phases of the Waterfall are completed for a small part of a system, before proceeding to the next increment, or
• Overall requirements are defined before proceeding to evolutionary, mini-Waterfall development of individual increments of a system, or
• The initial software concept, requirements analysis, and design of architecture and system core are defined via Waterfall, followed by iterative Prototyping, which culminates in installing the final prototype, a working system.

Rapid application development (RAD) is a software development methodology, which involves iterative development and the construction of prototypes. Rapid application development is a term originally used to describe a software development process introduced by James Martin in 1991.

The basic principles are:

• Key objective is for fast development and delivery of a high quality system at a relatively low investment cost.
• Attempts to reduce inherent project risk by breaking a project into smaller segments and providing more ease-of-change during the development process.
• Aims to produce high quality systems quickly, primarily via iterative Prototyping (at any stage of development), active user involvement, and computerized development tools. These tools may include Graphical User Interface (GUI) builders, Computer Aided Software Engineering (CASE) tools, Database Management Systems (DBMS), fourth-generation programming languages, code generators, and object-oriented techniques.
• Key emphasis is on fulfilling the business need, while technological or engineering excellence is of lesser importance.
• Project control involves prioritizing development and defining delivery deadlines or "timeboxes". If the project starts to slip, emphasis is on reducing requirements to fit the timebox, not in increasing the deadline.
• Generally includes joint application design (JAD), where users are intensely involved in system design, via consensus building in either structured workshops, or electronically facilitated interaction.
• Active user involvement is imperative.
• Iteratively produces production software, as opposed to a throwaway prototype.
• Produces documentation necessary to facilitate future development and maintenance.
• Standard systems analysis and design methods can be fitted into this framework.

Other methodology practices include:

• Object-oriented development methodologies, such as Grady Booch's object-oriented design (OOD), also known as object-oriented analysis and design (OOAD). The Booch model includes six diagrams: class, object, state transition, interaction, module, and process.
• Top-down programming: evolved in the 1970s by IBM researcher Harlan Mills (and Niklaus Wirth) in developed structured programming.
• Unified Process (UP) is an iterative software development methodology framework, based on Unified Modeling Language (UML). UP organizes the development of software into four phases, each consisting of one or more executable iterations of the software at that stage of development: inception, elaboration, construction, and guidelines. Many tools and products exist to facilitate UP implementation. One of the more popular versions of UP is the Rational Unified Process (RUP).
• Agile software development refers to a group of software development methodologies based on iterative development, where requirements and solutions evolve via collaboration between self-organizing cross-functional teams. The term was coined in the year 2001 when the Agile Manifesto was formulated.
• Integrated software development refers to a deliverable based software development framework using the three primary IT (project management, software development, software testing) life cycles that can be leveraged using multiple (iterative, waterfall, spiral, agile) software development approaches, where requirements and solutions evolve via collaboration between self-organizing cross-functional teams.

Software Development Process Evolves Various Processings. Hence, software development is not an easy task, it evolves various processings. According to IBM Research: "Software development refers to a set of computer science activities dedicated to the process".

Creating Designing Deploying Supporting Software.