Main TA model

System Development Lifecycle Model

A system development lifecycle model is a generalized (abstract) description of the development process. It is a way of describing the process from a specific point of view. When describing process models, people usually refer to activities such as data model planning, user interface design, etc. However, they can also include documentation and role descriptions.

There are two fundamentally different approaches found in process models:

---

1. Intensive Planning (Tugev planeerimine)

This older approach involves detailed planning of activities and software, with strict adherence to the plan at each stage of development. Progress in the development process is measured according to the same predefined scheme.

---

2. Accelerated (Agile) Development (Agiilne arendus)

In this approach, planning is done in parts (gradually), allowing for changes to the process in response to evolving user requirements. The adoption of accelerated development came as a result of rapidly changing customer needs. The process must be flexible and capable of reacting to changes, expansion, and adapting to new product requirements.

---

In the past, development models were strictly categorized as either one or the other, but according to Ian Sommerville, such rigid separation is no longer appropriate. Many models can now be used in both an agile and a plan-driven way.

---

Over the years, several general system development models have been proposed, and the most important ones are:

• Waterfall Model (Koskmudel, also called the cascade model)
• Spiral Model (Spiraalmudel)
• Incremental Model (Inkrementaalmudel)
• Prototyping (Prototüüpimine)
• V-Model (V-mudel)
• Agile Model (Agiilne mudel)