Short note on the Water Fall model for Software Development.
The waterfall model is a sequential design process, often used in software development processes, in which progress is seen as flowing steadily downwards (like a waterfall) through the phases of Conception, Initiation, Analysis, Design, Construction, Testing, Production/Implementation, and Maintenance.
There are variants in this model as well but the model may be considered as having six distinct phases, described below:
1. Requirements analysis:
This first step is also the most important, because it involves gathering information about what the customer needs and defining, in the clearest possible terms, the problem that the product is expected to solve.
Analysis includes understanding the customer's business context and constraints, the functions the product must perform, the performance levels it must adhere to, and the external systems it must be compatible with. Techniques used to obtain this understanding include customer interviews, use cases, and "shopping lists" of software features.
The results of the analysis are typically captured in a formal requirements specification, which serves as input to the next step.
2. Design:
This step consists of "defining the hardware and software architecture, components, modules, interfaces, and data...to satisfy specified requirements" (Wikipedia). It involves defining the hardware and software architecture, specifying performance and security parameters, designing data storage containers and constraints, choosing the IDE and programming language, and indicating strategies to deal with issues such as exception handling, resource management and interface connectivity.
This is also the stage at which user interface design is addressed, including issues relating to navigation and accessibility. The output of this stage is one or more design specifications, which are used in the next stage of implementation.
3. Coding:
The design must be translated into a machine-readable form. The code generation step performs this task. If design is performed in a detailed manner, code generation can be accomplished mechanistically.
4. Testing:
In this stage, both individual components and the integrated whole are methodically verified to ensure that they are error-free and fully meet the requirements outlined in the first step.
An independent quality assurance team defines "test cases" to evaluate whether the product fully or partially satisfies the requirements outlined in the first step.
Three types of testing typically take place: unit testing of individual code modules; system testing of the integrated product; and acceptance testing, formally conducted by or on behalf of the customer.
5. Support:
This step occurs after installation, and involves making modifications to the system or an individual component to alter attributes or improve performance.
These modifications arise either due to change requests initiated by the customer, or defects uncovered during live use of the system. Typically, every change made to the product during the maintenance cycle is recorded and a new product release (called a "maintenance release" and exhibiting an updated revision number) is performed to enable the customer to gain the benefit of the update.
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