Waterfall model of software lifetime model

Waterfall model

Until the 1980s, the waterfall model had been the only widely used life cycle model.

The traditional waterfall model

Characteristics

There are sequential and dependent stages between phases.

It contains two meanings:

① must wait for the previous phase of work to be completed before the latter stage of work can begin;

② the previous phase of the output document is the input document for the latter stage.

Deferred implementation of the point of view:

① Waterfall model before coding set up the system analysis and system design of the various stages, analysis and design phase of the basic task provisions, in these two phases mainly consider the target system logic model, does not involve the physical implementation of software.

② clearly distinguishes between logical design and physical design, delaying the physical implementation of the program as much as possible, is an important guideline for developing software according to waterfall model.

The point of view of quality assurance

① must complete the required documentation at each stage, without handing over the qualified documentation or completing the task at that stage.

② the completed documents are reviewed before each phase ends to identify problems early and correct the errors.

Advantages

You can force developers to adopt a standardized approach.

Documents that must be submitted at each stage are strictly defined.

All products required to be surrendered at each stage must be verified.

Disadvantages

Since the waterfall model relies almost entirely on written specifications, it is likely that the resulting software product will not really meet the needs of the user.

This can happen if there is a discrepancy between the requirements specification and the user's requirements.

Waterfall models are only available where the requirements have been determined at the beginning of the project.

Waterfall model of software lifetime model