Features of WATERFALL MODEL

The Waterfall Model

—  is the root of all other models

—  still prevalent in general

—  exists in many versions

—  supported by many methods/techniques

Waterfall Model for Development

—  Here, steps (phases) are arranged in linear order

—  A step take inputs from previous step, gives output to next step (if any)

—  Exit criteria of a step must match with entry criteria of the succeeding step

—  It follows ‘specify, design, build’ sequence that is intuitively obvious and appears natural

  

5 Phases

1.   Analysis

2.   Design

3.   Implementation

4.   Testing

5.   Deployment / Operation

Analysis Phase:

—  Decide what the project is suppose to do, what the goal of the final product is

—  Do NOT think about how the program will accomplish tasks

—  Output of this phase - requirements document

—  Describes what program will do once completed

—  Example –

—  User manual: tells how user will operate program

—  Performance criteria (will complete X tasks in Y time)

Design:

—  Plan for implementation

—  Decide what structures will best suit your task

—  In object oriented programming, this is choosing the classes and methods to use (and create)

—  Output: Classes and methods description

—  Usually diagramed using UML, can use CRC cards

Implementation:

—  Actual coding part of the process

—  Edit à Compile à Run

—  Output: Completed program

Testing:

—  Run tests to verify the program works correctly

—  Remember the two main types of testing

—  Unit Testing

—  System Testing

—  Output: a report of the tests and their results

 Deployment:

—  AKA Operation, Maintenance

—  Users install program

—  Users use program for its intended purpose

—  Bug fixes

—  New features

Advantages of a Waterfall Model:

—  A waterfall model helps find problems earlier on which can cost a business less than if it was found later on.

—  Requirements will be set and these wouldn't be changed.

—   As everything is documented a new team member can easily understand what's to be done.

—  Implementers have to follow the design accurately

—  Highly disciplined process of documentation.

—  Easily observable development progress.

—  Easy to create budget

Disadvantages of a Waterfall Model:

—  If requirements may change the Waterfall model may not work.

—  Many believe it is impossible to make one stage of the projects life cycle perfect.

—  Difficult to estimate time and cost for each stage of the development process.

—  Constant testing of the design is needed.

—  Document centric; can be difficult for customer to understand.

—  Not user centered.

—  Makes assumptions about requirements that are inflexible.