The waterfall model segments the software development process into sequential phases: planning, requirements definition, design, implementation, system testing, and maintenance. Each phase has defined inputs, processes, and outputs. The planning phase involves understanding the problem, feasibility studies, and developing a solution. Requirements definition produces a specification describing the required software functions and constraints. Design identifies software components and their relationships. Implementation translates the design into code. System testing integrates and accepts the software. Maintenance modifies the software after release. While the phases are linear, the development process is not always perfectly sequential.

1. Prepared by R.Nancy Beaulah

2.  Segments the software life cycles in to series
of successive activities.
 Each phase requires
 Well defined input information
 Well defined processes
 Well defined products
 Resources are needed for each phase
 Each phase utilizes explicit methods, tools
and techniques

3. Analysis
Design
Implementation
SystemTesting
Maintenance
Sometimes it
is called as
Water Fall
Chart

4.  Consist of two phases
▪ Planning
▪ Requirements Definition
 Activities of Planning
▪ Understanding the Problem
▪ Perform a feasibility study
▪ Developing a solution
▪ Determine acceptance criteria
▪ Planning the development process

5.  Products
▪ System definition
▪ Project plan
 System definition
▪ Expressed in English or in any natural language
▪ May use charts, figures, graphs, tables and equations
▪ Notations used depend upon the problem
 Project plan
▪ Life cycle model to be used
▪ Organizational structure

6. ▪ Preliminary development schedule
▪ Preliminary cost schedule
▪ Preliminary resource schedule
▪ Preliminary staffing schedule
▪ Tools and techniques used
 Time and cost are basically calculated
because it is not possible to estimate exactly
without doing basic design.

7.  PreliminaryCost Estimate – Planning Stage
 Refined Cost Estimate – Preliminary Design
Review
 FinalCost Estimate – Critical Design Review
 Requirements Definition
 It includes basic functions of software
components in hardware, software, and people
subsystem.

8.  The product of requirements definition
 The product of requirements definition is a
specification that describes
▪ The processing environment
▪ The required software functions.
▪ Performance constraints on the software.
▪ Exception handling
▪ Acceptance criteria

9.  Design phase:
 In the phased model, software design follows analysis
 Design phase identified software components
1. Functions.
2. Data streams
3. Data stores
 It specifies relationship among components.
 It specifies software structures.
 Maintains a record of design decision.
 Blueprint for the implementation phase.

10.  Design phase consist of
1. Architectural design
2. Detailed design
 Architectural design:
 It involves identifying the software components
dividing them into software modules and
conceptual data structures, specifying
interconnection among components.

11.  Detailed design
 It is concerned with the details of “how to”
▪ Package the processing modules.
▪ Implement the processing, algorithm, data structures
and interconnection among modules.

12.  Implementation phase:
 It involves translation of design specification into
source code and debugging, documentation and
unit testing of source code.
 Errors:
 Implementation phase may include errors in
routines, functions, logical errors,and algorithm,
errors in data structure layout.

13.  System testing:
 It involves 2 kinds of activities
▪ 1. Integration testing
▪ 2. Acceptance testing
 Integration testing:
 Developing a strategy for integrating the software
components into a function requires careful
planning so that modules are available for
integration when needed.

14.  Acceptance testing:
 It involves planning an execution of various type
of test that software system satisfied
requirements documents.
 After getting the acceptance from the customer
software system of released for production work
and maintenance phase.

15.  Maintenance Phase:
 It Includes
▪ the enhancement of capabilities.
▪ Adaptation of software to new processing environment.
▪ correction of software bugs.

16.  Phases are Linear
 Development Process is not Linear
 Development activities never proceed as in
water fall chart
 Only possible when it is possible to specify
everything at the beginning itself
 Suitable for developers who developed
similar systems

17.  Software EngineeringConcepts, Richard
Fairley