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Phased Life Cycle Model
Prepared by R.Nancy Beaulah
Phased Life Cycle Model
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
Phases
Analysis Design
Implementation
System Testing
Maintenance
Sometimes it is
called as Water
Fall Chart
Analysis
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
Analysis
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
Analysis
▪ 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.
Analysis
Preliminary Cost Estimate – Planning Stage
Refined Cost Estimate – Preliminary Design Review
Final Cost Estimate – Critical Design Review
Requirements Definition It includes basic functions of software
components in hardware, software, and people subsystem.
Analysis
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
Design
Design phase: In the phased model, software design follows
analysis Design phase identified software components
1. Functions.2. Data streams3. Data stores
It specifies relationship among components. It specifies software structures. Maintains a record of design decision. Blueprint for the implementation phase.
Design
Design phase consist of1. Architectural design2. Detailed design
Architectural design: It involves identifying the software
components dividing them into software modules and conceptual data structures, specifying interconnection among components.
Design
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.
Implementation
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.
System Testing
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.
System Testing
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.
Maintenance Phase
Maintenance Phase: It Includes▪ the enhancement of capabilities.▪ Adaptation of software to new processing
environment.▪ correction of software bugs.
Summary
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
Reference
Software Engineering Concepts, Richard Fairley