Life Cycle Model

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SOFTWARE PROCESS AND PROCESS ITERATION

Life cycle model
 To Describes the steps followed by the project

team to produce a tangible software product that fully meets the requirements of the component or the part that the project set forth to build.

Software Process
 A set of activities, together with ordering

constraints among them, such that if the activities are performed properly and in accordance with the ordering constraints.  The process that deals with the technical and management issues of software development is called SWP.  Successful project talks about Cost, schedule and quality.

Contd..
 A set of activities that leads to the production of a 

   

software product. There are many software processes, some fundamental activities are common to all software processes: Software Specification Software design and Implementation Software Validation Software evolution.

Software process
 Product Engineering process(produce desired

product) Development process Project Management process Software Configuration Management  Process Management process

ETVX Approach for process specification
 Entry Criteria
 Task  Verification

 Exit Criteria

A step in Development process
Predictability.

Input

Process

V&V

Output

SDLC
 A software development process, also known as

a software development life cycle (SDLC), is a structure imposed on the development of a software product.

Waterfall Model
 Linear Sequential Model  Water – tight phases  One phase is Completed before the next phase

starts

Life cycle model

Waterfall model problems
 Inflexible partitioning of the project into distinct stages

makes it difficult to respond to changing customer requirements.  Therefore, this model is only appropriate when the requirements are well-understood and changes will be fairly limited during the design process.  Few business systems have stable requirements.  The waterfall model is mostly used for large systems engineering projects where a system is developed at several sites.

Limitations of Waterfall model
 It assumes that the requirements of a system can 

 



be frozen before the design begins. Freezing the requirements usually requires choosing the hardware(because it forms a part of the requirements specification). A large project might take a few years to complete. “Big bang approach” – an entire software is delivered in one shot at the end. It encourages “requirements bloating”. It is a document-driven process that requires formal documents at each phase.

Prototyping Model
• Attractive idea for complicated and large systems for

which there is no manual process or existing system to help determine the requirements.. • Based on Currently known requirements. • Customer can get actual feel of the system. Types: 1. Throwaway Prototype 2. Evolutionary Prototype

Contd..
 Horizontal Prototype  A common term for a user interface prototype is

the horizontal prototype  It provides a broad view of an entire system or subsystem, focusing on user interaction more than low-level system functionality, such as database access  Vertical Prototype  A vertical prototype is a more complete elaboration of a single subsystem or function.

Contd..
 Types of prototyping

Major types: first two..  Throwaway prototyping  Evolutionary prototyping  Incremental prototyping  Extreme prototyping

Adv and Dis-Adv
 Advantages

Reduced time and costs: Improved and increased user involvement  Disadvantages of prototyping Insufficient analysis User confusion of prototype and finished system Developer misunderstanding of user objectives Expense of implementing prototyping: Excessive development time of the prototype

RAD Model
 Combines the features of waterfall model and 

 




prototyping model. Rapid application development (RAD) is a software dev.methodology that uses minimal planning in...
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