SDLC

SDLC

(S)oftware (d)evelopment (l)ife (c)ycle

a systematic and disciplined approach to develope a software with low cost , superior quality and with no schedule slippage

PHASES IN

SDLC

1. feasibility analysis2.requirement analysis & specification3. design4. coding5. testing6.maintanence

FEASIBILITY ANALYSIS

1.analysis of project requirements : 1. input data and desired output 2. processing required to transform input to output 3.cost benifit analysis 4.schedule of project 2.technical feasibility : focuses on: 1. availability of software tools 2.availability of hardware 3.availability of skilled software professionals

at the end of this phase a feasibility report is generated.

REQUIREMENT

ANALYSIS

AND

SPECIFICATION

1.an SRS ( software requirement specification) document is generated.

2. SRS is a formal document includes performance, functional, software ,hardware and network requirements of the project.

3.it acts as an agreement between development team and customer .

DESIGN :

SRS requirement translated into a raw and logical structure .

CODING

implementing the design specified in design document to an executable programming language code.

TESTING

code is mapped against design document

test plan involves:1. test case generation2. testing criteria3. resourse allocation for testing

MAINTENANCE

1. handling errors that may exist in software even after testing phase

2. implementation of new requirements after software is deployed at customer location.

SOFTWARE DEVELOPMENT

APPROACHES

WATERFALL APPROACH

uses linear approach , that means it provide no process to go back to previous phase to handle changes in the requirement.

PROTOTYPING APPROACH

2. a prototype is generated acc to requirements of software that tells customer how the software is going to function and to get better knowledge of requirements.

until the customer approves the prototype , generating a new prototype is continued ( before finalizing and frozing the requirements )

types of prototypes :1. throwaway prototypes: those

prototypes that are eventually discarded rather than becoming a part of finally delivered software.

2. evolutionary prototypes: are those that evolve into the final system through iterative incoorperation of user(ustomer) feedback.

SPIRAL APPROACH

includes both iterative nature of prototyping approach and linear nature of waterfall approach.

example: evolution of windows operating system from windows 3.1 to windows 2000

WIN WIN SPIRAL APPROACH

here the concept is same as spiral approach but also includes time of identifying requirements,communication and planning

INCREMENTAL APPROACH

there are number of functional units , each containing group of similar tasks.

each functional unit is implemented with an increment and final product is acheived after all units are implemented in the development process.

limitation:

applicable only to large applications.

Various object oriented

concepts

1. classes and objects

classes: an abstract data type that contains set of attributes and functions.object: instance of class

all the objects share same copy of member functions ,but maintain a seperate copy of the member data.

2. inheritance :

sharing of attributes and behaviours among classes based upon hierarchial relationship.

3. abstraction:

focuses on essential inherent aspects of an entity ignoring its implementation detdails .

4. encapsulation:

also called information hiding .it involves preventing access to non-essential details .

5. polymorphism

concept of using same operatiors or functions in different ways depending on what they are operating on.

ROLE OF OOAD IN SDLC

ooad is a tool used in sdlc to reduce complexity of software