Fundamentals of software development

Fundamentals of Software
Development
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Contents in this Project…
 What is SOFTWARE ?
 Characteristics of Software.
 Software Engineering
 Layer Approach
 Need of Software engineering
 Software Development Models / Life Cycle Models
 Classical Waterfall model
 Iterative Waterfall model
 Prototyping model
 Spiral model
 RAD model

Software
 What is software ?
 Software is “ Collection of computer programs
,procedures ,rules ,associated documents and
concerned data with the operation of data processing
system.
 Software is Divided into :
 1. System Software
 Ex : Operating System
 2.Application Software
 Microsoft Word ,VLC , AutoCAD

CharacteristicOf Software
 Understandability:-software should be easy to
understand.
 Cost:-software should be cost effective as per its usage.
 Maintainability:-software should be easily maintainable
and modifiable in future.
 Modularity:-software should have modular approach so
it can be handled easily for testing.
 Reliability:-it should have the capability to provide
failure free services.

 Portability:-software should have the capability to be adapted
for different environments.
 Documentation:-software should be properly documented so that
we can re-refer it in future.
 Reusability:-it should be reusable, or its code or logic should be
reusable in future.
 Interoperability:- software should be able to communicate with
various devices using standard bus structure and protocol.

SoftwareEngineering
 Software Engineering is the application of a systematic,
disciplined and quantifiable approach to the
development, operation and
maintenance of software.
 Software Engineering provide framework that guides the
software
engineers to develop the software.
 Software Engineering tells how software will work with
machines.

Softwareengineering - A Layered Approach
 As We can see there are
Main four Layers in this
Layered approach.
 1. A quality focus
 2. Process
 3. Methods
 4. Tools A Quality
Focus
Process
Method
Tools

1. A QualityFocus Layer
 Software engineering mainly focuses on quality product.
 It checks whether the output meets with its
requirement specifications
or not.
 Every organization should maintain its total quality
management.
 This layer supports software-engineering.

2. Process Layer
 It is the heart of software engineering.
 It is also working as foundation layer.
 Software process is a set of activities together if
ordered and performed
properly, the desired result would be produced.
 It defines framework activities.
 Main objective of this layer is to deliver software in
time.

3. Methods 4. Tools
 It describes 'how-to‘
build software product.
 It creates software
engineering environment
to software product
using
CASE tools.
 (CASE tools combines
software, hardware and
software engineering
database).
O It provides
supports to below
layers.
O Due to this layer ,
process is
executed in proper
manner.

Need of software engineering
 To help developers to obtains high quality product.
 To develop the product in appropriate manner using life
cycle models.
 To acquire skills to be a better programmer.
 To provide a software product in a timely manner.
 To provide a quality software product.
 To provide a software product at an agreed cost.
 To develop ability to solve complex programming
problems.

SoftwareLife cycle models
 Different software life cycle models are given below.
1. Classical waterfall model
2. Iterative waterfall model
3. Prototyping model
4. Spiral model
5. RAD model

1. Classical waterfall model
Feasibility study
Requirement analysis &
specification
Design
Coding & testing Unit
Integration & system
testing
Maintenances
Development Phase

 This model was originally proposed by royce(1970).
 It is also called ‘traditional waterfall model’ or
‘conventional waterfall model’
 This model breakdown the life cycle into set of phases like:
 *)feasibility study
 *)requirements analysis and specification
 *)design
 *)Coding and unit testing
 *)integration and system testing
 *)maintenance

1.feasibility study
 Aim of this phase is to determine whether the system
would be financially and
technically feasible to develop the product.
 This is an abstract definition of the system.
 It includes the analysis of the problem definition and
collectionn of relevant info
of input, processing and output data.
 · Collected data are analysed for :
 An abstract definition
 Formulation of different solutions.
 Analysis of alternative solutions.
 and acceptance within the organization.

2. Requirements analysis andspecification
 Aim of this phase is to understand the exact requirements
of the
customer and to document them properly.
 Also reduces communication gap between developers and
customers.
 Two different activities are performed during this phase
1. Requirements gathering and analysis
2. Requirements specification
 Requirement gathering: The goal of this activity is to
collect all
relevant information from the customer regarding the
product to be
developed.
· This is done to clearly understand the customer
requirements so that
incompleteness and inconsistencies are removed

3. Design
 The goal of the design phase is to transform the
requirements specified
in the SRS document into a structure that is suitable for
implementation
in some programming language.
 This phase affecting the quality of the product.
 Two main approaches are concerned with this phase.
 (1) Traditional Design Approach
 Structural Analysis
 Stuctural Design
 (2) Object Oriented Design Approach

4. Coding & Testing
 The goal of the design phase is to transform the
requirements specified
in the SRS document into a structure that is suitable for
implementation
in some programming language.
 This phase affecting the quality of the product.
 Two main approaches are concerned with this phase.
 (1) Traditional Design Approach
 Structural Analysis
 Stuctural Design
 (2) Object Oriented Design Approach

5. Integration and system testing
 Goal of this phase is :- to ensure that the developed system works
well
to its requirements described in the SRS document.
 Basic function of testing is to detect errors. Ss it is also called
quality
control measure.
 Testing procedure is carried out using test data: Program test and
System test. Program is done on test data and system test is done
actual
data.
 It consists of three different kinds of testing activities.
 α Testing
 ß Testing
 Acceptance testing

6. Maintenance
 It requires max efforts to develop s/w product.
 This phase is needed to keep system operational.
 Generally maintenance is needed due to change in the environment
or
the requirement of the system.
 Maintenance involves performing following three kinds of
activities .
 Corrective maintenance - Correcting errors that were not
discovered
during the product development phase.
 Perfective maintenance - Improving and enhancing the
functionalities
of the system according to the customer's requirements.
 Adaptive maintenance - Porting the software to work in a new
environment and ensure working.

2. Iterative waterfall model
Feasibility study
Requirement
analysis &
specification
Design
Coding & testing
Unit
Integration &
system testing
Maintenances

Iterative waterfallmodel
 Iterative waterfall model is by far the most widely used
model. Almost
every other model is derived from the waterfall model.
 The principle of detecting errors as close to its point of
introduction as
Possible-is known as phase containment of errors.
 Phase containment of errors can be achieved by
reviewing after every
milestone.

Incremental model
 It is also referred as the successive version of waterfall
model using
incremental approach and evolutionary model.
 In this model, the system is broken down into sseveral
modules which
can be incremented implemented and delivered.
 First develop the core product of the system. The core
product is used
by customers to evaluate the system.
 The initial product skeleton is refined into increasing levels
of
capability by adding new functionalities in successive
versions

RAD Model
Testing &
Turnover
Applicatio
n
modelAing
Process
Amodeling
Data
Amodeling
Business
modelAing

RAD Model
 Business modelling: The information flow is identified
between various business functions.
 Data modelling: Information gathered from business
modeling is used to define data objects that are needed
for the business.
 Process modelling: Data objects defined in data
modelling are converted to achieve the business
information flow to achieve some specific business
objective. Description are identified and created for
CRUD of data objects.
 Application generation: Automated tools are used to
convert process models into code and the actual system.
 Testing and turnover: Test new components and all the
interfaces

Prototyping Model
Quick
Design
Build
Prototype
Customer
Evaluation
of
prototype
Refine
Requirem
ents Design
Implement
Test
Maintenance
Requirement
gathering

Prototyping Model
 Prototype is a working physical system or sub system.
Prototype is nothing but
a toy implementation of a system.
 In this model, before starting actual development, a
working prototype of the
system should first be built.
 A prototype is actually a partial developed product.
 Compared to the actual software, a prototype usually
have
· limited functional capabilities
· low reliability
· inefficient performance

When to use RAD model:
 Prototype model should be used when the desired
system needs to have a lot of interaction with the end
users.
 Typically, online systems, web interfaces have a very
high amount of interaction with end users, are best
suited for Prototype model. It might take a while for a
system to be built that allows ease of use and needs
minimal training for the end user.
 Prototyping ensures that the end users constantly work
with the system and provide a feedback which is
incorporated in the prototype to result in a useable
system. They are excellent for designing good human
computer interface systems.

Spiral Model
 1. To determine the objectives, alternatives and
constraints. We try to understand the product objectives,
alternatives in design and constraints imposed because of
cost, technology, schedule, etc.
2. Risk analysis and evaluation of alternatives. Here we try
to find which other approaches can be implemented in order
to fulfill the identified constraints. Operational and
technical issues are addressed here. Risk mitigation is in
focus in this phase. And evaluation of all these factors
determines future action.
3. Execution of that phase of development. In this phase
we develop the planned product. Testing is also done. In
order to do development, waterfall or incremental approach
can be implemented.
4. Planning the next phase. Here we review the progress
and judge it considering all parameters. Issues which need
to be resolved are identified in this phase and necessary
steps are taken.

Fundamentals of software development

Fundamentals of software development

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