Prepared By: Prof. V. K - WordPress.comSoftware Myths (Practitioner Level) 18 Myths Reality Once we...

Prepared By: Prof. V. K. Wani






� Unit- 1

� Introduction to Software Engineering

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What is Software?


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Software Domains

Sr. No.

Domains Description Examples

1 System Collection of Programs written to service other programs

Compilers ,Editors,Drivers etc

2 Application Stand-alone programs that solve a specific business need.

VLC, MySQL

3 Embedded Embedded in Hardware to make it SMARTER

Keypad ControlCalculator

4 Scientific/Engineering

Characterized by “Number Crunching Algorithms ”

CAD,CFD

5 Webapps Network Centric S/w spans a wide array of applications.

Amazon, Flipkart

6 Artificial Intelligence Perform tasks requiring Human Intelligence, such as Visual Perception, Speech Recognition, Decision-Making and

GTA ,FIFA ,Biometric : PatternRecognition


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What is Software Engineering?

Is a Systematic and Disciplined approach towardsdevelopment of softwareBased on nature of problems Various tools and Technologiesare applied to develop Quality Software.


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Software Characteristics

Software is Engineered, Not Manufactured

Software Does not Wear Out

They are Custom Built rather than being assembled


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SOFWARE DOESN’T Wear Out ,But It Does Deteriorate..


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0

10

20

30

40

50

60

70

80Re

quir

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ts

Des

ign

Impl

emen

tati

on

Test

ing

Mai

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ance

Cost

Cost to fix an error increases as it is found later and later in the software lifecycle.

Relative costs to fix errorsRelative costs to fix errors


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Legacy Software

Software that are developed decades ago and have been continuallymodified to meet changes in business requirements and computingplatforms

costly to maintainExhibit poor qualityExample : Microsoft Office [Current Version : 2017]

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Software Engineering Layard Technology…

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Provides Automated / Semi- Automated Support for process & Methods

provide the technical way for buildingsoftware1. Communication 2. Requirement Analysis3. Analysis & Design 4. Implementation 5. Testing

Glue that holds the technology layers together and enables rational and timely development of computer software

The Degree of Goodness1. Correctness 2. Maintainability 3. Integrity 4. Usability


Software Myths (Management Level)16

Myths RealityAddition of more software specialiststhose with higher skills and longerexperience may bring the schedule backon the track!

Unfortunately, that may further delay the schedule

Management may be confident about the state of the art and development tools company have

But the Latest Hardware configuration will not help in producing high Quality software

There is a Book that contain Standards and procedures for developing Software

Does it contain Modern engineering Practices?Does it Focus on Quality?Is it foolproof?


Software Myths (Customer Level)

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Myths RealityA general statement is sufficient to getstarted with the development ofsoftware. No need to mentionrequirements

If we do so, we are headingtowards a disaster

Project Requirement continuouslychanges but can be easily accommodatedin software

If the Changes are requested in earlier stages of software then can be easily carried out but if requested in later stages Cost of change is rapidly increases

Software is easy to change. The reality is totally different


Software Myths (Practitioner Level)

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Myths RealityOnce we write the program and get itwork, our job is done

Usually, the problems just begin

Until I get the Program running , I haveno way of assessing quality

However, quality assessment techniquesshould be used through out the softwaredevelopment life cycle

When the project is SuccessfullyDelivered, Product is only runningprogram.

It is just a small part of software but italso include Documentation, Help Filesand Guidelines for handling software.


Software Process19

A process is a collection of activities, actions and tasks that are performedwhen some work product is to be created.

it is an adaptable approach that enables the people doing the work to pickand choose the appropriate set of work actions and tasks.

Purpose of process is to deliver software in a timely manner and withsufficient quality to satisfy those who have sponsored its creation and thosewho will use it.


Software Process Cont….20


Umbrella Activities

Umbrella Activity Occur through out the process .

It Focus on progress, quality, change, and risk. The Various Activities are

1. Software project tracking and control: assess progress against the plan and takeactions to maintain the schedule.

2. Risk management: assesses risks that may affect the outcome and quality.

3. Software quality assurance: defines and conduct activities to ensure quality.

4. Formal Technical reviews: assesses work products to uncover and remove errorsbefore going to the next activity.

5. Measurement: define and collects process, project, and product measures to ensurestakeholder’s needs are met.


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Umbrella Activities

6. Software Configuration Management: It Manages the effect of changes throughoutthe process.

7. Reusability Measurement: It Define the criteria for product Reuse.

8. Work product preparation and Production: It Includes Activities require to createdocuments.


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Generic Process Model

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Generic Process Activities are:1. Communication2. Planning3. Modeling4. Construction5. Deployment


Process Flow24

Communication Planning modeling Construction Deployment

Communication Planning modeling Construction Deployment

(b) Iterative process flow

(a) Linear Process Flow


Process Models25

Process Model

Perspective Process Model

Specialized Process Model

Waterfall Model

Incremental Model

Evolutionary Model

V Model

Incremental

RAD Model

Prototyping Model

Spiral Model

Concurrent ModelPrepared By: Prof. V. K. Wani

Waterfall Process Models26


Waterfall Process Models Cont…

Advantages:1. Very Simple & Easy to Understand2. Is a Systematic & Sequential approach for S/W Development3.In this process each phase is processed and completed at one time so overlapping is

avoided.4. Easy to manage as all requirement are very well understood in the beginning.

Disadvantages :1. Problems in this model remains uncovered until testing.2. The Biggest Drawback is Blocking State3. According to model customer have to state requirement at beginning only which is

difficult for customer.4. Customer get working version too late so not a realistic approach5. Suitable only for small projects.

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V- Model28


V Model Cont….

Advantages1. Progress goes in very systematic way.2. Best suitable for small and medium size projects.3. Testing starts from requirement phase.4. Easy to keep track on progress.

Disadvantages1. Not suitable for bigger and complex projects2. Not a good option If Requirement changes frequently.3. The client sees the only final project, not intermediate

modules.4. No scope for risk management

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Incremental Process Model

This Model Helps to implement limited set of customer requirementquickly and Delivered to customer

The Modified and Remaining requirements are implemented step bystep

The Overall Functionalities are split to smaller modules and then themodules are quickly developed and delivered.

Types of Incremental Process Model

1. The Increment Model2. The RAD Model

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The Increment Model31


The Increment Model Cont…

Combines elements of waterfall model in iterative manner.

assist stakeholders to better understand what is to be built

Series of released called increments that progressively provides

more functionality.

Eg. Word processing system.

First increment is core product that is opened for customer to use.

Early increments are stripes down version of final product

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The Increment Model Cont…

Advantages1. The Model can be used with small Development Team 2. The initial Delivery of Product is Faster 3. The Customer Can Respond to Functionality after each increment

Disadvantages1. The Cost of Final product may be increased2. After each increment customer may demand new requirement which may cause

problem to existing System3. It Require Clear & Complete planning before the system Is broken in to increments


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The RAD Model34

Rapid Action Development is High Speed Adoption of Waterfall Model.

Initial activity start with communication between customer and developer.

Depending upon requirements the team are assigned work.

At last work product of every Team is integrated to form a product as whole.


The RAD Model Cont…35

Com m unicat ion

Planning

Mode lingbusiness modeling dat a modeling process modeling

Const ruct ioncomponent reuse aut omat ic code generat ion t est ing

De ploym e nt

6 0 - 9 0 days

Team # 1

Mo d el ingb usi ne ss m o de l in g d a t a m od e l ing p rocess m od e l i ng

Co nst ruct io nco m pon en t reu se a u t o m a t i c co de ge ne ra t io n t e st ing

M o d e lin gbus ines s m odeling data m odeling proc ess m odeling

C o n st ru ct io ncom ponent reus e autom at ic code generat ion tes t ing

Team # 2

Team # n

in t egrat ion deliv ery feedback


Advantages1. Product can be developed within short time period2. Increase Reusability,3. Minimal Code Writing4. Resolve Integration Issues.

Disadvantages1. Sufficient manpower to create team2. All team should work in parallel3. Not appropriate when technical risk is high4. Only for large products5. Reduce Scalability6. Reduced Features

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The RAD Model Cont…


They are basically iterative Once the requirements are analyzed, they pass through aseries of iterations till the complete software is developed.The evolutionary models mainly support the programmer to develop the completeversion of a software., after each release, based on the review given by the reviewers

Types of Evolutionary Models1. The Prototyping Model2. The Spiral Model3. Concurrent Development Model

Evolutionary Models


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The basic idea in Prototype model is that instead of freezing therequirements before a design or coding can proceed,A prototype is built to understand the Clear requirements.This prototype is developed based on the currently knownrequirements.Compelling need to provide a limited set of software functionallyto users quickly and then refine and expand.

The Prototyping Model


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Advantages:It makes requirement more Clear and System more Transparent

Disadvantages:The Quality may get compromised because of prototyping quickly



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The Spiral Model41


Spiral Model Cont…42

Have the iterative nature of prototyping with the controlled and

systematic aspects of waterfall model

Provides the potential for rapid development of increasingly

more complete versions of the software

This model is divided in to set of framework activities, Each

activity represent one segment of spiral.

Can be adopted to apply throughout the entire life cycle of an

application from concept development to maintenance


Spiral Model Cont…43

Advantages

1. Project monitoring is very effective and easy

2. It reduces the risk in software development

3. Risk management is in-built feature of the model

Disadvantages

1. Cost of approach is high

2. Not suitable for low risk approach

3. Rules and protocol must be followed strictly in the approach.


Concurrent Model44


Concurrent Model45

It is applicable to all types of software development

Provides an accurate picture of the current state of a project

It cab represent diagrammatically a series of tasks, framework activities,

and their associated states

Events generated at one point the process network trigger transitions

among the states

The Above diagram represent the one element of concurrent process

model.


Concurrent Model

Advantages

1. applicable to all types of software development It reduces the risk in softwaredevelopment

2. Provides an accurate picture of the current state of a project

3. Easy to Use and Understand


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Specialized Process Model47

Types of Specialized Process model1. Component-based development2. Formal methods model3. Aspect-oriented software development


Component-based development

Incorporates many of the characteristics of spiral model

It is evolutionary in nature, demanding an iterative approach

This model compasses application from prepackaged software components

i.e. from existing software modules.


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Formal Methods Model

Includes a set of activities that leads to formal mathematical specification

of computer software

Enable you to specify, develop and verify a computer-based system by

applying precise, mathematical notation

Provide a mechanism for eliminating many of the problems that are

difficult to overcome using other software engineering paradigms

Ambiguity, incompleteness and inconsistency can be discovered and

corrected more easily


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Aspect Oriented S/W Development Model

To address particular problems and make program easier and to maintain good

reusability, Aspect Oriented S/W development model is used.


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CleanRoom Software Engineering

Is a approach to Build correctness in software being developedRemoving dependencies on costly processes.Main concept is to write Correct code right from first lineIt takes Software development to next level.In traditional approach Software failure lead to hazards.Cleanroom software engineering can guarantee, it will not leadto hazards.


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CleanRoom Design

Cost effective and Time effective

Systematic and disciplines approach

Remove possible errors in early stage

Mills, Dyer and Linger have proposed, but gained no popularity

Another research has explains three possible reason for failure1. Theoretical and Mathematical2. Offers no testing3. Rigorous process in its development stages


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CleanRoom Strategy

Specialized version of incremental model

Increments are developed and verified by small team

Final product is integrated from all increments.

Sequence is as follow.


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CleanRoom Strategy


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CleanRoom Process Model

Cleanroom uses Box structure specification, A Box System or

some part or some aspect of system.

Black Box: Specifies the Behavior such as specification &

functionality of a system .

State Box: Specifies the State data & operations as well input

& output are represented.

Clear Box: Specifies the all procedural design of Previous

boxes i.e. State Box.


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Software Quality Assurance

Planned and Systematic Approach to the Evaluation of the Quality of

1. Software Product Standards

2. Processes

3. procedures

Assures that Standards and Procedures are Established and

Followed throughout the Software Development Process


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Standards and Procedures

Framework for which Software EvolvesStandards: Established Criteria to which Software Products areComparedProcedures: Established Criteria to which Development and ControlProcedures are FollowedSQA is based on the Following of Standards and Procedures ProperDocumentation of Standards and Procedures is Necessary for SQASQA Activities

— Continuous Monitoring,— Product Evaluation, and— Auditing rely

Any number of different Standards and Procedures can be used on agiven system


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Types of Standard

1. Documentation Standard2. Design Standard3. Code Standard


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Types of Standard

Documentation Standard:Specify Form and Content for Planning, Control, and Product. Documentation Provide Consistency throughout a SystemDocumentation can be written in any form Each Practice should be Documented so it can be Repeated or Changedlater if neededDesign StandardsSpecify the Content and Form of how Design Documents are DevelopedProvide Rules and Methods to Transfer:

1. Software Requirements to Software Design2. Software Design into Software Design Documentation

Many Major Companies have Design Development Software to aid in theProcess


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Types of Standard

Code StandardsSpecify what Language the Code is written in and Define any Restrictions on Language FeaturesCode Standards Define:

•Legal Language Structures•Style Conventions•Rules for Data Structures and Interfaces•Internal Code Documentation

Using Methods such as “Peer Reviews”, “Buddy Checks”, and Code Analysis can Enforce Standards


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SQA Activities

SQA is composed of a variety of tasks associated with two different

constituencies- the software engineer who do technical work and an

SQA group that has responsibility for quality assurance planning,

oversight , record keeping analysis and reporting.

The charter of the SQA group is to assist software team in achieving

a high quality end product.

The SE recommends a set of SQA activities that address quality

assurance.


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Activities…

Prepare an SQA plan for a project Participates in the development of the project’s software process

description Reviews software engineering activities to verify compliances

with defined software process Audits designated software work products to verify compliance

with those defined as part of the software process

Ensures that deviations in software work and work products are

documented and handled according to a documented procedures

Records any noncompliance and reports to senior management


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Software Quality Framework

Mccall’s Quality FactorISO 9126 Quality Factor


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Mccall’s Quality Factor


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ISO 9126 Quality Factor


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Thank You


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