chapter 01 product

7/31/2019 Chapter 01 Product

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Software Engineering

BY

Vaibhav P. Vasani

Manohar Phalke Polytechnic Sion-22

By Prof. Vaibhav P. Vasani


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What is Software Engineering?

Group Exercise

Break into groups of 4 or 5 (i.e. your

neighbours, dont move around the theatre) Take 5 minutes to write down a definition of

software engineering - this can be in pointform

After 5 minutes, we will collect definitionsfrom the class


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Some statistics One in four systems miscarry 20% turnover in staff is not uncommon Major corporations have a backlog of up to a 30

months Large systems take 3 to 5 years to develop Corporations are spending up to 20% of revenue on

Information Technology

Y2K problem took up to 50% of resources in at leastone bank in Australia. Many of the systems werebuilt in the 1980s


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Need Y2K bug

Computer software drives business decisionmaking basis for modern scientific investigation and

engineering problem solving. transportation, medical, telecommunications,

military, industrial processes, entertainment,office products..

Software is virtually inescapable in a modernworld



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Need UPs and DOWNs of DotCom people bet their jobs, their comfort, their

safety, their entertainment, their decisions,and their very lives on computer software. It

better be right. DEFINITION The technology encompasses a process, a set

of methods, and an array of tools that we callsoftware engineering.



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A good software product?


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The Product



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THE EVOLVING ROLE OF SOFTWARE

software takes on a dual role Product(computing potential) Vehicle for delivering a product(networks, information)

resides within a cellular phone or operates inside amainframe computer, software is an informationtransformer producing, managing, acquiring,modifying, displaying, or transmitting information

that can be as simple complex as a multimedia presentation



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The lone programmer replaced by a team of software specialists(focus on one part of the

technology). Q. asked for modern SW development Why does it take so long to get software finished? Why are development costs so high? Why can't we find all the errors before we give the

software to customers? Why do we continue to have difficulty in

measuring progress as software is beingdeveloped?



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What is Software?

instructions (programs) that when executed providedesired function and performance

data structures that enable the programs toadequately manipulate information

documents that describe the operation and use of the programs



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Hardware ? hardware is built(analysis, design,

Construction, testing)



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Software Characteristics Software is developed or engineered, it is not

manufactured in the classical sense Depends upon people applied & work Approach are different No spare part in case of SW

software doesnt wear out software is custom built(industry is moving

toward component-based assembly)(ex. GUI) software is complex



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Quality problems are nonexistent for S/W H/W affected by dust, vibration, temperature ,

abuse ,environment maladies

No Environment Maladies Undesired Defects Changes in SW



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Failure (Bathtub) Curve for Hardware



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Idealized and Actual Failure Curves for Software


B d t i f SW


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Broad categories of SW System SW

Services to other programs E.g. compilers, editors , file management OS components, drivers, n/w SW, Scheduling, resources sharing , process management complex

DS, External interface Application SW

Specific Bussiness Need Stand Alone

Real-time software. Software that monitors/analyzes/controls real-world events as

they occur is called real time. data gathering formats information from an externalenvironment, response (typically ranging from 1 millisecond to 1second) can be maintained.


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Business software. Discrete "systems" (e.g., payroll, accounts receivable/payable,

inventory) have evolved into management information system(MIS) software that accesses one or more large databasescontaining business information.

It restructure existing data in a way that facilitates businessoperations or management decision making.

Engineering and scientic software. Astronomy, volcano logy, Space Shuttle Automotive stress analysis , CAD ,Simulators

Embedded software. Personal computer software or Product-line SW Web-based software. AI-SW (Robotics, Pattern recognization, games)


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Software Myths Management

We have book of stds and procedures for building SW. Reality:-not aware of existence of book, does not reflect newpractices, not complete We have new computers Reality:- CASE tools are more impt. than H/W, developers are

not able to use effectively

Mongolian horde concept(Well add more people to catchup) Reality:- time spent time to teach to newcomers results in

reducing productivity. I outsourced it, Im done Reality:- Not able to manage internally how he can manage

outsourced one


S ft M th


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Software Myths Customer

We have general objectives, lets start Reality :- formal and detailed description of the information

domain, function, behavior, performance, interfaces, designconstraints, and validation criteria is essential.

Change is easily accommodated Reality:- early requests -- accommodated easily

review requirements and recommend modifications withrelatively little impact on cost.Requested during software design -- cost growsResources & design established-- requires additionalresources and major design modification additional costChanges in function, performance, interface, or othercharacteristics during implementation (code and test) have asevere impact on cost.

after production--magnitude more expensiveBy Prof. Vaibhav P. Vasani


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The Cost of Change


S ft M th


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Software Myths Practitioner

Well write it and be done Reality :-the sooner you begin 'writing code', the longer it'll

take you to get done. I cant assess quality until it is running Reality :- applied from the inception of a project the

formal technical review, Software reviews I only need to deliver code Reality :- A program is One part of Software configuration Software engineering is about meaningless documents Reality:- its about creating Quality, leads to reduced the

rework, leads to faster delivery times



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Software Poses Challenges


How do we ensure the quality of the software thawe produce?

How do we meet growing demand and stillmaintain budget control?

How do we upgrade an aging "software plant?"

How do we avoid disastrous time delays?

How do we successfully institute new softwaretechnologies?

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