Diapositiva 1
Scope of Software Engineering
Muhammad Naveed ZafarEducational Background BS in Computer
Science(Bahria University)
MS in Software ProjectManagement(FAST University)* Professional
ExperienceProject Manager(NevTech)
Faculty Member (Aptech MSG)
Project CoordinatorAMI
Software EngineerGoSafe Systems
AgendaWhat, Why and Aspects of Software Engineering ?Horror
Software Failure StoriesSoftware Engineer Line of ActionsSoftware
Engineering StakeholdersEngineering ApproachRoles and Members of
Development TeamProblem Solving ParadigmsSDLC ModelsBest Practices
to be Adopt Scrum Methodologies
What is software?Computer programs and associated
documentationSoftware products may be developed for a particular
customer or may be developed for a general marketSoftware products
may beGeneric/COTS - developed to be sold to a range of different
customersCustom- developed for a customer according to their
specification
Short forcommercialoff-the-shelf, an adjective that describes
softwareorhardwareproducts that are ready-made and available for
sale to the general public4
What is Engineering?Engineering is The application of scientific
principles and methods to the construction of useful
structures.Examples:Mechanical engineeringComputer engineeringCivil
engineeringChemical engineeringElectrical engineeringNuclear
engineeringAeronautical engineering
What Actually Software Engineering?A discipline whose aim in the
production of software thatmeets the clients needsfault-free
delivered on timedelivered within budgeteasy to modify
Why the need for Software Engineering?Software Crisis:
Unacceptable low quality of software, exceeds deadline and
budget.
*Completed late, over budget, and/or with features missing
Why Software Engineering ?The problem is complexityMany sources,
but size is a key:Mozilla contains 3 Million lines of codeUNIX
contains 4 million lines of codeWindows 2000 contains 108 lines of
codeSecond is roles define Third is uncertainty of inputs and their
timingFourth is the continuing changing environment and demands.
Software engineering is about managing all the sources of
complexity to produce effective software.
Software Engineering AspectsHistorical Aspects:1967, a NATO
group coined the term Software Engineering1968 NATO Software
Engineering Conference concurred that Software production should be
an engineering-like activity.Using philosophies and paradigms of
established engineering disciplines to solve Software Crisis: that
the quality of software was generally unacceptably low and that
deadlines and cost limits were not being met.
9
Economic AspectsSoftware Engineering v.s. Computer ScienceThe
computer scientist investigates several ways to produce software,
some good and some bad.But the software engineer is interested in
only those techniques that make sound economic sense. For example:
A coding technique that can execute very efficiently but with
higher maintenance cost may not be a good choice, since maintenance
occupies a lot of resources of the whole life cycle.Software
Engineering Aspects
10
Maintenance AspectsSoftware Life Cycle / Software
ProcessRequirements PhaseSpecification (Analysis) PhasePlanning
PhaseDesign PhaseImplementation PhaseIntegration PhaseMaintenance
Phase (highest cost among all these phases)Retirement Software
Engineering Aspects
11
Maintenance AspectsMaintenance67%Approximate relative costs of
the phases of the software life cycle.Maintenance is so important
that a major aspect of software engineering consists of techniques,
tools, and practices that lead to a reduction in maintenance
cost.
12
Horror Software Failure StoriesPatients died as a consequence of
severe overdoses of radiation.US Treasury Department mailed
incorrectly printed Social Security Checks.Interest miscalculated
on student loans resulting in higher monthly payments.Mars Climate
Orbiter spacecraft crashes into the surface of Mars because of
measurement conversion error.Consequences of software failures
range from inconvenience to death!
Software Engineer Line of Actions
Software Engineers should adopt a systematic and organised
approach to all aspects of software development.use appropriate
tools and techniques depending on the problem to be solved, the
development constraints and the resources availableUnderstand and
communicate processes for improved software development within
their organizationBe effective team members and/or leaders.Can be
very technical or more managerial depending on organizational
need.
Where Does the Software Engineer Fit In?Computer Science:
focusing on computer hardware, compilers, operating systems, and
programming languages
Software Engineering: a discipline that uses computer and
software technologies as a problem-solving tools
15
Where Does the SW Engineer Fit in?...Relationship between
Computer Science and Software Engineering
16
Qualities of Good Software?Good software engineering must always
include a strategy for producing quality softwareThree ways of
considering qualityThe quality of the productThe quality of the
processThe quality of the product in the context of the business
environment
17
Who Does Software Engineering?Customer: the company,
organization, or person who pays for the software systemDeveloper:
the company, organization, or person who is building the software
systemUser: the person or people who will actually use the
system
18
Who Does Software Engineering? (continued)Participants
(stakeholders) in a software development project
19
Engineering ApproachBuilding a SystemRequirement analysis and
definitionSystem designProgram designWriting the programs Unit
testingIntegration testingSystem testingSystem
deliveryMaintenance
20
Members of the Development TeamRequirement Analysts: work with
the customers to identify and document the requirementsDesigners:
generate a system-level description of what the system us supposed
to doProgrammers: write lines of code to implement the
designTesters: catch faultsTrainers: show users how to use the
systemMaintenance Team: fix faults that show up laterLibrarians:
prepare and store documents such as software
requirementsConfiguration Management Team: maintain correspondence
among various artefacts.
21
Members of the Development Team (continued)Typical roles played
by the members of a development team
22
Secrets of Successful Projects
Problem Solving ParadigmsSeveral techniques have been suggested
to help solve the software crisis.~1975-1985: Structured
ParadigmStructured Systems Analysis, Composite/Structured Design,
Structured Programming, Structured Testing Lead to major
improvements for software industry. But only good for small
programs (say, 5,000-50,000 lines of codes)Not so good in software
maintenance aspects, (for instance, because of the separation of
action-oriented and data-oriented in structured
paradigm).Object-Oriented ParadigmAn object is a unified software
component that incorporates both data and actions that operate of
those data. --> More Promising!
24
Why use Object Oriented Paradigm?Classical Structured
ParadigmFocus on functions of systemObject-Oriented ParadigmFocus
on objectsImplementation details are local to the objectRegression
fault (fault produced by seeming unrelated change) is greatly
reduced.Encapsulation: well-designed independent unitsPotential
Reuse of objects reduces time and cost
The Software ProcessA structured set of activities required to
develop a software
systemSpecification;Design;Validation;Evolution.A software process
model is an abstract representation of a process.It presents a
description of a process from some particular perspective.
Waterfall Model
Waterfall Model CharacteristicsThe classic life cycle - oldest
and most widely used paradigmActivities flow from one phase to
anotherIf there are corrections, return to a previous phase and
flow from there againMajor advantages: Good for planning and well
defined/repeated projects
Problems of Waterfall ModelReal projects often follow the
sequenceAll requirements may not be stated explicitly by
customerCustomer only sees the results after some timeDevelopers
are often delayed at certain phases
Rapid Application Development
(RAD)BusinessModelingDataModelingProcessModelingApplicationGenerationTesting
&Turnover
Team
#1BusinessModelingDataModelingProcessModelingApplicationGenerationTesting
&Turnover
Team #2
Time period
RAD CharacteristicsHigh-speed version of waterfall
modelPrimarily for information systems applicationsRequirements
well-understood, fully functional system produced in short timeThe
application modularized - major functions can be completed in 3
monthsSeparate teams complete the functions, then integrated as a
wholeRequires human resource and commitment
Scrum Agile Methodologies
Importance of Continual Planning, Testing, DocumentationAfter
customer has signed off on the specifications, continue to monitor
and adjust plan.Software must be fault-free as possible at all
times.At all times, documentation must be complete, correct and
up-to-date.personnel overturnincomplete implementationinaccurate
testingimpossible to maintain
ConclusionTips to Solve a problemAnalyse ProblemsSynthesize a
solutionUnderstand that requirements may change Must view quality
from several different perspectivesUse fundamental software
engineering conceptsKeep system boundary in mind
Thank you
EMBED Word.Picture.8
_958426784.unknown
