Session 1 - Software Development Process1

8/14/2019 Session 1 - Software Development Process1

1/40

SoftwareSoftwareDevelopmentDevelopment

ProcessProcess


2/40

Session Objectives

Introduction to SDP

Understanding Quality

Understanding ProcessUnderstanding Life Cycle Models

Choosing a Process

Conclusion


3/40

Programming in Small

Individual Effort

Not rigorously tested

Used by the developer only

Circus in programming Language

Intellectual Exercise

No Documentation

Developer Maintenance


4/40

1.Team Effort

2.Use of methodology

3.Documentation

4.Schedule/Cost Control

5.Quality Assurance

6.Used by lay User

7.Planning

8.Reuse

Programming in Large

9.Use of SoftwareTools

10.Conformance to

standards 11. Very Likely to be

commercial

12. Non-Developer

maintenance 13.Change

Management

14.Version Control

15.Subject To Risk


5/40

Programming:Small Vs Large

1)Writing a program 2)Creatingan airline

that sorts a list of ticketreservation

strings an application system, a

browserthat stores the names like

Internet

of friends and their Explorer.


6/40

The Myths And Facts

MYTH: There are 10 steps toSuccessful software development

FACT: Software development is about

projects

MYTH: Software development is about

technologyFACT: Software development is about

Technology. It is also about people,methodology and process.


7/40

The Myths And Facts

MYTH: Software Development is aboutwriting code.

FACT: Writing code is the part of

software development -perhaps theeasiest part to do

MYTH: Most software projects aresuccessful.

FACT: 32% of projects terminatebefore delivery and only 11% arecompleted on budget. Of the remaining


8/40

2004 Third Quarter Research

Report

This year results show that 295 of allprojects succeeded (delivered on time,on budget, with required features and

functions); 53% are challenged (late,over budget and/or with less than therequired features and functions); and18% have failed (cancelled prior to

completion or delivered and neverused).

Courtesy: The Standish Group


9/40

Common dangerous Attitudes

Documenting and reviewing arewaste of time.

The customer should accept whatwe deliver.

Standards constrain and limit

creativityI/we should build everything

In any case, we have disclaimers

rather than guaranties/warranties


10/40

What is a successful software

project?

A project that meets or exceedscustomer expectations in terms offeatures, quality, cost andschedule.

And adds value, monetary orother, to the developmentcompany.


11/40

What is Engineering

Approach?

Disciplined Problem Solving

Analysis of a problem.

Product SpecificationSub-assemblies.

Prototypes.

Reuse.


12/40

Software Engineering

Term Coined in 1967 andendorsed by NATO conference in1968

Relatively young in comparison to

other engineering disciplines.


13/40

Software

Engineering:Definition

A Systematic Approach to theDevelopment, Operation, Maintenance

and Retirement of Software,

Where Software is ComputerPrograms, Procedures, Rules and

Associated Documents and datapertaining to the Operation of aComputer System.

- IEEE


14/40

Similarity in software and

hardware

Phases

Methodology

ActivitiesStandards

Tools


15/40

Uniqueness of Software

Not manufactured in the classicalsense.

Similarities exist between software and

hardware manufacture but- The relationship between people

applied and

work accomplished is different.

- The manufacturing phase forhardware can

introduce quality problems that are

nonexistent in software production.-


16/40

Uniqueness of Software

Usually custom- built.

The difference between generic

and bespoke software.Does not wear-out.

Absence of physical laws

governing the behavior ofsoftware.

It is invisible.


17/40

Aspects of Software projects

Team effort: Any large developmenteffort requires the services of a team ofspecialists.

Methodology: two types ofmethodologies, 'procedure oriented

methodolgies' and 'object orientedmethodologies'.

Documentation: Clear andunambiguous documentation of the

artifacts of the development process arecritical for the success of the softwareproject.

Planning: development takes placeagainst a client's requirements so thewhole effort is to be well planned to


18/40


Lay user: Most of the time, thesesoftware packages will be used by non-computer savvy users. Hence the

software has to be highly robust.Software tools: Documentation isimportant for the success of a softwareproject. There are tools known as

Computer Aided Software Engineering(CASE) tools which simplify the processof documentation.

Conformance to standards: We

need to follow certain standards toensure clear and unambi uous


19/40


Non-developer maintenance:Software lives for a long time. Thedevelopment team, may not.

Change management: Whenever achange has to be made, it is necessaryto analyse its impact on various partsof the software.

Version control: Once changes are

made to the software, the user shouldget the right copy of the software.Failures should roll back to theprevious versions.

Subject to risks: Any large effort issubject to risks. Eg: skills, technology,


20/40

Session Objectives

Introduction to SDP



Choosing a Process

Conclusion


21/40

Software Quality

Goal of any software developmentprocess is to produce high qualitysoftware.

Software quality has beenvariously defined as:

Fitness for purpose

Zero defects

The ability of the software to meetcustomer's stated and implied needs


22/40

Software Attributes for Quality

Measurement

Important attributes used tomeasure software quality are:

Correctness Software should meet the

customer's needsRobustness Software must alwaysbehave in an expected manner, evenwhen unexpected inputs are given

Usability Ease of use. A software witha graphical user interface isconsidered more user-friendly thanone without it

Portability The ease with which


23/40


Measurement

Efficiency Optimal resource(memory & execution time)utilization

Maintainability Ease with whichsoftware can be modified

Reliability The probability of the

software giving consistentresults over a period of time

Flexibility Ease with which

software can be adapted for use


24/40


Measurement

Security Prevention ofunauthorised access

Interoperabilty The ability of the

software to integrate withexisting systems

Performance The ability of the

software to deliver the outputswith in the given constraints liketime, accuracy, memory usage


25/40

Attributes & Realization

Correctness is the most importantattribute.

The other attributes may be

present in varying degrees.Eg: it is an expensive proposition tomake a software 100% reliable and itis not required in all contexts.

Some of the attributes conflictwith each other.Eg: portability and efficiency couldconflict with each other.

In practice there will always be a


26/40

Session Objectives

Introduction to SDP



Choosing a Process

Conclusion


27/40

Exercise - 100% Inspection

Start Reading the passage and count theoccurrence of Fs

The Bangalore Metro Rail concept, so far onlyon demo videos, is finally on its way to

becoming a reality. The 33 kilometre route, ofwhich 26.3 kilometres will be elevated and6.7 kilometres will be underground, isexpected to be completed by December2011. The first phase charting a seven

kilometre route will be completed by 2009.The project, which is expected to cost awhopping Rs 6,395 crore, has multiplefinancial partners. These include theGovernment of India with an equity of 25 percent, the government of Karnataka with an


28/40

Exercise - 100% Inspection

Defining a process

Circle the Fs as you read themand at the end of each line count

the circles and enter it againstthe line

Repeat for each line

Count all the counts entered atthe end of each line for total.


29/40

The Process

The Bangalore Metro Rail concept, so far onlyon demo videos, is finally on its way tobecoming a reality. The 33 kilometre route, ofwhich 26.3 kilometres will be elevated and

6.7 kilometres will be underground, isexpected to be completed by December2011. The first phase charting a sevenkilometre route will be completed by 2009.The project, which is expected to cost a

whopping Rs 6,395 crore, has multiplefinancial partners. These include theGovernment of India with an equity of 25 percent, the government of Karnataka with anequity of 30 per cent and the Japan Bank of

International Cooperation with its equity

- 1- 1- 1- 0

- 1- 0- 1- 2- 2

- 1- 2- 1- 0- 2


30/40

What is a Process?

A Process is a series of definable,repeatable, and measurable tasksleading to a useful result. The benefits

of a well defined process are numerous.It provides visibility into a project.

It helps developers to weed out faults at thepoint of introduction. This avoids cascading

of faults into later phasesIt helps to organize workflow and outputs tomaximize resource utilization

It defines everybody's roles and

responsibilities clearly.


31/40

SDP - Phases

The generic phases that are normally used ina software development process are:

Analysis: user needs are gathered and convertedinto software requirements. - should answer the

question: what is to be done to meet user needs?Design: answers the question: How to meet theuser needs? - In this phase we determineorganisation of various modules in the softwaresystem

Construction: Coding is the main activity in this

phaseTesting: There are three categories of testing: unittesting, integration testing, and system testing.There are two types of testing: Black box testingand White box testing. Black box testing focuses ongenerating test cases based on requirements.White box testing focuses on generating test cases


32/40

Session Objectives

Introduction to SDP



Choosing a Process

Conclusion


33/40

Waterfall model

Sequential model, alsoknown as water fall model:

Analysis

Design

Development

Testing

Implementation


34/40

Waterfall Model

sequence of steps (phases).

requires a phase is complete

before the next phase is started.helps in contract finalisation withreference to delivery and paymentschedules.

Is difficult to use this model as itis, because of the uncertainity inthe software requirements.


35/40

Prototyping

Prototyping - working version of thesoftware is built early in the project life.

Throw away prototypeEvolutionary prototype

Throw away prototyping modelunderstand the requirements and solution

methodologies better.essence is speed.

ad-hoc and quick development approachwith no thought to quality

once the objective is met, the code isdiscarded and fresh development is


36/40

Prototyping

Evolutionary prototyping modelrequirements are prioritisedcode is developed for the most importantrequirements first, with an eye on quality.

Software is continuously refined andexpanded with feedback from the client.advantage of prototyping is that the clientgets a feel of the product early in theproject life cycle.

As can be seen, evolutionaryprototyping is an iterative model. Sucha model can be characterised by doinga little analysis, design, code, test and

repeat the process till the product iscomplete.


37/40

Spiral ModelSpiral model - Another iteartivemodel

Is like a framework, adapted tospecific projects.


38/40

Spiral Model

best mix of other approaches

focusses on eliminating errors and

unattractive alternatives early.Important feature of this model isstress on risk analysis.

This model is best suited forprojects, which involve newtechnology development. Riskanalysis expertise is most criticalfor such ro ects.


39/40

ETVX model

Introduced by IBM during the 80's todocument their processes.

'E' stands for the entry criteria to be satisfied fortasks to be performed

'T' is the set of tasks to be performed'V' stands for the verification & validation process toensure that the right tasks are performed

'X' stands for the exit criteria or the outputs of thetasks. If an activity fails in the validation check,either corrective action is taken or a rework isordered.

It can be used in any development process.Each phase in the process can be consideredas an activity and structured using the ETVX

model.If re uired the tasks can be further


40/40

ETVX Model