pertemuan 2-apbo-software-developmeng-processing

Apr 10, 2023

Software Development Process

E. Haodudin Nurkifli

Teknik Informatika

Universitas Ahmad DahlanKuliah 2 : Administrative dan Introduction

2 Oktober 2010

Eko AB – Analisis dan Perancangan Algoritma 2

Part 2Software Development Process


Systems vs. Software Development

Difficulties in Software Develoment

Software Development Life Cycle

User Involvement

Case Tools Support

Outline


Systems Development

Systems development is

concerned with all aspects

of computer-based systems

development including – hardware,

– software and

– Human activities

May not even include

software as part of the

solution


Software Development

Software development is focused soly on producing a

software system that will satisfy user requirement.

Software: computer programs and associated

documentation

• Software development may be considered as part of

systems development


The Main Players

Developers

– Those who will produce the system

End-users

– Those who may directly operate the system

Owners or sponsors - clients

– Those who commission the project, pay for it or

have the power to halt it


Sotware quality: whether the software “fits for purpose”, satisfies

all user requirements.

Example failures

– It might work, but dreadful to use (user)

– It is pretty, but does not do anything useful (user)

– Users and owners may not know how to ask for what they really want,

e.g. “We built what they said they wanted” (developer)

– Budget and time constraints often conflict with doing the job properly,

e.g. “There was not enough time to do it any better” (developer)

– Difficulties for the possession of blended skills, e.g. “Do not blame

me, I never done object-oriented analysis before” (developer)

Difficulties in Software Development


Productivity: the progress of the project, and the

resources (including time and money) that it consumes

along the way (much related to project management)

Example failures– A system that is promised but not delivered (user)

– It is no use delivering now, we need it last April (owner)

– Projects that overspend their budget (owner)

– Requirements drift, e.g. user changes their minds

frequently(develper)

– Implementation not feasible, e.g. we said it was impossible, but

no-one listened (developer)

Difficulties in Software Development

How to overcome them?


Software Development Process

Subdividing the process of software development into

different phases

Ease of management to produce appropriate quality

standard and to stay within the allocated budgest

Help to identify and allocate developers’ skills

appropriately, and thus improve the quality of the task

completion

Known as project life cycle model


Project Life Cycle

Two important precursor

phases are– Strategic Information Systems

Planning

– Business Modelling

Focus on organisation needs

They are not computational

Universially accepted for

commercially oriented

computer system development

Don´t blindly follow the path to

automation. The very first question is

whether or not you even need a

computer system...”


Generic Life Cycle Models

The Waterfall Model

Prototyping

Iterative and Incremental Development

The Unified Process Life Cycle


Waterfall Life Cycle

System System Engineering Engineering

Design Design

Code

Construction

Testing

Maintenance Maintenance

Analysis Requirements Analy sis

Code Installation

Requirements specificationFunctional specificationAcceptance test specifications

Unit test reportSub-system test reportSystem test reportAcceptance test reportCompleted system

Software architecture specificationSystem test specificationDesign specificationSub-system test specificationUnit test specification

Change requestsChange request report


Waterfall Life Cycle

• The traditional life cycle (TLC) for information

systems development.

• So called because of the difficulty of returning to

an earlier phase.

• The drawback of the waterfall model is the

difficulty of accommodating change after the

process is underway


TLC with Iteration

The cost of this form of iteration increases as the project progresses making it impractical and not effective


Problems with TLC

Real projects rarely follow such a simple sequential life

cycle

– Lapsed time between systems engineering and the

final installation is long

– Iterations are almost inevitable in real projects but are

expensive & problematic with the TLC

– Unresponsive to changes during project as iteration is

difficult

Therefore, this model is only appropriate when the

requirements are well-understood


Strengths of TLC

Provide a very structured way to system

development

Tasks in phases may be assigned to

specialized teams.

Project progress evaluated at the end of each

phase, and assessment made as to whether

the project should proceed


Prototyping Life Cycle

Initial analysis

Define objectives

Specify

Construct Evaluate Prototyping completed

• Not intended to deliver the final working system

• Quickly built up to explore some aspects of the system

• May be used as part of other iterative life cycle


Prototyping – Advantages

Early demonstrations of system functionality help

identify any misunderstandings between developer

and client

Client requirements that have been missed are

identified

Difficulties in the interface can be identified

The feasibility and usefulness of the system can be

tested, even though, by its very nature, the prototype

is incomplete


Prototyping – Problems:

The client may perceive the prototype as part of

the final system

The prototype may divert attention from

functional to solely interface issues

Prototyping requires significant user

involvement

Managing the prototyping life cycle requires

careful decision making


The Spiral Model

(Boehm, 1988)

Progress towards final system

Develop first increment

Develop next increment

Risk analysis based on initial

requirements Planning Risk analysis

User evaluation Software development

Risk analysis based on user

reaction to plan

Go, no-go decision Risk assessment

User evaluation

of increments

Further planning based on user

comments

Initial requirements

gathering and project planning

Incremental DevelopmentIncremental Development


Incremental Development

Iterative problem solving: repeats activities, each can be

viewed as a mini-project

Incremental delivery, either external or internal release

New release = new functionality + (improved) previous

release

Several approaches to structuring iterations

– Define and implement the key system functions

– Focus on one subsystem at a time

– Define by complexity or risk of certain components


The Unified Process System Development Life Cycle

Unified Process Life CycleUnified Process Life Cycle


Unified Process Life Cycle

Iteration


Unified Process Life Cycle

Captures many elements of best practice

The phases are:

– Inception is concerned with determining the scope

and purpose of the project;

– Elaboration focuses requirements capture and

determining the structure of the system;

– Construction's main aim is to build the software

system;

– Transition deals with product installation and rollout.


Predictive versus adaptive approaches to the SDLC

Choose Appropriate Life CycleChoose Appropriate Life Cycle

• TCL is highly predictive

• Prototyping, Spiral and UP life cycle models are highly

adaptive


User Involvement

As well as use appropriate process model,

user involvement and CASE tools support

also very improtant for project success

User’s can be involved at various levels

– As part of the development team (DSDM)

– Via a consultative approach

– In fact gathering


CASE Tools

CASE-Computer Aided Software Engineering, typically

provide a range of features including:– Model and technical support

• checks for syntactic correctness, consistency and completeness

• Layering, navigation to linked diagrams

• repository support, traceability

• report generation

• system simulation, performance analysis

– Software construction

• Code generation

• Reverse engineering


Reading

• Text Chapter 2, 3


Execises

1. Distinguish between client and user.

2. Define software quality.

3. What are the main difference between quality problems and

productivity problems?

4. Advantages and disadvantages of TLC, and how to overcome

the disadvantges?

5. Differences between prototyping and incremental

development?

6. Identify the ways and potential problems with user

involvement?

7. What do you think is meant by the term failure when it is

applied to an IS project?

pertemuan 2-apbo-software-developmeng-processing

Documents

software system

software fits

based systems development

system endusers

traditional life cycle

user requirements

generic life cycle models

project progresses