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Chapter 2The Origins of Software

2011 by Prentice Hall: J.A.Hoffer et.al., Modern Systems Analysis & Design, 6th Edition 2/30

Content

Explain outsourcing

Describe different sources of softwareEvaluate commercial off-the-shelf (COTS)

software

Explain reuse and its role in softwaredevelopment

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1.Introduction

There are various sources of software for

organizations (build & buy)

There are criteria to evaluate software

from different sources

The impact of reuse on software

development

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2. Systems Acquisition

Outsourcing: turn over responsibility of

some or all of an organization's

information system (IS) applications andoperations to outside firms

Examples: a company that runs

payroll applications for clients

your applications at your site

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Reasons to outsource

Cost-effective

Take advantage of economies of scaleFree up internal resources

Reduce time to market

Increase process efficiencies

System development is a non-core

activity for the organization

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2.1 Sources of Software *

BuyInformation technology (IT) services firm

Packaged software producers

Enterprise-wide solutions: ERP

Application service providers (ASPs): Cloud C.

BuildOpen source software

In-house developers

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a) Information Technology Services Firms

Help companies develop custom

information systems for internal use

Develop, host, and run applications for

customers

Provide other services

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b) Packaged Software Producers

Serve many market segments

Ranges from broad-based packages (i.e.

general ledger) to niche packages (i.e.

day care management)

Runs on microcomputers to large

mainframes

Called off-the-shelf softwareat best meets 70 % of organizations needs

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9/30Copyright 2011 Pearson Education, Inc. Publishing as Prentice Hall

Packaged Software Producers (Cont.)

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Off-the-shelf Software

Figure 2-2 Microsoft Project

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c) Enterprise Solutions Software

Enterprise Resource Planning (ERP)

systems that integrate individual traditional

business functions into modules enabling asingle seamless transaction to cut across

functional boundaries

E.g. SAP, Oracle e-Business Suite 60%

of ERP market

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Enterprise Solutions Software (Cont.)

Figure 2-3 Functional areas supported by Oracles Business Suite

for small to medium businesses

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d) Application / Managed ServiceProvider: Cloud Computing

The provision of computing resources,including applications, over the Internet,

so customers do not have to invest in the

computing infrastructure needed to run

and maintain the resources

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e) Open Source Software

Freely available including source code

Developed by a community of interestedpeople

Performs the same functions as

commercial software

Examples: Linux, MySQL, Firefox

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f) In-House Development

If sufficient system development

expertise with the chosen platform exists

in-house, then some or all of the systemscan be developed by the organizations

own staffs

Hybrid solutions involving some

purchased and some in-house

components are common

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Sources of Software *

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2.2 Off-the-Shelf Software

Most common criteria for selecting

Cost: comparing the cost of developing the same in-house

system with the cost of purchasing or licensing the S/Wpackage

Functionality: refers to the tasks that the software can

perform and the mandatory, essential, and desired system

features

Vendor support: whether or how much support the vendor

can provide and at what cost

Viability of vendor: can the software adapt to change in

systems software and hardware

Cont.

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Most common criteria for selecting COTS

Flexibility: how easy it is to customize the software

Documentation: is the users manual and technical

documentation understandable and up-to-date

Response time: how long it takes the software

package to respond to the users requests in an

interactive session

Ease of installation: a measure of the difficulty of

loading the software and making it operational

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2.3 Validating Purchased Software

Information

Use a variety of information sources

Collect information from vendor

Vendors proposal

Software documentation

Technical marketing literature

Articles in trade publications

Testing & usage

Running software through a series of tests

Feedback from other users of the vendors product Independent software testing services

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Request For Proposal

Request For Proposal (RFP) is a document

provided to vendors to ask them to propose hardware

and system software that will meet the requirements

of a new system

Request For Quotation (RFQ)

A formal document: a single vendor that has been

determined as being able to supply that application

package and services

Based on vendor bids, analyst selects best candidates

Use a variety of information sources

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3. Reuse *

The use of previously written software

resources, especially objects and components,in new applications

Commonly applied to two different

development technologies

Object-oriented development

Component-based development

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Object-Oriented Development

Object class encapsulates data and

behavior of common organizationalentities (e.g. employee)

Object-oriented development reuse is

using object classes in more than one

application (e.g. employee)

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Component-based Development

Components can be as small as objects or

as large as pieces of software that handle

single business functions

Component-based development reuse is

the assembly of an application from many

different components at many different

levels of complexity and size (e.g.

currency conversion)

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Costs and Benefits of Reuse

FIGURE 2-5

Investments necessary to achieve reusable components

(Source: Royce, 1998, used by permission.)

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Approaches to Reuse

Ad-hoc: individuals are free to find or develop

reusable assets on their own Facilitated: developers are encouraged to practice

reuse

Managed: the development, sharing, and adoption of

reusable assets is mandated

Designed: mandating assets be designed for reuse as

they are being designed for specific applications

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Approaches to Reuse (Cont.)

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Summary

Explain outsourcing

Describe six different sources of

software

Discuss how to evaluate off-the-shelf

software

Explain reuse and its role in software

development

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Questions & Answers

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Quiz

1 Hardware manufacturers, packaged software

producers, custom software producers, enterprise

wide solutions, application server providers, and

________________ are sources of software.

2 Using _______________________, a firm can

integrate all parts of a business process in a

unified information system.

3 ___________ refers to the tasks the software canperform and the mandatory, essential, and desired

system features.

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Exercise:

1 Re-study SDLC in chapter 1

Explain the aspect of buying the commercial off-the-shelf software in SDLC.

Ref: Whitten & et.al. Systems Analysis and Design

Method, 7th edition, McGraw-Hill, 2007: Chapter 3

2 Describe & compare the various sources of SW

3 Explain reuse, its advantages & disadvantages