8-1 © prentice hall, 2007 topic 8: selecting the best alternative design strategy object-oriented...

8-1© Prentice Hall, 2007

Topic 8:Topic 8:Selecting the Best Alternative Selecting the Best Alternative

Design StrategyDesign Strategy

Object-Oriented Systems Analysis and Design

Joey F. George, Dinesh Batra,

Joseph S. Valacich, Jeffrey A. Hoffer

Topic 8 8-2© Prentice Hall, 2007

Chapter ObjectivesChapter Objectives

After studying this chapter you should be able to:– Describe the different sources of

software.– Assemble the various pieces of an

alternative design strategy.– Generate at least three alternative design

strategies for an information system.


Chapter Objectives Chapter Objectives (Continued)(Continued)

After studying this chapter you should be able to:– Select the best design strategy using

qualitative and quantitative methods.– Update a Baseline Project Plan (BPP)

based on the results of the analysis phase.


Deliverables for Design Deliverables for Design Strategy SelectionStrategy Selection

Why three? One for high-functionality high-cost solution, one for minimum functionality low-cost solution, and one for middle-of-the-road


Features are determined from requirements.

Constraints pertain to limitations on development efforts.


Generating a Design StrategyGenerating a Design Strategy

Divide requirements (obtained during requirements gathering and structuring) into sets of capabilities, categorized by level of necessity

Enumerate different potential implementation environments (hardware and system software platforms)

Propose different sourcing possibilities for obtaining the necessary software


What Is Outsourcing?What Is Outsourcing?

The practice of turning over responsibility of some or all of an organization’s information systems applications and operations to an outside firm

Can produce cost savings for the client, by leveraging the outsourcer’s economies of scale


Main Sources of SoftwareMain Sources of Software

– IT Service Firms– Packaged Software Providers– Custom Software Producers– Enterprise Solutions Software– Open Source Software– In-house Development


Information Technology Service Information Technology Service FirmsFirms

IBM is a leading IT service firm

Help develop custom information systems for internal use

Develop, host and run applications for clients

Provide other services


Package Software ProvidersPackage Software Providers

Microsoft is a leading package software provider

Packaged software is off-the-shelf software

Range from general-purpose to nrrow-niche focus

May be turnkey (unmodifiable) or modifiable


Custom Software ProducersCustom Software Producers

Firms like Accenture and CapGemini are leading custom software producers.

Consulting firms that develop software to meet the client’s specific requirements

Consulting firms are usually called when the client company does not have in-house expertise or manpower available to develop the system.


Enterprise Solutions SoftwareEnterprise Solutions Software

Enterprise Resource Planning (ERP) software – integrates individual traditional business functions modules enabling a single seamless transaction cut across functional boundaries

SAP AG is the leading vendor of ERP systems


Open Source SoftwareOpen Source Software Freely available Includes both final product and source code Developed by a community rather than a company Examples: mySql (database), Firefox (browser),

Linux (operating system) Profit potentials:

– Maintenance and service– Free version with fewer features, for-cost version with

more features


What Is an RFP?What Is an RFP?

Request for Proposal – a document provided to vendors to ask them to propose hardware and/or software products or services that will meet the requirements of an organization’s new information system

Based on vendor bids, analyst selects best candidates


Many factors go into selection of off-the-shelf software, many of which are relevant for other software purchases.

Vendor support and viability are always among the most important criteria.


In-house DevelopmentIn-house Development

If sufficient system development expertise with the chosen platform exists in-house, then some or all of the system can be developed by the organization’s own staff

Often, there are a variety of sources that are used, with in-house staff playing a role as well as consultants or ERP vendors


Validating Purchased Software Validating Purchased Software InformationInformation

Use a variety of information sources:– Vendor’s proposal– Running software through a series of tests– Feedback from other users of the vendor’s

product– Independent software testing services– Articles in trade publications


Hardware and System Software Hardware and System Software IssuesIssues

Reasons to stay with old platform– Lower cost installation– Familiarity of IS staff– Ease of integration with existing applications– Less need for data and software conversions


Hardware and System Software Hardware and System Software Issues (Continued)Issues (Continued)

Reasons to change to new platform– New components may not be compatible with

old platform– New platform provides opportunity for

organization to improve its technology holdings– New platform serves as impetus for significant

business process changes


Example: Pine Valley FurnitureExample: Pine Valley Furniture

• System requirements categorized into mandatory, essential, and desired capabilities

• Constraints established

• Low-end, high-end, and moderate design strategies are generated

• Weighted approach used to compare alternative design strategies


Server/Object Framework is the highest scoring alternative


3-Tier architecture is scalable, and consists of a Web server providing the interface to the Internet in the 1st tier, an application server running the business rules of the application in the 2nd tier, and the corporate databases in the 3rd tier


BPP goes through significant update as a result of design strategy generation and selection.

The System Description section is changed the most, and all sections are refined and altered.


Cost-benefit analysis goes through significant update and revision after selecting a design strategy.


Schedule estimation goes through significant update and revision after selecting a design strategy.


RecapRecap

After studying this chapter we learned to:– Describe software sources.– Assemble design strategies.– Generate three alternative design strategies.– Select the best design strategy qualitatively and

quantitatively.– Update a baseline project plan.

8-1 © prentice hall, 2007 topic 8: selecting the best alternative design strategy object-oriented...

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modifiable prentice

hoffer prentice hall

different sources of

custom software producersfirms

best design strategy

custom information systems

alternative design strategies

design strategy selectionwhy