chapter 6_part i

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System Design

Chapter 6

Design Strategy, System Input &User Interface, File and Databases



System Design

Chapter 6

PART I: Design Strategy



Outcome

Describe different sources of software

Learn to assemble the various pieces of an

alternative design strategy Learn how to generate at least three

alternative design strategies

Discuss selecting the best design strategy

using both qualitative and quantitativemethods



Design Strategy

Two basic steps1. Generate a comprehensive set of alternative design

strategies

2. Select the one design strategy that is most likely to result in

the desired information system Process

Divide requirements into different sets of capabilities

Determine different potential implementation environmentsthat could be used to deliver the different sets of capabilities

Propose different ways to source or acquire the varioussets of capabilities for the different implementationenvironments



Design Strategy

Deliverables

1. At least three substantially different system design

strategies for building the replacement information

system

2. A design strategy judged most likely to lead to the

most desirable information system

3. A Baseline Project Plan (BPP) for turning the

most likely design strategy into a working

information system



Generating Alternative Design

Strategies

Best to generate three alternatives

Low-end

Provides all required functionality users demand with a

system that is minimally different from the currentsystem

High-end

Solves problem in question and provides many extra

features users desire Midrange

Compromise of features of high-end alternative with

frugality of low-end alternative



Issues to Consider in Generating

Alternatives

Outsourcing The practice of turning over responsibility of some to all of

an organization¶s information systems applications andoperations to an outside firm

Can provide a cost effective solution

Sources of Software Hardware manufacturers

Packaged software producers

Custom software producers Enterprise solution software

Application Service Providers

In-house development



Criteria for Choosing

Off-the-Shelf Software

Cost In-House versus purchased

Functionality Mandatory, essential and desired features

Vendor Support Installation

Training

Technical Support

Viability of Vendor



Criteria for Choosing

Off-the-Shelf Software

Flexibility

Ease of customization

Documentation User documentation

Technical documentation

Response Time

Ease of Installation



Hardware and Software Issues

Existing Platform Lower costs

Information system staff is familiar with operation

and maintenance Increased odds of

successfully integratingsystem with existingapplications

No added costs of converting old systemsto new platform or transferring data

New Hardwar e andSystem Softwar e

Some softwarecomponents will only runon new platform

Developing system for new platform givesorganization opportunityto upgrade technology

holdings New requirements mayallow organization toradically change itscomputing operations



Implementation and Organizational

Issues.

Implementation Issues

Technical and social aspects of implementation need to

be addressed

Training

Disruption of work

Organizational Issues

Overall cost and availability of funding

Management support

User acceptance



Updating the Baseline Project Plan

(BPP)

The Baseline Project Plan (BPP) wasdeveloped during project initiation andplanning

Baseline Project Plan (BPP) can be used asan outline of a status report at analysis phase

Schedule will be updated to reflect actualactivities and durations

An oral presentation of project status istypically made at this phase



Summary

Sources of Software

Identifying requirements and constraints

Generating alternative design strategies Selecting the best design strategy

Updating a Baseline Project Plan (BPP)

Selecting the best design strategy for Internetapplications

chapter 6_part i

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