systems analysis & design sixth edition chapter 5 development strategies

Systems Analysis & Design

Sixth Edition

Chapter 5

Development Strategies

2222

Introduction

● Chapter 5 describes the remaining activities in the systems analysis phase

● The chapter also describes the transition to systems design, prototyping, and systems design guidelines

3333

Development Strategies Overview

● Selecting the best development path is an important decision that requires companies to consider three key topics– The impact of the Internet– Software outsourcing options– In-house software development

alternatives

4444

The Impact of the Internet

● The Internet has triggered enormous changes in business methods and operations, and software acquisition is no exception

● This section examines a trend that views software as a service, the changing market-place for software, and how Web-based development compares to traditional methods

5555


● Software as a Service– The Software and Information Industry

Association (SIIA) is an industry group that focuses on the digital economy

– SIIA believes that the concept of software as a service is redefining the way that companies develop and deploy their information systems

6666


● The Changing Software Marketplace– In the traditional model, software vendors

develop and sell application packages to customers

– In addition to traditional vendors, the marketplace now includes many forms of outsourcing, including application service providers and firms that offer Internet business services

7777


● The Impact of the Internet on Systems Development– Developers will focus on Web-based

application development, where the Web becomes an integral part of the application rather than just a communication channel

8888


● The Impact of the Internet on Systems Development– Traditional development

• Systems design is influenced by compatibility issues

• Systems are designed to run on local and wide-area company networks

• Web-based features are treated as enhancements rather than core elements of the design

9999


● The Impact of the Internet on Systems Development– Web-based development

• Internet-based development treats the Web as the platform, rather than just a communication channel

• Web-based software usually requires additional layers, called middleware

10101010

Outsourcing

● Can refer to relatively minor programming tasks, the rental of software from a service provider, the outsourcing of a basic business process (often called business process outsourcing, or BPO), or the handling of a company’s entire IT function

11111111

Outsourcing

● The Growth of Outsourcing– Traditionally, firms outsourced IT tasks as

a way of controlling costs and dealing with rapid technological change

– Outsourcing has become part of an overall IT strategy for many organizations

12121212

Outsourcing

● The Growth of Outsourcing– A firm that offers outsourcing solutions is

called a service provider– Application service providers (ASP)– Internet business services (IBS)

• Also called managed hosting

13131313

Outsourcing

● Outsourcing Fees– A fixed fee model uses a set fee based

on a specified level of service and user support

– A subscription model has a variable fee based on the number of users or workstations that have access to the application

– A usage model or transaction model charges a variable fee based on the volume of transactions or operations performed by the application

14141414

Outsourcing

● Outsourcing Issues and Concerns– Mission-critical IT systems should be out-

sourced only if the result is a cost-attractive, reliable, business solution that fits the company’s long-term business strategy

– Outsourcing can be especially attractive to a company whose volume fluctuates widely, Ex. 處理全國考試業務

15151515

Outsourcing

● Offshore Outsourcing– Offshore outsourcing – global outsourcing– Many firms are sending IT work overseas

at an increasing rate– Gartner, a leading IT research and

consulting firm, predicts that by 2005 one in 10 IT jobs at U.S. IT companies and one in 20 at non-IT companies will move offshore

– Read “The World Is Flat”

16161616

In-House Software Development Options

● A company can choose to develop its own systems, or purchase, possibly customize, and implement a software package

● The most important consideration is total cost of ownership (TCO)

● Companies also develop user applications designed around commercial software packages, e.g. Excel, Word

17171717


● Make or Buy Decision (Fig. 5-9, p. 205) – The choice between developing versus

purchasing software often is called a make or buy, or build or buy decision

– Companies that develop software for sale are called software vendors

– Value-added reseller (VAR): add custom features on a commercial package

– Horizontal application– Vertical application

18181818


● Reasons for Developing Software In-House– Satisfy unique business requirements– Minimize changes in business procedures

and policies– Meet constraints of existing systems– Meet constraints of existing technology– Develop internal resources and

capabilities

19191919


● Reasons for Purchasing a Software Package– Lower costs– Requires less time to implement– Proven reliability and performance

benchmarks– Requires less technical development staff– Future upgrades provided by the vendor– Input from other companies

20202020


● Customizing a Software Package1. You can purchase a basic package that

vendors will customize to suit your needs

2. You can negotiate directly with the software vendor to make enhancements to meet your needs by paying for the changes

3. You can purchase the package and make your own modifications, if this is permissible under the terms of the software license

21212121

Role of the Systems Analyst

● When selecting hardware and software, systems analysts often work as an evaluation and selection team

● The primary objective of the evaluation and selection team is to eliminate system alternatives that will not work, rank the system alternatives that will work, and present the viable alternatives to management for a final decision

22222222

The Software Acquisition Process

● Step 1: Evaluate the Information System Requirements– Prepare a request for proposal or quotation

• Request for proposal (RFP) 系統建議邀約 , P. 213-215

• Evaluation model, P. 216• Request for quotation (RFQ) 報價書邀約 : 已知要買的東西

23232323


● Step 2: Identify Potential Vendors or Outsourcing Options– The Internet is a primary marketplace– Another approach is to work with a

consulting firm– Another resource is the Internet bulletin

board system that contains thousands of forums, called newsgroups

24242424


● Step 3: Evaluate the Alternatives– Existing users– Application testing– Benchmarking – benchmark

testing: ex. Testing the time needed to post 1,000 sales transactions.

– Match each package against the RFP features and rank the choices

25252525


● Step 4: Perform Cost-Benefit Analysis– Identify and calculate TCO for each option

you are considering– When you purchase software, what you

are buying is a software license– If you purchase a software package,

consider a supplemental maintenance agreement

26262626


● Step 5: Prepare a Recommendation– You should prepare a recommendation

that evaluates and describes the alternatives, together with the costs, benefits, advantages, and disadvantages of each option

– At this point, you may be required to submit a formal system requirements document and deliver a presentation

27272727


● Step 6: Implement the Solution– Implementation tasks will depend on the

solution selected– Before the new software becomes

operational, you must complete all implementation steps, including loading, configuring, and testing the software; training users; and converting data files to the new system’s format

28282828

Completion of Systems Analysis Tasks

● System Requirements Document– The system requirements document,

or software requirements specification, contains the requirements for the new system, describes the alternatives that were considered, and makes a specific recommendation to management

– Like a contract– Format and organize it so it is easy to

read and use

29292929


● Presentation to Management– Begin your presentation with a brief

overview of the purpose and primary objectives of the system project, the objectives of this presentation, and what decisions need to made

– Summarize the primary viable alternatives. For each alternative, describe the costs, advantages, and disadvantages

30303030


● Presentation to Management– Explain why the evaluation and selection

team chose the recommended alternative– Allow time for discussion and for questions

and answers– Obtain a final decision from management

or agree on a timetable for the next step in the process

31313131


● Presentation to Management– Based on their decision, your next task

will be one of the following1. Implement an outsourcing alternative2. Develop an in-house system3. Purchase or customize a software package4. Perform additional systems analysis work5. Stop all further work

32323232

The Transition to Systems Design

● If management decides to develop the system in-house, then the transition to the systems design phase begins

● Preparing for Systems Design Tasks– It is essential to have an accurate and

understandable system requirements document

33333333

The Transition to Systems Design

● The Relationship between Logical and Physical Design– The logical design defines the functions

and features of the system and the relationships among its components

– The physical design of an information system is a plan for the actual implementation of the system

34343434

Systems Design Guidelines

● The systems analyst must understand the logical design of the system before beginning the physical design of any one component– Data design– User interface– Systems design specification

35353535


● Systems Design Objectives– The goal of systems design is to build a

system that is effective, reliable, and maintainable

– Some considerations examples

36363636


● System Design Objectives– User Considerations– Data Considerations

• Data should be entered into the system where and when it occurs because delays cause data errors

• Data should be verified when entered to catch errors immediately

• Automated methods of data entry should be used whenever possible

• Access for data entry should be controlled and all entries or changes to critical data values should be reported – audit trails

37373737


● System Design Objectives– Data Considerations

• Data should be entered into a system only once• Data duplication should be avoided

– Architecture considerations• Use a modular design• Design modules that perform a single function

are easier to understand, implement, and maintain

38383838

Prototyping

● Prototyping produces an early, rapidly constructed working version of the proposed information system, called a prototype

39393939

Prototyping

● Prototyping Methods– Prototyping offers many benefits

• Users and systems developers can avoid misunderstandings

• Managers can evaluate a working model more effectively than a paper specification

– Consider potential problems• The rapid pace of development can create

quality problems• In very complex systems, the prototype

becomes unwieldy and difficult to manage

40404040

Prototyping

● Prototyping Tools– Systems analysts can use powerful tools

to develop prototypes• CASE tools• Application generators• Report generators• Screen generators• Fourth-generation language (4GL)• Fourth-generation environment

41414141

Prototyping

● Limitations of Prototypes– A prototype is a functioning system, but it

is less efficient than a fully developed system

– Systems developers can upgrade the prototype into the final information system by adding the necessary capability

– Otherwise, the prototype is discarded

systems analysis & design sixth edition chapter 5 development strategies

Documents

outsourcing outsourcing

development strategies

design slide

web based development

systems development

growth of outsourcing

software vendors

outsourcing solutions