systems analysis & design sixth edition chapter 5 development strategies
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Systems Analysis & Design
Sixth Edition
Chapter 5
Development Strategies
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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
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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
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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
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The Impact of the Internet
● 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
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The Impact of the Internet
● 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
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The Impact of the Internet
● 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
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The Impact of the Internet
● 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
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The Impact of the Internet
● 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
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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
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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
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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
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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
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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
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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”
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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
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In-House Software Development Options
● 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
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In-House Software Development Options
● 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
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In-House Software Development Options
● 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
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In-House Software Development Options
● 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
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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
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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
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The Software Acquisition Process
● 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
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The Software Acquisition Process
● 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
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The Software Acquisition Process
● 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
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The Software Acquisition Process
● 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
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The Software Acquisition Process
● 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
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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
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Completion of Systems Analysis Tasks
● 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
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Completion of Systems Analysis Tasks
● 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
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Completion of Systems Analysis Tasks
● 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
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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
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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
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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
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Systems Design Guidelines
● Systems Design Objectives– The goal of systems design is to build a
system that is effective, reliable, and maintainable
– Some considerations examples
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Systems Design Guidelines
● 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
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Systems Design Guidelines
● 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
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Prototyping
● Prototyping produces an early, rapidly constructed working version of the proposed information system, called a prototype
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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
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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
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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