Systems Analysis Design 5 th Edition Chapter

Systems Analysis & Design 5 th Edition Chapter 5 ● Development Strategies

Introduction ● Chapter 5 describes the remaining activities in the systems analysis phase ● The chapter also describes the transition to systems design, prototyping, design guidelines 2

Development Strategies Overview ● Selecting the best development path is an important decision that requires companies to consider three key issues – Web-based software trends – Software outsourcing options – In-house software development alternatives 3

Web-Based Software Trends ● 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 4

Web-Based Software Trends ● 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 5

Web-Based Software Trends ● 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 6

Web-Based Software Trends ● The Impact of the Internet on Systems Development – Developers will focus on Web-based application development, which builds the Web into the application, rather than the other way around • IBM’s Web. Sphere • Microsoft’s. NET 7

Web-Based Software Trends ● The Impact of the Internet on Systems Development – Traditional development • System 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 8

Web-Based Software Trends ● The Impact of the Internet on Systems Development – Web-based development • Systems are developed and delivered in an Internetbased framework such as. NET or Web. Sphere • Internet-based development treats the Web as the platform, rather than just a communication channel • Web-based software usually requires additional layers, called middleware 9

Software Outsourcing Options ● Outsourcing is the transfer of information systems development, operation, or maintenance to an outside firm that provides these services, for a fee, on a temporary or long-term basis ● Can refer to relatively minor programming tasks or the handling of a company’s entire IT function 10

Software Outsourcing Options ● The Growth of Outsourcing – Traditionally, firms outsourced IT tasks as a way of controlling costs and dealing with rapid technological change – Today, outsourcing is a vital business issue that shapes a company’s overall IT strategy – the most important factor is the potential saving in operating costs 11

Software Outsourcing Options ● 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 12

Software Outsourcing Options ● 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 – A usage model or transaction model charges a variable fee based on the volume of transactions or operations 13

Software Outsourcing Options ● Outsourcing Issues and Concerns – Mission-critical IT systems should be outsourced only if the result is a cost-attractive, reliable, business solution that fits the company’s long-term business strategy 14

Software Outsourcing Options ● Outsourcing Issues and Concerns – A company must plan outsourcing carefully to avoid lost revenue, added expenses, and potential litigation – The solution can be only as good as the outsourcing firm that provides the service – A major disadvantage of outsourcing is that it raises employee concerns about job security 15

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 16

In-House Software Development Options ● Make or Buy Decision – The choice between developing versus purchasing software often is called a make or buy, or build or buy decision – The company’s IT department makes, builds, and develops in-house software – A software package is obtained from a vendor or application service provider. 17

In-House Software Development Options ● Make or Buy Decision – Companies that develop software for sale are called software vendors – Value-added reseller (VAR) • A firm that enhances a commercial package by adding custom features and configuring it for a particular industry – Vertical application – Horizontal application 18

In-House Software Development Options ● 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 19

In-House Software Development Options ● 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 20

In-House Software Development Options ● Customizing a Software Package 1. 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 21

In-House Software Development Options ● Creating User Applications – A user application utilizes standard business software – Help desk or information center (IC) – Screen generators – Report generators – Read-only properties 22

Role of the Systems Analyst ● When selecting hardware and software, systems analysts often work as an evaluation and selection team ● A team approach ensures that critical factors are not overlooked and that a sound choice is made 23

Role of the Systems Analyst ● 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 24

A Software Acquisition Example ● Step 1: Evaluate the Information System Requirements – – Identify key features Consider network and web-related issues Estimate volume and future growth Specify hardware, software, or personnel constraints – Prepare a request for proposal or quotation • Request for proposal (RFP)建議書邀約 • Evaluation model • Request for quotation (RFQ)報價書邀約 25

A Software Acquisition Example ● 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 systems that contains thousands of forums, called newsgroups 26

A Software Acquisition Example ● Step 3: Evaluate the Alternatives – – Existing users Application testing Benchmarks 標竿測試 Match each package against the RFP features and rank the choices 27

A Software Acquisition Example ● 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 maintenance agreement 28

A Software Acquisition Example ● Step 5: Prepare a Recommendation – You should prepare a recommendation that contains your recommendation and lists 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 29

A Software Acquisition Example ● 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 30

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 31

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 – Summarize the primary viable alternatives. For each alternative, describe the costs, advantages, and disadvantages 32

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 33

Completion of Systems Analysis Tasks ● Presentation to Management – Based on their decision, your next task will be one of the following 1. 2. 3. 4. 5. Implement an outsourcing alternative Develop an in-house system Purchase or customize a software package Perform additional systems analysis work Stop all further work 34

The Transition to System 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 35

The Transition to System 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 36

Systems Design Guidelines ● System Design Objectives – The goal of systems design is to build a system that is effective, reliable, and maintainable – A system is reliable if it adequately handles errors – A system is maintainable if it is well designed, flexible, and developed with future modifications in mind 37

Systems Design Guidelines ● System Design Objectives – User considerations • Carefully consider any point where users receive output from, or provide input to, the system • Anticipate future needs of the users, the system, and the organization • Provide flexibility • Parameter, default – Data Considerations • Data should be entered into the system where and when it occurs because delays cause errors • Data should be verified when entered to catch errors immediately 38

Systems Design Guidelines ● System Design Objectives – Data Considerations • 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 • Every instance of entry and change to data should be logged • Data should be entered into a system only once • Data duplication should be avoided 39

Systems Design Guidelines ● System Design Objectives – Architecture considerations • Use a modular design • Design modules that perform a single function are easier to understand, implement, and maintain 40

Prototyping ● Prototyping produces an early, rapidly constructed working version of the proposed information system, called a prototype ● Prototyping allows users to examine a model that accurately represents system outputs, interfaces, and processes 41

Prototyping ● Prototyping Methods –System prototyping –Design prototyping 42

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 – Also consider potential problems • The rapid pace of development can create quality problems • In very complex systems, the prototype becomes unwieldy and difficult to manage 43

Prototyping ● Prototyping Tools – Systems analysts can use powerful tools to develop prototypes • • • CASE tools Application generators Report generators Screen generators Fourth-generation languages (4 GLs) 44

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 45