Chapter 11  2000 by Prentice Hall System Analysis and Design: Methodologies and Tools Uma Gupta Introduction to Information Systems

 2000 by Prentice Hall.11-2 Learning Objectives After studying this chapter, you will be able to:  Describe the systems development life cycle methodology and its limitations  Discuss the prototyping methodology  Explain end-user computing and the reasons for its growth  Outline situations in which companies should use off-the- shelf packages  Explain why outsourcing is a viable option for building information systems  Identify and discuss structured tools for system development

 2000 by Prentice Hall.11-3 System Development Life Cycle (SDLC)  A methodology to develop information systems that consists of these phases; system definition, analysis, design and programming, testing and implementation, and maintenance.

 2000 by Prentice Hall.11-4 Five Basic Components of a System Control Feedback InputProcessOutput Feedback THE SYSTEM’S ENVIRONMENT

 2000 by Prentice Hall.11-5 Five Phases of SDLC  System Definition  Describes what is being built and why it is being built –“What problems are we trying to solve?” –“What are the system’s objectives?”  System Analysis (three activities)  Understand the Problem  Feasibility Analysis  Establishing Functional Requirements

 2000 by Prentice Hall.11-6 Functional Requirements Provide Answers to the Following Questions  Who will use the system and for what purpose?  What are the specific information needs and expectations of the user?  Who will provide system input?  Who will receive system output?  Who will monitor system performance?  When should the system be delivered?  When will the system be updated?  What are the maintenance requirements?  What are the training requirements for this system?

 2000 by Prentice Hall.11-7 Five Phases of SDLC (cont.)  System Design and Programming (three activities)  Identify the appropriate technology to implement the system  Involve users in the development process from the beginning  Provide detailed specifications and show how these specifications help to meet system goals

 2000 by Prentice Hall.11-8 Five Phases of SDLC (cont.)  System Development  System programming is just one phase in the system development life cycle; it is highly complex, time-consuming and may take years to complete  System Testing (three types)  Unit testing  System testing  Acceptance testing

 2000 by Prentice Hall.11-9 Five Phases of SDLC (cont.)  System Implementation  There are four types of conversion or implementation strategies –Parallel conversion –Direct cutover –Pilot study –Phased conversion  System Maintenance  Maintenance makes up about half of the information systems activity in most companies

 2000 by Prentice Hall Four Implementation Strategies StrategyDescription Parallel conversion Old and new system run in parallel until new system becomes reliable Costly but safe approach Best suited to critical applications Old system is replaced with new system Less costly but more risky than parallel approach Best suited to noncritical applications Direct cutover

 2000 by Prentice Hall Four Implementation Strategies (cont.) Strategy Description Pilot study One department or unit serves as a testing ground Good for systems that are moderately critical New system is slowly phased into the operational environment Safe and conservative approach Well suited to critical systems Phased conversion

 2000 by Prentice Hall Prototyping  A development methodology that relies on prototypes, working or experimental models of a system. Also known as rapid application development.

 2000 by Prentice Hall Four Steps of Prototyping  Define the problem and identify system requirements  Build the initial prototype  Use the prototype to refine existing requirements  Revise and enhance the prototype

 2000 by Prentice Hall Off-the-Shelf Software Packages  Used by companies that do not have the resources or the inclination to build every part of their systems  Well suited for noncritical applications such as word processing, financial analysis, inventory control, scheduling project management, and employee benefits

 2000 by Prentice Hall The Percentage of Businesses that Use Off-the-Shelf versus Custom-Built Software Commercial package with minimum customization 49% N/A 2% Custom-built 26% Commercial package with extensive customization 23% Source: Computer Sciences Corp. CIO, June 1, 1997, p. 88.

 2000 by Prentice Hall Outsourcing  The process of relying on external experts to meet the in- house information needs of an organization.

 2000 by Prentice Hall Four Reasons Why Organizations Outsource Strategic Focus Economies of Scale Market Forces Technical Considerations

 2000 by Prentice Hall How Businesses Outsource IT Functions Different IT FunctionsOutsourcing Percentages PC desktops and networks35% Hardware support34% Application development30% None24% Systems operations22% Systems maintenance19% Other19% Call center management15%

 2000 by Prentice Hall Structured Tools  Tools and techniques used to develop a system that supports a top-down approach in which users study the system starting from the highest level of detail and move to the lowest.

 2000 by Prentice Hall Tools Used to Analyze and Design Systems  Context Diagram  Graphically depicts the overall system that is being built  Data Flow Diagrams  Provides a closer look at each subsystem that makes up the system  The DFD shows three items –How data flow in the system (inputs and outputs) –The processes that convert input into output –Where the data are stored in the system (data stores)

 2000 by Prentice Hall Tools Used to Capture and Represent System Data  An entity relationship diagram (ERD) is a graphical depiction that identifies the entities of a system and their relationships.

 2000 by Prentice Hall Five Steps in Creating an ERD Step One: Developers and users work together as a team to identify the different entities in the system. Step Two: Establish the nature and scope of the relationship between the different entities identified in the previous step. Are the relationships one-to-one (1-1), one-to-many (1-M), or many-to-many (M-M)? Step Three: Describe each entity using a set of data elements Step Four: Graphically depict the data associated with each entity and the type of relationship between different entities. Step Five: Check that no entity is missing and that the relationships between different entities are accurately portrayed.

 2000 by Prentice Hall Tools Used to Capture and Represent Processes  Structured programming is a tool that shows the processes that convert data into information.

 2000 by Prentice Hall Tools Used to Capture and Represent Processes (cont.)  A structure chart is a graphical systems tool that show the hierarchy of software modules and the relationship among different modules.

 2000 by Prentice Hall Tools Used to Capture and Represent Processes (cont.)  A system flowchart is a chart that shows how data flows in an information system. It also shows the processes, the sequence of the processes, relationships between the processes, and the data required for each process.

 2000 by Prentice Hall Tools Used to Capture and Represent Processes (cont.)  Decision tables are rules that capture the logic in system processes using a set of conditions (IF clauses) and actions (THEN clauses) shown in the form of a table.

 2000 by Prentice Hall Tools Used to Capture and Represent Processes (cont.)  A decision tree is a graphical representation of steps used to solve a problem.

 2000 by Prentice Hall Tools Used to Convert Program Specifications into Code  Structured english (pseudocode) is a code that converts program specifications written in English sentences into simple, easy-to- understand English phrases.

 2000 by Prentice Hall Business Guidelines for System Development Success  Every Information System Is a Business System  Many IS projects fail because organizations view them as technology projects, not business projects  The Business of IS Departments Is Change  As the environment around the system changes, the system must adapt  Systems Development Is a Venture, Not and End in Itself

 2000 by Prentice Hall Business Guidelines for System Development Success (cont.)  One Size Doesn’t Fit All—Especially in a Global Environment  Running into political, cultural, and technical glitches in global system implementation is very common  Build the Development Team  IS managers must build a culture that fosters creativity, innovation, and teamwork  It’s All about Users  What really lies behind a successful system is not just hardware and software but more important, people