Software System Analysis & Design

Course

Chapter 1

The Systems Development Environment

Essentials of Systems Analysis and Design 3rd Edition

Joseph S. Valacich , Joey F. George , Jeffrey A. Hoffer

System Analysis & Design Course

Learning ObjectivesDefine information systems analysis and design.

Discuss the modern approach to systems analysis and design that combines both process and data views of systems.

Describe the role of the systems analyst in information systems development.

Describe the different sources of software.

Describe three types of information systems: Transaction Processing Systems (TPS)

Management Information Systems (MIS)

Decision Support Systems (DSS).

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Learning Objectives (continued)

Describe the information systems development life cycle (SDLC).

Discuss alternatives to the systems development life cycle, including a description of the role of computer aided software engineering (CASE) tools in systems development.

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What is Information Systems Analysis and Design?

• A method used by companies to create andmaintain systems that perform basic businessfunctions such as keeping track of customer namesand addresses, processing orders, and payingemployees.

• Main goal is to improve employee efficiency byapplying software solutions to key businesstasks

• A structured approach must be used in order toensure success

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What is Information Systems Analysis and Design?

• Systems Analyst performs analysis and design based upon:– Understanding of organization’s objectives,

structure and processes

– Knowledge of how to exploit information technology for advantage

• Fig 1-1 illustrates the Systems Development Life Cycle, a four-

phased approach used throughout this text.

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Systems Analysis and Design: Core Concepts

• Major goal: to improve organizational systems by developing or acquiring application software and training employees in its use

• Application software, or a system, supports organizational functions or processes.

• System: Turns data into information and includes:– Hardware and system software

– Documentation and training materials

– Job roles associated with the system

– Controls to prevent theft or fraud

– The people who use the software to perform their jobs

• Figure 1-2 illustrates all the components of a system.

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Software Engineering Process• A process used to create an information system• Consists of:

– Methodologies• A sequence of step-by-step approaches that help develop the

information system Most methodologies incorporate severaldevelopment techniques, such as direct observations and interviewswith users of the current system.

– Techniques• Processes that the analyst follows to ensure thorough, complete,

and comprehensive analysis and design planning and managing the activities in a systems development project designing the reports, such as invoices

– Tools• Computer programs that aid in applying techniques such as

computer-aided software engineering (CASE) tools, that make it easy to use specific techniques.

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System• A system is an interrelated set of business procedures used

within one business unit working together for a purpose.• A system has nine characteristics.• A system exists within an environment.• A boundary separates a system from its environment.

Characteristics of a System• Components• Interrelated Components• Boundary• Purpose• Environment• Interfaces• Constraints• Input• Output

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Important System Concepts• Decomposition

– The process of breaking down a system into smaller components

– Allows the systems analyst to:• Break a system into small, manageable and

understandable subsystems

• Focus on one area at a time, without interference from other areas

• Concentrate on component pertinent to one group of users without confusing users with unnecessary details

• Build different components at independent times and have the help of different analysts

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Important System Concepts

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Important System Concepts (continued)

• Modularity– Process of dividing a system into modules of

a relatively uniform size

– Modules simplify system design

• Coupling– Subsystems that are dependent upon each

other are coupled

• Cohesion– Extent to which a subsystem performs a

single function

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A Modern Approach to Systems Analysis and Design

• Systems Integration– Allows hardware and software from different vendors to

work together

– Enables procedural language systems to work withvisual programming systems

– Visual programming environment uses client/servermodel. Internet is also organized in a client/serverformat

– Enterprise-wide system from companies such as SAP(Systems, Applications, and Products in Data Processing)Oracle , JDE

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A Modern Approach to Systems Analysis and Design

• Systems Integration

– Developers assemble systems by choosing andimplementing specific modules.

– an enterprise-wide system may handle all humanresources management, payroll, benefits, and retirementfunctions within a single, integrated system.

– organizations develop systems in-house anymore.

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A Modern Approach to Systems Analysis and Design

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Your Role in Systems Development• Primary Responsibility rather than other. key to the

systems development process

• Position is found in small and large companies.

• to study the problems and needs of an organizationin order to determine how people, methods, andinformation technology can best be combined tobring about improvements in the organization.

• Help system users and managers define theirrequirements for new or enhanced informationsystems

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Skills of system analyst • Analytical skills: able to understand the organization

and its functions, to identify opportunities andproblems, and to analyze and solve problems.

• Technical skills: able understand the power and thelimitations of information technology. Programminglanguages, Operation systems , Hardware platforms,

• Management skills: able to manage teams, projects,risks and change.

• Interpersonal skills: able to work with other analystand programmers , end users and professionals,effective writing and oral communications, leadingmeetings, conferences, interviews, good listener.

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Your Role in Systems Development

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Outsourcing

• Practice of another organization developing and/or running a computer application for your organization

• Many types of working arrangements

• Should be considered as one possible alternative to developing a system

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Sources of SoftwareWhat is done when a problem raised ?

• When developing information systems to deal with such problems, an organization and its systems analysts have several options:

• Go to Information Technology Services Firms, HP

• Packaged Software Providers on shelf SW (Buy)

• Implement Wide Enterprise Solutions Software SAP

• Open-Source Software

• Use In-House stuff for developing solution

• Out sourcing system development and operations

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Types of Information Systemsand Systems Development

• Transaction Processing Systems (TPS)– Automate handling of data about business activities

(transactions)

• Management Information Systems (MIS)– Converts raw data from transaction processing system into

meaningful form

• Decision Support Systems (DSS)– Designed to help decision makers

– Provides interactive environment for decision making

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Sources of Software Components

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SDLC• System Development Methodology SDM

– Any Organizations use a standard set of steps, called aSDM, to develop and support their information systems.Like many processes, the development of informationsystems often follows a life cycle.

– For example, a commercial product, such as a Nikesneaker or a Honda car, follows a life cycle: It is created,tested, and introduced to the market. Its sales increase,peak, and decline. Finally, the product is removed fromthe market and is replaced by something else.

– Phases are not necessarily sequential.

– Each phase has a specific outcome and deliverable.

– Individual companies use customized life cycle30

Developing Information Systems and the SDLC

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SDLC- Systems Planning and Selection– Main Activities

• Identification of need for enhancing thecurrent system or for new system ( written planeof IS dept.), schedule for developing new system.

• A feasibility study is conducted before thesecond phase of the SDLC to determine theeconomic and organizational impact of thesystem.

• Investigation and determination of scope

• The final presentation to the organization’smanagement of the plan for proceeding with thesubsequent project phases is usually made bythe project leader and other team members.

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• The analyst studies the organization’s current proceduresand information systems used to perform tasks such asgeneral ledger GL, shipping, order entry, machine scheduling,and payroll.

• Determine requirements : what the users want from aproposed system a careful study of any current systems,manual and computerized, that might be replaced or enhancedas part of this project.

• Generate alternative initial designs to match therequirements

• Compare alternatives and Recommend best alternative

• The output of the analysis phase is a description of thealternative solution recommended by the analysis team.

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SDLC- Systems Planning and Selection

• The recommended alternative solution is presented intological and then physical system specifications.

• Input screens, output screen and reports.

• Databases, and computer processes.

• Environment Independent ( HW and SW)

• Logical Design• Concentrates on business aspects of the system

• Physical Design• Technical specifications.• The analyst team decides which programming languages , DBMS , HW ,

Operating system , Network environment.

• The final product of the design phase is the physicalsystem specifications presented in a form, such as adiagram or written report, ready to be turned over toprogrammers and other system builders for construction.

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SDLC- System Design

SDLC – Implementation and operation

• System Implementation and Operation– Implementation

• Coding: Write Programs the make up the system.

• Testing : Testing the program to find errors if exist.

• Installation: Application is installed on the New HW.

• User is introduced to the system an trained on it

• Documentation

– Users sometimes find problems with how it worksand often think of improvements.

– The amount of time and effort devoted to systemenhancements during operation depends a great dealon the performance of the previous phases of SDLC.

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Products of the SDLC

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Alternative Approaches to Development

• Prototyping– Building a scaled-down working version of the system

– The analyst works with users to determine the basicrequirements for the system.

– The analyst then quickly builds a prototype.

– the users check it and tell the analyst what they like and do notlike about it.

– The analyst uses this feedback to improve the prototype andtakes the new version back to the users.

– This iterative process continues until the users are relativelysatisfied with what they have seen.

– Advantages:• Users are involved in design

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Alternative Approaches to Development

• Prototyping

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Approaches to Development (continued)• Computer-Assisted Software Engineering (CASE) Tools

– Automated software tools used by systems analysts to develop information systems

– Can be used throughout SDLC

– Product and tool integration is provided through a repository.

– General types of CASE tools

• Diagramming tools

• Computer display and report generators

• Analysis tools

• Repository

• Documentation generators

• Code generators39

Selecting Off-the-Shelf Software• Cost: comparing the cost of developing the same system in-house

with the cost of purchasing or licensing the software package

• Functionality: the tasks that the software can perform and themandatory, essential, and desired system features

• Vendor support: whether or how much support the vendor canprovide and at what cost.

• Viability of vendor: can the software adapt to changes in systemssoftware and hardware

• Flexibility: how easy it is to customize the software

• Documentation: is the user’s manual and technicaldocumentation understandable and up-to-date

• Response time: how long it takes the software package torespond to the user’s requests in an interactive session

• Ease of installation: a measure of the difficulty of loading thesoftware and making it operational

• compatibility with currently used application

software and HW. hardware and system software

Validating Purchased Software Information

• Use a variety of information sources:

– Collect information from vendor

– Software documentation

– Technical marketing literature

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Questions1. What is the information systems analysis and design?

2. What is meant by the system, list the main characteristics ofthe system?

3. What is meant by methodology , Tools , Techniques?

4. What is decomposition? Coupling? Cohesion?

5. In what way are organizations systems?

6. Describe the major Types of Information systems?

7. What is meant by outsourcing? And what are the mainsources of software?

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Questions8. What is the main role of the analyst? And what are the skills

that must be achieved in the system analysis?

9. List and explain the different phases in the systemsdevelopment life cycle.

10. What is prototyping?

11. What are CASE tools? What is a CASE repository and how is itused?

12. How can you decide among various off-the shelf softwareoptions? What criteria should you use?

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