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Modern Systems Analysis and Design

Chapter 1 The Systems Development Environment 1.1 Copyright 2002 Prentice-Hall, Inc.

Introduction Information Systems Analysis and Design – Complex process whereby computerbased information systems are developed and maintained

Application Software – Result of systems analysis and design – Designed to support specific organizational functions or processes 1.5

Introduction Software engineering processes have been developed to assist in system analysis and design – Methodologies Comprehensive, multi-step approaches to systems development

– Techniques Processes that are followed to ensure that work is well thought-out, complete and comprehensible to others on the project team

– Tools Computer programs to assist in application of techniques to the analysis and design process 1.6

Introduction Information Systems Analysis and Design – A method used by companies to create and maintain systems that perform basic business functions – Main goal is to improve employee efficiency by applying software solutions to key business tasks – A structured approach must be used in order to ensure success

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Introduction 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

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Key Components of an Information System Data – Raw facts that describe people, objects and events in an organization

Data Flows – Groups of data that move and flow through the system – Include description of sources and destination for each data flow

Processing Logic – Describe steps that transform data and events that trigger the steps

Data vs. Information Data – Raw facts

Information – Derived from data – Suitable for human interpretation

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Approaches to Systems Development: I Separating Data and Processes that Handle Data – Process oriented approach Focus is on output and processing logic Based upon what the system was supposed to do, liking billing and inventory control Disadvantage: data files are tied to specific applications

– Data-Oriented Approach Depicts ideal organization of data, independent of where and how data are used 1.9

Approaches to Systems Development Data-Oriented Approach – Data model describes the kinds of data and business relationships among the data – Business rules depict how organization captures and processes the data

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Approaches to Systems Development: II Separating Databases and Applications: – Database Shared collection of logically related data Centrally managed, standardized and consistent Sole source of data for multiple applications

– Application Independence: Separation of data and definition of data from applications Databases are designed around subjects

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Organizational Responsibilities in Systems Development Skills of a Successful Systems Analyst – Analytical Understanding of organizations Problem solving skills System thinking – Ability to see organizations and information systems as systems

– Technical Understanding of potential and limitations of technology

– Management Ability to manage projects, resources, risk and change

– Interpersonal 1.12

Effective written and oral communication skills

Types of Information Systems and Systems Development Transaction Processing Systems (TPS) – Automate handling of data about business activities

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

Decision Support Systems (DSS) – Interactive environment for decision making – Contain a database, model base and user interface

Expert Systems (ES) – Codify and manipulate knowledge rather than information – Interactive: ask users a sequence of questions dependent on prior answers, which lead to a conclusion or recommendation 1.13

Systems Development Life Cycle A common system development methodology – Standard process followed in an organization – Consists of: Analysis Design Implementation Maintenance 1.14

Systems Development Life Cycle Series of steps used to manage the phases of development for an information system Consists of six phases: – – – – – – 1.15

Project Identification and Selection Project Initiation and Planning Analysis Design Implementation Maintenance

Phases of the SDLC Project Identification and Selection

Project Initiation and Planning Analysis Logical Design

Physical Design Implementation Maintenance

Systems planning and selection

Systems Analysis

Systems Design

Systems Implementati on and Operation

Systems Development Life Cycle – Phases are not necessarily sequential Return to an earlier phase In parrelle Interactive Circular

– Each phase has a specific outcome and deliverable – Individual companies use customized life cycles 1.17

Phases of SDLC Project Identification and Selection – Two Main Activities Identification of need Prioritization and translation of need into a development schedule

– Outcome: a determination of which project should be undertaken

Project Initiation and Planning – Two Activities Formal preliminary investigation of the problem at hand Presentation of reasons why system should or should not be developed by the organization

– Outcome: a specified baseline project plan 1.18

Phases of SDLC Analysis – Study of current procedures and information systems Determine requirements – Study current system – Structure requirements and eliminate redundancies

Generate alternative designs Compare alternatives Recommend best alternative 1.19

Phases of SDLC (Cont.) Design

– Logical Design Independent of any hardware or software platform

– Physical Design

Technical specifications

Implementation – – – –

Programming and testing Hardware and software installation User Training Documentation

Maintenance 1.20

– System changed to reflect changing conditions – System obsolescence

Approaches to Development Prototyping – Design and building a scaled-down working version of the system – Advantages: Users are involved in design Captures requirements in concrete form

– A form of Rapid Application Development (RAD) Utilizes prototyping to delay producing system design until after user requirements are clear 1.21

Approaches to Development Joint Application Design (JAD) – Users, Managers and Analysts work together for several days – System requirements are reviewed – Structured meetings

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Improving IS Development Productivity Computer-aided software engineering (CASE) tools – Facilitate creation of a central repository of information for system descriptions and specifications – Automating routing tasks

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Summary Information systems analysis and design – Process of developing and maintaining an information system

Modern approach to systems analysis – Process-Oriented – Data-Oriented

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Summary Four types of information systems – Transaction Processing (TPS) – Management Information Systems (MIS) – Decision Support (DSS) – Expert Systems (ES)

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Summary Systems Development Life Cycle (SDLC) – Project Identification and Selection – Project Initiation and Planning – Analysis – Design – Implementation – Maintenance 1.26

Summary Alternatives to Systems Development Life Cycle – Prototyping – Rapid Application Development (RAD) – Joint Application Design (JAD)

Computer-aided software engineering (CASE) tools 1.27