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					System Analysis and Design Fundamentals




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Outline

    Introduction
    system definition, characteristics, concepts
    Data, Information
     Type of Information system
    SDLC




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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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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
     Systems Development Life Cycle




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Information Systems Analysis and Design




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Systems Analysis and Design: Core Concepts

     Major goal: to improve organizational systems by
      developing or acquiring software and training
      employees in its use
     Application software, or a system, supports
      organizational functions or processes




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Systems Analysis and Design: Core Concepts

       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



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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
        – Techniques
          » Processes that the analyst follows to ensure thorough,
            complete and comprehensive analysis and design
        – Tools
          » Computer programs that aid in applying techniques


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System Definition

     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



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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 subsystems
        Focus on one area at a time
        Concentrate on component pertinent to one group of
         users
        Build different components at independent times

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Important System Concepts
   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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Important System Concepts

     Logical System Description
       – Portrays the purpose and function of the system
       – Does not tie the description to a specific
         physical implementation
     Physical System Description
       – Focuses on how the system will be materially
         constructed



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System Thinking

      Benefits
       – Identification of a system leads to abstraction
       – From abstraction you can think about essential
         characteristics of specific system
       – Abstraction allows analyst to gain insights into
         specific system, to question assumptions,
         provide documentation and manipulate the
         system without disrupting the real situation


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System Thinking

      Applying Systems Thinking to Information Systems
        – Information systems are subsystems in larger
          organizational systems
        – Data flow diagrams represent information systems as
          systems
           »   Inputs
           »   Outputs
           »   System boundaries
           »   Environment
           »   Subsystems
           »   Interrelationships


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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
           with visual programming systems
         – Visual programming environment uses
           client/server model



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Data and Processes

    Three key components of an information system
       Data
       Data Flows
       Processing Logic
   Data vs. Information
     – Data
       » Raw facts
    – Information
       » Derived from data
       » Organized in a manner that humans can
         understand                                 21
Data and Processes

     Data
      – Understanding the source and use of data is key
        to good system design
      – Various techniques are used to describe data
        and the relationship amongst data
     Data Flows
      – Groups of data that move and flow through the
        system


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Data and Processes

     Data Flows
       – Include description of sources and destination
         for each data flow
     Processing Logic
       – Describe steps that transform data and events
         that trigger the steps




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Approaches to Systems Development
    Process-Oriented Approach
      – Focus is on flow, use and transformation of
        data in an information system
      – Involves creating graphical representations
        such as data flow diagrams and charts
      – Data are tracked from sources, through
        intermediate steps and to final destinations
      – Natural structure of data is not specified
      – Data files are tied to specific applications


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Approaches to Systems Development

      Data-Oriented Approach
       – Depicts ideal organization of data, independent
         of where and how data are used
       – Data model describes kinds of data and
         business relationships among the data
       – Business rules depict how organization
         captures and processes the data



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Databases and Application Independence
    Database
      – Shared collection of logically related data
      – Organized to facilitate capture, storage and retrieval by
        multiple users
      – Centrally managed
      – Designed around subjects
         Customers
         Suppliers
    Application Independence
      – Separation of data and definition of data from
        applications


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Types of Information Systems
and Systems Development

 Transaction  Processing Systems (TPS)
   – Automate handling of data about
     business activities (transactions)
      » Information system that processes large
        amount of data for routine business
        transaction. Eg., payroll, inventory
      » Operate at operational level


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Types of Information Systems
and Systems Development

 Management    Information Systems (MIS)
   – Converts raw data from transaction
     processing system into meaningful form
      » Include transaction processing.
      » Have interaction between human and
        computers. Use people, hardware, software
      » Users of MIS share common database


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Types of Information Systems
and Systems Development

   Decision Support Systems (DSS)
    – Designed to help decision makers
    – Provides interactive environment for decision
      making
       » Similar to MIS as require database
       » Emphasize on the support of decision making
       » Tailored to special groups of people; not general as
         MIS



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Types of Information Systems
and Systems Development

       Expert Systems (ES)
         – Replicates decision-making process
         – Knowledge representation describes the way an
           expert would approach the problem
           » Unlike DSS, expert system decides the best
             solution for the problem while DSS leaves decision
             to a decision maker.
           » Require knowledge base.



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Types of Information Systems
and Systems Development
    Group decision support systems (GDSS) and
     computer –supported collaborative work systems
     (CSCW)
      – Use rooms equipped with configuration to
        permit group to interact with electronic
        support, special software, etc.
      – Intend to bring group together to solve a
        problem with various supports eg. Polling,
        questionnaires, brainstorming, scenario.
      – Software support is called “Groupware”

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Types of Information Systems
and Systems Development

       Office automation systems (OAS) and knowledge
        work systems (KWS)
        – OAS: Do not create new knowledge but
          analyze information to transform/manipulate
          before sharing.
        – KWS: support professional worker eg., doctors
          to create new knowledge and contribute it.



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Types of Information Systems
and Systems Development

       Executive support systems
         – Help users address unstructured decision
           problems which are not application specific.
         – Help executives to organize their interactions
           with external environment.




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Technology Integration




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Technology Integration

       Ecommerce applications and web system
         – Benefits
           » Increasing awareness of availability of service,
             product, industry, person, or group.
           » Possibility of 24 hrs access for users.
           » Standardizing the design of interface.
           » Creating the system that can extend globally rather
             than locally, reaching people in remote locations
             without worrying of time zone where they are
             located.


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Technology Integration

     Enterprise resource planning systems (ERP)
       – Integrate many information systems in an
         organization on different management level.
       – Eg. SAP , JD Edwards.
     System for wireless and handheld device
     Open source software




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Systems Development Life Cycle (SDLC)

    Series of steps used to manage the phases of
     development for an information system
    Consists of four phases:
      – Planning and Selection
      – Analysis
      – Design
      – Implementation and Operation
    Phases are not necessarily sequential
    Each phase has a specific outcome and deliverable
    Individual companies use customized life cycle
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4 Phases of the Systems Development Life
Cycle
    Systems Planning and Selection
      – Two Main Activities
          Identification of need
          Investigation and determination of scope
    Systems Analysis
      – Study of current procedures and information
        systems
          Determine requirements
          Generate alternative designs
          Compare alternatives
          Recommend best alternative
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Systems Development Life Cycle
   System Design
     – Logical Design
       » Concentrates on business aspects of the system
   – Physical Design
   – Technical specifications
 Implementation and Operation
   – Implementation
       » Hardware and software installation
       » Programming
       » User Training
       » Documentation
    – Operation
       » System changed to reflect changing conditions
       » System obsolescence                              42
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Detailed SDLC 7 phases




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Maintenance

      Impact of maintenance




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Maintenance

      Reason for maintenance
       – Software errors
       – Enhance capability of software: due to
          » User always requests additional features as he is
            familiar of systems.
          » Business changes over time,eg., new government ,
            new rules etc.
          » Hardware and software are changing at a rapid pace.



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Maintenance

      Amount of resources consumed for development
       and maintenance.




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Approaches to Development
    Prototyping
      – Building a scaled-down working version of the
        system
      – Advantages:
        » Users are involved in design
        » Captures requirements in concrete form
    Rapid Application Development (RAD)
     – Utilizes prototyping to delay producing system
       design until after user requirements are clear


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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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CASE tools

      CASE tools (Computer-Aided Software
       Engineering )
        – Upper CASE
           » Help analysts and designers
        – Lowe CASE
           » Help programmers and workers




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CASE tools

      Upper CASE tool
       – Help analysts to create/modify system design.
       – Contain CASE repository which stores
         collections of records, elements, diagrams,
         reports, etc.
       – Also help support modeling of organization,
         functional requirement, drawing boundary of
         project, visualize how projects related to other
         parts of organization, etc.


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CASE tools

      Lower CASE tools
        – Help programmers generate code: benefits are
          » System may be produced quickly.
          » Minimize human errors
          » Amount of time spent on maintenance is decreased.
            No need for modify, test, debug. Just modify the
            CASE tools and regenerate the code.
          » Code may be generated in many languages
          » Provide an cost-effective way to tailor product from
            third-party vendors to the need of organization since
            the cost is very high.
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CASE tools

      Traditional VS CASE SDLC




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Repository Concept




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CASE Repository

    Holds complete information needed to create,
     modify and evolve a software system from project
     initiation and planning to code generation and
     maintenance
    Two Primary Segments
      – Information Repository
      – Data Dictionary



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CASE Repository

      Information Repository
        – Combines information about an organization’s
          business information and its application
          portfolio
        – Provides automated tools to manage and
          control access to repository
        – Business Information
          » Data stored in corporate databases
       – Application Portfolio
          » Application programs used to manage business

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CASE Repository

      Data Dictionary
       – Computer software tool used to manage and
         control access to the information repository
       – Contains all data definitions for all
         organizational applications
       – Cross referencing
          » Enables one description of a data item to be stored
            and accessed by all individuals
          » Single definition for a data item is established and
            used

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CASE Repository

      Data Dictionary
       – Entries have a standard definition
          »   Element name and alias
          »   Textual description of the element
          »   List of related elements
          »   Element type and format
          »   Range of acceptable values
          »   Other information unique to the proper processing of this
              element




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CASE Repository

      CASE Repository and the SDLC
       – During project initiation and planning phase,
         all information related to the problem being
         solved is stored in the repository
          » Problem domain, project resources, history and
            organizational context
       – During analysis and design phases, store
         graphical diagrams and prototype forms and
         reports
       – Data stored in repository are used for basis to
         generate code and documentation
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CASE Repository

      Additional Advantages
       – Assistance with project management tasks
       – Aids in software reusability
          » The ability to design software modules in a manner so that
            they can be used again and again in different systems without
            significant modification




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CASE Documentation Generator Tools

    Enable the easy production of both technical and
     user documentation
    Allow creation of master templates used to verify
     that documentation conforms to all stages of
     SDLC




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CASE Code Generation Tools
 Enable  the automatic generation of program and
  database definition code directly from the design
  documents, diagrams, forms and reports stored in
  the repository




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Visual and Emerging Development Tools

      Object-Oriented Development Tools
       – Object
          » A chunk of program and data that is built to perform common
            functions within a system
          » Easily reused
          » Encapsulation
               Process of grouping data and instructions together

       – Development environment includes pre-defined
         objects and facilitates reuse of code


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Visual and Emerging Development Tools

      Visual Development Tools
       – Enable developers to quickly create user
         interfaces
       – Popular tools include:
          »   Microsoft Visual Studio
          »   Delphi
          »   Powerbuilder
          »   ColdFusion




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Reverse Engineering

       Software reverse engineering
         – Method for extending life time of old systems.




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Reverse Engineering

       Reverse engineering tool set produces
        – Data structures/elements, describing
          files/records stored by the system
        – Screen designs for online program
        – Report layouts for batch program
        – A structure chart showing hierarchy of modules
          in the program
        – Database design and relationship

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Reverse Engineering

       Advantages of reverse engineering
        – Reduced time required for maintenance. Free
          up time for new development
        – Documentation is produced.
        – Structured programs are created from
          nonstructured code.
        – Further maintenance is easier.
        – Analysis may be performed on the system to
          eliminate unused/obsolete code.

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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)
        – Etc.




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Summary
      Systems Development Life Cycle (SDLC)
        – Systems Planning and Selection
        – Systems Analysis
        – Systems Design
        – Systems Implementation
      Alternatives to Systems Development Life Cycle
        – Prototyping
        – Rapid Application Development (RAD)
        – Joint Application Design (JAD)
      CASE Tools
      Reverse Engineering
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posted:6/29/2011
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