Chap1 Sdlc

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    THE SYSTEMSTHE SYSTEMS

    DEVELOPMENTDEVELOPMENTTOOLSTOOLS

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    OBJECTIVESOBJECTIVES

    In the end of this section, student should be able to:

    Differentiate common system development tools:

    (a) modelling

    (b) prototyping

    (c) CASE tools

    List and explain five phases of the SDLC:

    (a) planning

    (b) analysis

    (c) design

    (d) implementation

    (e) support

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    System

    Development

    Tools

    System

    Development

    Tools

    Prototyping

    Modelling

    CASE tools

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    (a) Modelling(a) Modelling

    Models are needed in order to help the

    analyst to understand the functionality ofthe system and models are used to

    communicate with customers.

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    Types of modelling:

    i) Data processing model data is

    processed at different stages

    ii) Composition model entities arecomposed of other entities

    (a) Modelling (cont.)(a) Modelling (cont.)

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    iii)Architectural model showing principal

    sub-system

    iv) Classification model entities have

    common characteristics

    v) Stimulus/response model systems

    reaction to events

    (a) Modelling (cont.)(a) Modelling (cont.)

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    (b) Prototyping(b) Prototyping

    Prototyping is the process of building amodel of a system.

    In terms of an information system,

    prototypes are employed to help systemdesigners build an information systemthat intuitive and easy to manipulate forend users.

    Prototyping is an iterative process that ispart of the analysis phase of the SDLC

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    Advantages of Prototyping:(a) Reduces development time.

    (b) Reduces development costs.

    (c) Requires user involvement.(d) Developers receive

    quantifiable user feedback.

    (e) Facilitates system implementation

    since users know what to expect.

    (f) Results in higher user satisfaction.

    (g) Exposes developers to potential

    future system enhancements.

    (b) Prototyping (cont.)(b) Prototyping (cont.)

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    Disadvantages of prototyping:

    (a) Can lead to insufficient analysis.

    (b) Users expect the performance of the

    ultimate system to be the same as the

    prototype.

    (c) Developers can become too attached

    to their prototypes.(d) Can cause systems to be left

    unfinished and / or implemented

    before they are ready.

    (b) Prototyping (cont.)(b) Prototyping (cont.)

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    (e) Sometimes leads to incomplete

    documentation.

    (f) If sophisticated software prototypes(4th GL or CASE Tools) are employed,

    the time saving benefit of prototyping

    can be lost.

    (b) Prototyping (cont.)(b) Prototyping (cont.)

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    (c) CASE tools(c) CASE tools

    CASE is the abbreviation of Computer-

    Aided Software Engineering.

    CASE tools are productivity tools for

    systems analysts that have been createdexplicitly to improve their routine work

    through the use of automated support

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    Reasons for using CASE tools

    - Increasing Analyst Productivity

    - Improving Analyst-User

    Communication

    - Integrating Life Cycle Activities

    - Accurately Assessing Maintenance

    Changes

    (c) CASE tools (cont.)(c) CASE tools (cont.)

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    Case Tool Classifications:

    1.Upper CASE tools perform analysis and

    design

    2. Lower CASE tools generate programs

    from CASE design

    3. Integrated CASE tools perform both

    upper and lower CASE functions

    (c) CASE tools (cont.)(c) CASE tools (cont.)

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    Upper CASE Tools

    - Create and modify the system design

    - Help in modeling organizational

    requirements and defining system

    boundaries

    - Can also support prototyping of screen

    and report designs

    (c) CASE tools (cont.)(c) CASE tools (cont.)

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    Lower CASE tools

    - Lower CASE tools generate computersource code from the CASE design

    - Source code is usually generated in

    several languages

    -Traditional versus CASE systems

    development life cycle

    (c) CASE tools (cont.)(c) CASE tools (cont.)

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    Analysis DesignProgram

    Design &

    Coding

    Program

    Testing

    Installation

    Requirements

    ProgramSpecs

    ProgramSourceCode

    CompletedSystem

    DesignQuestions

    ProgramSpecificationQuestions

    Program Bugsand Errors

    InstallationBugs

    Design Upper CASEToolset

    Lower CASEToolset(Code

    Generation)

    Installation

    Requirements

    CASEDesignEntities

    CASERepository

    Error-FreeComputerSystem

    DesignQuestions

    Design Flaws &Inconsistencies

    CASE Systems Development Life Cycle

    Traditional Systems Development Life Cycle

    Analysis

    Traditional vs CASE SDLCTraditional vs CASE SDLC

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    System Development Tools

    Differentiation

    System Development Tools

    Differentiation

    MODELLING PROTOTYPING CASE tools

    Abstract

    descriptions ofsystem

    Process of building

    a model of asystem

    Software systems

    which are intendedto provide

    automated support

    for softwareprocess activities.

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    THE SYSTEMSTHE SYSTEMS

    DEVELOPMENTDEVELOPMENT

    LIFE CYCLELIFE CYCLE

    (SDLC)(SDLC)

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    The systems development life cycle is a

    phased approach to solving businessproblems

    Developed through the use of a specific

    cycle of analyst and user activities Each phase has unique user activities

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    The systems development life cycle

    (SDLC) is a general term used to describethe method and process of developing a

    new information system

    W

    ithout the structure and organizationprovided by SDLC approach projects are

    at risk for missed deadline, low quality etc.

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    SDLC provides

    StructureMethods

    Controls

    ChecklistNeeded for successful development

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    Phases of the SDLCPhases of the SDLC

    The SDLC is composed of five fundamental

    phases (major phases):

    Planning

    Analysis

    Design

    Implementation

    Support

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    Each of the phases include a set

    of steps, which rely on

    techniques that produce specific

    document files that provide

    understanding about the project.

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    Phase I : PlanningPhase I : Planning

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    This phase is the fundamental process of

    understanding why an information system

    should be built.

    The Planning phase will also determine

    how the project team will go about building

    the information system.

    The Planning phase is composed of two

    planning steps.

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    Two Planning StepsTwo Planning Steps

    1. During project initiation, the

    systems business value to the

    organization is identified (How will

    it lower costs or increaserevenues?)

    2. During project management, the

    project manager creates a work

    plan, staffs the project, and putstechniques in place to help the

    project team control and direct the

    project through the entire SDLC.

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    Phase II : AnalysisPhase II : Analysis

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    The analysis phase answers the questions of who

    will use the system, what the system will do, and

    where and when it will be used.

    During this phase the project team investigates

    any current systems, identifies improvement

    opportunities, and develops a concept for thenew system.

    This phase has three analysis steps.

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    Phase I : Planning

    Three Analysis StepsThree Analysis Steps

    1. Analysis strategy: This is developed to guidethe projects teams efforts. This includes an

    analysis of the current system.2. Requirements gathering: The analysis of this

    information leads to the development of aconcept for a new system. This concept is

    used to build a set of analysis models.3. System proposal: The proposal is presentedto the project sponsor and other keyindividuals who decide whether the projectshould continue to move forward.

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    The system proposal is the initial deliverable that

    describes what business requirements the newsystem should meet.

    The deliverable from this phase is both an

    analysis and a high-level initial design for thenew system.

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    Phase III : DesignPhase III : Design

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    Is the process of defining thearchitecture, components,

    modules, interfaces and data for

    a system to satisfy specifiedrequirements

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    Five Design StepsFive Design Steps

    1. Design Strategy: This clarifies

    whether the system will be developed

    by the company or outside the

    company.

    2. Architecture Design: This describes

    the hardware, software, and network

    infrastructure that will be used.

    3. Interface Design: Define the software

    that will be used and how the system

    will look alike.

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    4. Database and File Specifications:

    These documents define what and

    where the data will be stored.

    5. Program Design: Defines whatprograms need to be written and

    what they will do.

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    Phase IV: ImplementationPhase IV: Implementation

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    Processes and DeliverablesProcesses and Deliverables

    During this phase, the system is

    either developed or purchased (in

    the case of packaged software).

    This phase is usually the longest

    and most expensive part of the

    process.

    The phase has three steps.

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    1. System Construction: The system

    is built and tested to make sure it

    performs as designed.

    2. Installation: Prepare to support the

    installed system.

    3. Support Plan: Includes a post-

    implementation review.

    Three Implementation StepsThree Implementation Steps

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    Phase V: SupportPhase V: Support

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    Is needed by the customer to

    make sure that problems will besolved.

    The developer should be giving

    training and support accordingto their agreement with the

    customer.

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    Process Product

    Planning

    Analysis

    Design

    Implementation

    Project Plan

    System Proposal

    SystemSpecification

    New System andMaintenance Plan

    SummarySummary