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Chapter 17 Current Trends in System Development

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Title: Chapter 17 Current Trends in System Development


1
Chapter 17 Current Trends in System Development
  • Systems Analysis and Design in a Changing World,
    5th Edition

2
Learning Objectives
  • Explain the foundations for the adaptive
    development methodologies
  • List and describe the features of the Unified
    Process system development methodology
  • List and describe the features of Agile Modeling
  • Compare and contrast the features of Extreme
    Programming and Scrum development
  • Explain the importance of Model-Driven
    Architecture on enterprise-level development
  • Describe frameworks and components, the process
    by which they are developed, and their impact on
    system development

3
Overview
  • The IS discipline is dynamic and always changing
  • More complex system requirements have
    necessitated a whole new set of tools
  • The Unified Process (UP)?
  • Radical, adaptive approaches, including Agile
    Development, Extreme Programming, and Scrum
  • Model-Driven Architecture for enterprise-level
    systems
  • Object frameworks and components to increase
    productivity and quality

4
Software Principles and Practices
  • Ubiquitous computing is the current trend in our
    society
  • Using computer technology in every aspect of our
    lives
  • The effort to develop current solutions is
    demanding
  • Current trends in modeling and development
    processes use five important principles
  • Abstraction
  • Process of extracting core principles from a set
    of facts or statement
  • Example Metamodels describe the characteristics
    of another model
  • Models and modeling
  • An abstraction of something in the real world,
    representing a particular set of properties

5
Software Principles and Practices (contd)?
  • Patterns
  • Standard solutions to a given problem or
    templates that can be applied to a problem
  • Reuse
  • Building standard solutions and components that
    can be used over and over again
  • Methodologies
  • A processincluding the rules, guidelines, and
    techniquesthat defines how systems are built

6
Adaptive Approaches to Development
  • Opposite end of spectrum from predictive
    approaches (recall Chapter 2)?
  • Allow for uncertainty
  • Use empirical controls, not predictive controls
  • Describe processes that are variable and
    unpredictable
  • Monitor progress and make corrections on the fly

7
Adaptive Approaches to Development
Characteristics
  • Less emphasis on up-front analysis, design, and
    documentation
  • More focus on incremental development
  • More user involvement in project teams
  • Reduced detailed planning
  • Used for near-term work phases only
  • Tightly control schedules by fitting work into
    discrete time boxes
  • More use of small work teams that are
    self-organizing

8
The Unified Process (UP)?
  • Object-oriented system development methodology
    (system development process)?
  • Offered by Rational/IBM, UP developed by Booch,
    Rumbaugh, and Jacobson
  • UP should be tailored to organizational and
    project needs
  • Highly iterative life cycle
  • Project will be use-case driven and modeled using
    UML

9
The Unified Process Life Cycle
  • UP life cycle
  • Includes four phases which consist of iterations
  • Iterations are mini-projects
  • Inception develop and refine system vision
  • Elaboration define requirements and design and
    implement core architecture
  • Construction continue design and implementation
    of routine, less risky parts
  • Transition move the system into operational
    mode

10
The Unified Process Life Cycle
Figure 17-1
11
UP Phases and Objectives
Figure 17-2
12
The UP Disciplines
  • UP defines disciplines used within each phase
  • Discipline set of functionally related
    development activities
  • Each iteration includes activities from all
    disciplines
  • Activities in each discipline produce artifacts
    models, documents, source code, and executables
  • Learning CIS/MIS means learning techniques from
    these disciplines
  • Six main UP development disciplines
  • Business modeling, requirements, design,
    implementation, testing, and deployment
  • Three additional support disciplines
  • Project management, configuration and change
    management, and environment

13
The UP Disciplines (contd)?
  • Six main UP development disciplines
  • Business modeling, requirements, design,
    implementation, testing, and deployment
  • Three additional support disciplines
  • Project management, configuration and change
    management, and environment

14
UP Disciplines Used in Varying Amounts in Each
Iteration
Figure 17-3
15
UP Life Cycle Model Showing Phases, Iterations,
and Disciplines
Figure 17-4
16
The Agile Development Philosophy and Modeling
  • Agile Development Principles
  • A philosophy and set of guidelines for developing
    software in an unknown, rapidly changing
    environment
  • Requires agility being able to change direction
    rapidly, even in the middle of a project
  • Agile Modeling Principles
  • A philosophy about how to build models, some of
    which are formal and detailed and others are
    sketchy and minimal

17
Adaptive Methodologies Using Agile Modeling
Figure 17-5
18
The Agile Development Philosophy and Values
  • Responding to change over following a plan
  • An agile project is chaordic both chaotic and
    ordered
  • Individuals and interactions over processes and
    tools
  • Working software over comprehensive documentation
  • Customer collaboration over contract negotiation

19
Agile Modeling Principles
  • AM is about doing the right kind of modeling at
    the right level of detail for the right purposes
  • Use models as a means to an end instead of
    building models as end deliverables
  • Does not dictate which models to build or how
    formal to make those models
  • Has basic principles to express the attitude that
    developers should have as they develop software

20
Agile Modeling Principles
Figure 17-6
21
Agile Modeling Practices
Figure 17-7
22
Extreme Programming (XP)?
  • An adaptive, agile development methodology
    created in the mid-1990s
  • Takes proven industry best practices and focuses
    on them intensely
  • Combines those best practices (in their intense
    form) in a new way to produce a result that is
    greater than the sum of the parts

23
XP Core Values
  • Communication
  • In open, frequent verbal discussions
  • Simplicity
  • In designing and implementing solutions
  • Feedback
  • On functionality, requirements, designs, and code
  • Courage
  • In facing choices such as throwing away bad code
    or standing up to a too-tight schedule

24
Some XP Practices
  • Planning
  • Users develop a set of stories to describe what
    the system needs to do
  • Testing
  • Tests are written before solutions are
    implemented
  • Pair programming
  • Two programmers work together on designing,
    coding, and testing
  • Simple designs
  • KISS and design continuously

25
Some XP Practices (contd)?
  • Refactoring
  • Improving code without changing what it does
  • Owning the code collectively
  • Anyone can modify any piece of code
  • Continuous integration
  • Small pieces of code are integrated into the
    system daily or more often
  • System metaphor
  • Guides members towards a vision of the system

26
Some XP Practices (contd)?
  • On-site customer
  • Intensive user/customer interaction required
  • Small releases
  • Produce small and frequent releases to
    user/customer
  • Forty-hour work week
  • Project should be managed to avoid burnout
  • Coding standards
  • Follow coding standards to ensure flexibility

27
XP Core Values and Practices
Figure 17-8
28
XP Project Activities
  • System-level activities
  • Occur once during each development project
  • Involve creating user stories to planning
    releases
  • Release-level activities
  • Cycle multiple times once for each release
  • Are developed and tested in a period of no more
    than a few weeks or months
  • Iteration-level activities
  • Code and test a specific functional subset in a
    few days or weeks

29
XP Development Approach
Figure 17-9
30
Scrum
  • A quick, adaptive, and self-organizing
    development methodology
  • Named after rugbys system for getting an
    out-of-play ball into play
  • Responds to a current situation as rapidly and
    positively as possible
  • A truly empirical process control approach to
    developing software

31
Scrum Philosophy
  • Responsive to a highly changing, dynamic
    environment
  • Focuses primarily on the team level
  • Team exerts total control over its own
    organization and work processes
  • Uses a product backlog as the basic control
    mechanism
  • Prioritized list of user requirements used to
    choose work to be done during a Scrum project

32
Scrum Organization
  • Product owner
  • The client stakeholder for whom a system is being
    built
  • Maintains the product backlog list
  • Scrum master
  • Person in charge of a Scrum project
  • Scrum team or teams
  • Small group of developers
  • Set their own goals and distribute work among
    themselves

33
Scrum Practices
  • Sprint
  • The basic work process in Scrum
  • A time-controlled mini-project
  • Firm 30-day time box with a specific goal or
    deliverable
  • Parts of a sprint
  • Begins with a one-day planning session
  • A short daily Scrum meeting to report progress
  • Ends with a final half-day review

34
Scrum Software Development Process
Figure 17-10
35
Project Management and Adaptive Methodologies
  • Project time management
  • Smaller scope and focused on each iteration
  • Realistic work schedules
  • Project scope management
  • Users and clients are responsible for the scope
  • Scope control consists of controlling the number
    of iterations
  • Project cost management
  • More difficult to predict because of unknowns
  • Project communication management
  • Critical because of open verbal communication and
    collaborative work

36
Project Management and Adaptive Methodologies
(contd)?
  • Project quality management
  • Continual testing and refactoring must be
    scheduled
  • Project risk management
  • High-risk aspects addressed in early iterations
  • Project human resource management
  • Teams organize themselves
  • Project procurement management
  • Integrating purchased elements into the overall
    project
  • Verifying quality of components
  • Satisfying contractual commitments

37
Model-Driven Architecture
  • Model-Driven Architecture (MDA) is an OMG (Object
    Management Group) initiative
  • Built on the principles of abstraction, modeling,
    reuse, and patterns
  • Provides companies with a framework to identify
    and classify all system development work being
    done in an enterprise
  • MDA extracts current systems features and
    information and combines them into a platform
    independent model (PIM)?

38
Model-Driven Architecture (contd)?
  • Platform-independent model (PIM)?
  • Describes system characteristics that are not
    specific to any deployment diagram
  • Uses UML
  • Platform-specific model (PSM)?
  • Describes system characteristics that include
    deployment platform requirements
  • A set of standard transformations by the OMG move
    a PSM to a PIM

39
Software Development and MDA
Figure 17-11
40
Metamodels and Transitions between PIM, PSM, and
Code
Figure 17-12
41
Partial Metamodel of UML Class Diagram
Figure 17-13
42
Object Frameworks
  • A set of classes that are designed to be reused
    in a variety of programs
  • The classes within an object framework are called
    foundation classes
  • Can be organized into one or more inheritance
    hierarchies
  • Application-specific classes can be derived from
    existing foundation classes

43
Object Framework Types
  • User-interface classes
  • Commonly used objects within a GUI
  • Generic data structure classes
  • Linked lists, binary trees, and so on, and
    related processing operations
  • Relational database interface classes
  • Classes to create and perform operations on
    tables
  • Classes specific to an application area
  • For use in a specific industry or application type

44
Impact on Design and Implementation
  • Frameworks must be chosen early in the project
  • Systems design must conform to specific
    assumptions about application program structure
    and operation that the framework imposes
  • Design and development personnel must be trained
    to use a framework effectively
  • Multiple frameworks might be required,
    necessitating early compatibility and integration
    testing

45
Components
  • Software modules that are fully assembled and
    ready to use
  • Reusable packages of executable code
  • Have well-defined interfaces to connect them to
    clients or other components
  • Public interfaces and encapsulated implementation
  • Standardized and interchangeable
  • Updating a single component does not require
    relinking, recompiling, and redistributing an
    entire application

46
Component Standards and Infrastructure
  • Interoperability of components requires standards
    to be developed and readily available
  • Components might also require standard support
    infrastructure
  • Software components have more flexibility when
    they can rely on standard infrastructure services
    to find other components
  • Networking standards are required for components
    in different locations

47
CORBA and COM
  • CORBA (Common Object Request Broker Architecture)
    is a standard for software component connection
    and interaction developed by the OMG
  • An object request broker (ORB) provides component
    directory and communication services
  • The Internet Inter-ORB Protocol (IIOP) is used to
    communicate among objects and ORBs
  • Component Object Model Plus (COM) is a standard
    for software component connection and interaction
    developed by Microsoft

48
Enterprise JavaBeans
  • Part of the Java programming languages extensive
    object framework (JDK)?
  • A JavaBean can execute on a server and
    communicate with clients and other components
    using CORBA
  • A JavaBean implements the required component
    methods and follows the required naming
    conventions of the JavaBean standard
  • Platform independent

49
Components and the Development Life Cycle
  • Component purchase and reuse is a viable approach
    to speeding completion of a system
  • Purchased components can form all or part of a
    newly developed or re-implemented system
  • Components can be designed in-house and deployed
    in a newly developed or re-implemented system

50
Using Purchased Components Implications
  • Standards and support software of purchased
    components must become part of the technical
    requirements definition
  • A components technical support requirements
    restrict the options considered during software
    architectural design

51
Monitoring System Performance
  • Examine component-based designs to estimate
    network traffic patterns and demands on computer
    hardware
  • Examine existing server capacity and network
    infrastructure to determine their ability to
    accommodate communication among components
  • Upgrade network and server capacity prior to
    development and testing
  • Test system performance during development and
    make any necessary adjustments
  • Continuously monitor system performance after
    deployment to detect emerging problems
  • Redeploy components, upgrade server capacity, and
    upgrade network capacity to reflect changing
    conditions

52
Services
  • New method of software reuse enabled by
    Internetexternal services identified and used
    for applications
  • Called Web services and service-oriented
    architecture (SOA)?
  • Microsoft .NET is service standard based on SOAP
  • Java 2 Web Services (J2WS) is service standard
    for services in Java

53
Component Communication Using SOAP
Figure 17-14
54
Summary
  • Adaptive development methodologies
  • Unified Process (UP)?
  • Agile Modeling and Agile Development
  • Flexibility in an unpredictable business world
  • Extreme Programming (XP)?
  • Tests are written first programmers work in
    pairs
  • Scrum
  • Defines a specific goal that can be completed
    within four weeks
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