Object-Oriented Development with Unified Process

Object-Oriented Development and the Unified Process

• The chapter introduces object-oriented analysis and design with the Unified Process.

Objectives

• Understand the traditional systems development life cycle (SDLC) and its phases.
• Learn when to use an adaptive SDLC approach instead of a predictive one.
• Explore how the adaptive Unified Process (UP) life cycle uses iterative and incremental development.
• Understand the differences between models, tools, techniques, and methodologies.
• See the Unified Process as a comprehensive system development methodology that combines proven best practices with the iterative UP life cycle.
• Learn the disciplines used in a UP development project.
• Identify the key features of the object-oriented approach.
• Learn how automated tools are used in system development.

Overview

• Traditional Systems Development Life Cycle
• Unified Process: An iterative, incremental, and adaptive approach to the life cycle.
• The UP has nine disciplines: six for the system development, and three for support.
• Object-Oriented concepts are reviewed
• Computer support tools like CASE are used
• Application of UP to the development project of RMO

The Systems Development Life Cycle

• SDLC is a process to build, deploy, and update information systems.
• The focus is on the initial development project.
• There are two chief variations of SDLC, predictive and adaptive.
• Predictive approach involves planning the entire project in advance.
• Adaptive approach involves planning that will leave room for contingencies.
• Pure approaches to SDLC are rare, and most projects have predictive and adaptive elements.
• The appropriate SDLC varies depending on the project.
• Predictive SDLC is best when requirements are well understood, and there is a low technical risk.
• Adaptive SDLC is best when requirements and needs are uncertain, and there is a high technical risk.

Traditional Predictive SDLC Approaches

• Project consists of activities or phases: planning, analysis, design, implementation, and support.
• Pure waterfall approach (predictive SDLC) is a project where phases are executed sequentially.
• In the waterfall approach, the project drops over into the next phase and there is no going back.
• Modified waterfall approach tempers the pure waterfall approach by recognizing phase overlap.
• The modified waterfall approach informs many current projects and company systems.
• The Waterfall model specifies sequential phases for software development.
• The waterfall model is document-driven where each step cannot begin until the previous step has been completed and documented.
• Design in the waterfall model is conceived as processes and data, not as objects.

Adaptive Approaches to the SDLC

• The spiral model is an early form of the adaptive SDLC.
• In the spiral model, activities radiate from the center starting point.
• Prototypes are artifacts of each phase.
• Iterative problem solving involves repeating activities.
• The are several approaches to structuring iterations:
  • Define and implement the key system functions.
  • Focus on one subsystem at a time.
  • Define by complexity or risk of certain components.
  • Complete parts incrementally.

The Unified Process Life Cycle

• UP life cycle includes 4 phases which consist of iterations.
• Iterations are considered "mini-projects".
• The 4 phases are:
  • Inception: develop and refine system vision
  • Elaboration: define requirements and core architecture
  • Construction: continue design and implementation
  • Transition: move the system into operational mode
• The spiral model is a risk-oriented lifecycle model that breaks a software project up into mini-projects.

Four Phases In The Unified Process

• Inception (Make the Business Case)
• Elaboration (Define the system architecture)
• Construction (Construct the system)
• Transition (Integrate the system with the using organization)

Methodologies, Models, Tools, and Techniques

• A system development life cycle is one of many models.
• Analysts have a wide variety of aids beyond SDLC.
• System development methodology provides guidelines every activity in system development.
• System development methodology includes specific models, tools, and techniques.
• UP is a system development methodology.
• A process is a synonym for a methodology.
• Methodologies supported with documentation

Models

• Models abstract aspects of the real world and come in many forms.
• Models can be physical analogs, mathematical, or graphical.
• System development models are highly abstract.
• Models Depict inputs, outputs, processes, data, objects, interactions, locations, networks, and devices
• Unified Modeling Language (UML) is a standard notation.
• PERT or Gantt charts model the project itself.

Models of system components using UML:

• Use case diagram
• Class diagram
• Activity diagram
• Sequence diagram
• Communication diagram
• Package diagram

Models used to manage development process:

• PERT chart
• Gantt chart
• Organization hierarchy chart
• Financial analysis models (net present value, return on investment)

Tools

• Tools are software used to create models or components such as:
  • Project management software tools (Microsoft Project)
  • Integrated development environments (IDEs)
  • Code generators
  • Computer-aided system engineering (CASE)

Techniques

• A technique is a collection of guidelines.
• They enable an analyst complete an activity or task.
• Example techniques:
  • Domain-modeling, use case modeling, software-testing
  • User-interviewing techniques
  • Relational database design techniques
• Proven techniques are embraced as "Best Practices".

The Unified Process as a System Development Methodology

• UP is an object-oriented system development methodology.
• UP should be tailored to organizational and project needs.
• Project will be use case driven
• Barbara Halifax selects a "lighter" UP variation for RMO's customer support system project
• Use case is an activity that the system carries out
• Use cases are the basis for defining requirements and designs
• UP defines disciplines within each phase
• Discipline can be defined as a set of functionally related activities
• Iterations concatenate activities from all disciplines
• Activities in each discipline produce artifacts; models, documents, source code, and executables

The UP Disciplines

• There are six main UP development disciplines:
  • Business modeling
  • Requirements
  • Design
  • Implementation
  • Testing
  • Deployment
• Each iteration is similar to a mini-project.
• Each iteration results in a completed portion of the system.
• The three additional support disciplines:
  • Project management
  • Configuration and change management
  • Environment

The Nine Core Disciplines

• Business Modeling: Re-envision and Re-engineering the Organization
• Requirements: Define the User Requirements
• Design: Design the system
• Implementation: Write the software
• Test: Test the system
• Deployment: Integrate the software to the using organization
• Configuration and Change Management: Manage the artifacts of the evolving system
• Project Management: Manage the development process
• Environment: Support the development process with processes and tools

Project Management

• This is the most important support discipline
• Project management activities include:
  • Finalize the system and project scope
  • Develop the project and iteration schedule
  • Identify project risks and confirm feasibility
  • Monitor and control the project's plan
  • Monitor and control communications
  • Monitor and control risks and outstanding issues

Configuration and Change Management

• Configuration and change discipline pertains to:
  • Requirements
  • Design
  • Source code
  • Executables
• The two activities in this discipline:
  • Develop change control procedures
  • Manage models and software components

Environment

• The Development environment includes:
  • Available facilities
  • Design of the workspace
  • Forums for team communication and interaction
• Environment discipline activities:
  • Select and configure the development tools
  • Tailor the UP development process
  • Provide technical support services

Overview of Object-Oriented Concepts

• OOA views system as a collection of objects
• An Object is an entity capable of responding to messages
• Languages: Simula, C++, Java, C#, Visual Basic .NET
• Object-oriented design (OOD) defines additional types of communication objects
• OOD shows how the objects interact to complete tasks
• OOD refines definition of objects for implementation
• Object-oriented programming (OOP) is object coding

Recognizing the Benefits of OO Development

• Original application of object-oriented technology:
  • Computer simulations
  • Graphical user interfaces
• Rationale for use in information systems:
  • Benefits of naturalness
  • Reusability

Objects Are More Natural

• OO approach mirrors human perception: objects moving through space
• OOA, OOD, and OOP imitate perceptual processes by modeling classes of objects
• Some system developers resist OO development
• New programmers are more receptive to OO approach
• System users appreciate object-orientation
  • They discuss the objects involved in their work
  • Hierarchies are common tools for organizing knowledge

Classes of Objects Can Be Reused

• Classes of objects have a long shelflife
• Example: Customer class adaptability
  • Reused in systems where customer objects needed
  • Extended through inheritance to a new subclass
  • Reused during analysis, design, or programming
• Classes may be stored, with implementation hidden, in class libraries

Understanding Object-Oriented Concepts

• Object: thing with attributes and behaviors
• Types of objects:
  • User interface
  • Problem domain objects
• Attributes are associated with data
• Behaviors are associated with methods, functions, and procedures
• Class: defines what all objects of class represent
• Objects are instances of a class
• Customer object is an instance of a customer class
• Objects interact through messages
• Objects retain memory of transactions

Abstract and Concrete Classes

• Classes that can be instantiated into actual (real or virtual) objects are called concrete classes.
• Classes that cannot be instantiated into actual (real or virtual) objects are abstract classes.

Key Object-Oriented Concepts:

• Objects maintain association relationships
• Encapsulation: combining attributes and methods into one unit
• Information hiding: separating specification from implementation
• Inheritance: extending the characteristics of a class
• Polymorphism: ability for dissimilar objects to respond to the same message
• Association provides a linkage between objects of given classes
• Inheritance is a generalization relationship between a more generic class (superclass or parent) and a more specialized kind of that class (subclass or child)

Tools to Support System Development

• CASE (Computer Aided System Engineering) is one of them
• CASE includes a Database repository for information system + a set of tools that help analysts complete activities + sample artifacts: models, automatically generated code
• Variations on CASE:
  • Visual modeling tools
  • Integrated application development tools
  • Round-trip engineering tools
• Microsoft Visio: emphasizes technical drawing
• Rational Rose: CASE tool supporting object-oriented approach, and strongly identified with UP methodology
• Together pioneers round-trip engineering, synchronizes graphical models with generated program code, and leverages UML diagrams
• Embarcadero Describe: Visual Modeling and Round-trip engineering
• Rational XDE Professional integrates Microsoft Visual Studio.NET IDE + Also provides visual modeling and round-trip

Summary

• SDLC: set of activities required to complete system development project
• Predictive SDLC: executes project in sequential phases (waterfall approach)
• Adaptive SDLC: accommodates change and phase overlap
• Spiral SDLC model introduces iterations (cycles)
• UP is an adaptive system development methodology
• UP life cycle includes four phases-inception, elaboration, construction, and transition
• UP Phases are decomposed into one or more iterations
• Iterations involve work in nine UP disciplines
• UP itself is object-oriented
• Object-oriented concepts: object, class, methods, encapsulation, associations, inheritance, polymorphism
• CASE: automation tools simplify development tasks