slide 1 objectives understand the basic characteristics of object-oriented systems. be familiar...
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Slide 1
ObjectivesUnderstand the basic characteristics of object-oriented systems.Be familiar with the Unified Modeling Language (UML),V.2.0.
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Non-Object-Oriented…Process models
Based on behaviour and actionsData Models
Based on static (fixed) representations of data
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A “Simple” Process for Making Lunch
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Process Modelling:
Data Flow Diagrams
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Reading a DFD
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Data Modelling:
Entity-Relationship Diagrams (ERDs)
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What Is an ERD?A picture showing the information created, stored, and used by a business system. Entities generally represent people, places, and things of interest to the organization.Lines between entities show relationships between entities.
Copyright 2005 John Wiley & Sons, Inc. All rights reserved.PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design
Copyright 2001 © John Wiley & Sons, Inc. All rights reserved.
An ERD Example
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Entities and Instances
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Object-Oriented ApproachesCombine processes and dataAre more ‘natural’
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Basic Characteristics of Object Oriented Systems
Classes and ObjectsMethods and MessagesEncapsulation and Information HidingInheritancePolymorphism
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Helpful Hint….’Compile’C ClassesO Objects M Methods and MessagesP Polymorphism I Inheritance(Last, but not least)E Encapsulation
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Classes and ObjectsClass – Template to define specific instances or objectsObject – Instantiation of a classAttributes – Describes the objectBehaviours – specify what object can do
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Classes and Objects
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Methods and MessagesMethods implement an object’s behaviour
Analogous to a function or procedure
Messages are sent to trigger methods
Procedure call from one object to the next
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Messages and Methods
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Encapsulation and Information Hiding
Encapsulation combination of data and process into an entity
Information HidingOnly the information required to use a software module is published to the user
Reusability is the Key Pointan object is used by calling methods
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InheritanceSuperclasses or general classes are at the top of a hierarchy of classesSubclasses or specific classes are at the bottomSubclasses inherit attributes and methods from classes higher in the hierarchy
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Class Hierarchy
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Inheritance
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PolymorphismA message can be interpreted differently by different classes of objects
e.g. A ‘Create_Record’ message is essentially the same thing, but causes ‘Create_Patient_Record’ by a ‘Patient_Database’ object, or ‘Create_Doctor_Record’ by a ‘Healthcare_Staff_Database’ object
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Polymorphism & Encapsulation
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Benefits of the Object Approach
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The Unified Modelling Language, Version 2.0
Functional DiagramsStructure DiagramsBehaviour Diagrams
Developers Grady Booch Ivar Jacobson James Rumbaugh
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Functional DiagramsActivity Diagrams
Illustrate business workflowsUse-Case Diagrams
Capture business requirementsIllustrates interaction between system and environment
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Structure DiagramsClass diagrams
relationship between classesObject diagrams
Relationships between objects
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Behaviour DiagramsInteraction Diagrams ....
Sequence diagrams Show Time-based ordering and behaviour
of objects and their activitiesState Machines ...
Behavioural State Machines (Statechart diagrams)
Examines behaviour of one class/object
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Object Oriented Systems Analysis and Design• Use-case driven• Iterative and Incremental• Often associated with PHASED
Development (a RAD methodology)
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Basic Method for Development of Object Oriented Systems
Identifying business valueAnalyze feasibilityDevelop workplanStaff the projectControl and direct projectRequirements determinationFunctional modellingStructural modellingBehavioural modellingMoving on to design
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SummaryProcess oriented (Data flow diagrams) and Data oriented (Entity relationship diagrams)Basic characteristics of Object Oriented Systems Analysis and DesignIntroduction to Unified Modelling Language and the Unified Process
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