INTRODUCTION TO UML
INTRODUCTION TO UMLLe Trung HieuOverview of UMLUnified Modeling
Language (UML) is a standard language for creating blueprint that
depicts structure and design of the software system. You can use
UML for modeling systems that can range between enterprise
information systems to distributed Web-based applications. There
are several tools available, such as Rational Rose, Jude, AgroUML,
and Poseidon, which you can use to design software systems by using
UML.
Evolution of UMLDuring the mid 1970s and late
1980s:Object-oriented modeling languages were developed for
analysis and design of the software. The most prominently used
languages were:Boochs Booch93 Jacobsons Object Oriented Software
Engineering (OOSE)Rumbaughs Object Modeling Technique-2 (OMT).In
October 1994, the unification of Booch93, OMT, and OOSE led to the
release of version 0.9 and 0.91 of UML.
Scope of UMLRational Software Corporation defines UML as
follows: The Unified Modeling Language (UML) is a language for
specifying, constructing, visualizing, and documenting the
artifacts of a software-intensive system.Artifacts include
requirements, architecture, design in terms of classes, objects or
interfaces, source code, tests, prototypes, and the software
releases of a software system. A software-intensive system includes
high-end enterprise solutions, such as:Banking servicesDistributed
Web-based servicesMedical systemsInsurance
Defining UML Notations UML provides the following nine diagrams
to represent the structure and design of a software system:Use case
diagramsClass diagramsObject diagrams Collaboration diagrams
Sequence diagrams State diagrams Activity diagrams Component
diagrams Deployment diagrams
Defining Use Case DiagramsA use case diagram:Depicts the various
operations that a system performs. Contains use cases, actors, and
their relationships.
Defining Class DiagramsA class diagram represents a set of
classes, interfaces, and their relationships.
Defining Object DiagramsAn object diagram represents an instance
of a class diagram.
Defining Collaboration DiagramsCollaboration diagrams represent
interaction between objects in the form of messages.
Defining Sequence DiagramsSequence diagrams represent
interaction between objects in the form of messages ordered in
sequence by time.
Defining State DiagramsA state diagram shows how a class reacts
when an event occurs.
Defining Activity DiagramsActivities are a representation of
various operations performed by a class. An activity diagram
depicts the flow of control from one activity to another.
Defining Component DiagramsYou combine packages or individual
entities to form components. A component diagram depicts various
components and their dependencies.
Defining Deployment DiagramsA deployment diagram shows the
physical placement of components in nodes over a network.
Associating UML Diagrams with UML Modeling TechniquesThe four
modeling techniques are:Requirements modeling: Involves depicting
the requirements using use case diagrams. Static modeling: Involves
depicting the static constituents of the software system using the
class and object diagrams.Dynamic modeling: Involves depicting the
behavior of static constituents using the following diagrams:
Collaboration diagramSequence diagramActivity diagramState diagram
Architectural modeling: Involves depicting the architecture of the
software system into multiple tiers, such as presentation,
business, and resource.
Viewing a Software System ArchitectureThe architecture of a
software system is defined as an arrangement of the static and
dynamic constituents in a model. The various views of a software
system are:Use case view: Indicates the functionalities that the
system offers to each stakeholder. Design view: Focuses on the
static and dynamic representation of the system. Process view:
Represents various processes executing in a system at a given
instance of time. Implementation view: Represents the physical
system including files and components required to assemble the
system. Deployment view: Represents the hardware components on
which the software system will execute.
Viewing a Software System Architecture
The Role of UML in SDLCDiagrams developed using UML serve as key
documents in each phase of SDLC.The following table lists the UML
diagrams that the end users can use in the requirement analysis
phase:
Diagram
Role of a Diagram in the Requirement Analysis Phase
Use case
Depicts the various users of the system and how they are going
to use the system to meet the requirement objectives
Class
Depicts the classes and their dependencies for the primary
requirements of the system
Sequence and Collaboration
Depicts the sequence of steps performed in a process
Activity
Depicts the specific activities that are required to understand
the functional requirements of the system
The Role of UML in SDLC
The following table lists various UML diagrams that you can use
in the design phase:
Diagram
Role of a Diagram in SDLC phase
Class
Depicts the classes, their attributes and operations, and the
relationship between classes
Sequence
Depicts the sequence of interactions between the various objects
of the system
Package
Depicts the various classes that are grouped together depending
on their functionality
Deployment
Depicts the layout of the software components over the
network
State
Depicts the state of an object on the occurrence of an event
Component
Depicts the components required for executing system
The Role of UML in SDLCYou use the use case diagram in the test
phase. The use case diagram depicts the test cases on the basis of
which the system is tested.
