Introduction to UML & its Diagrams · Origin of UML Three prominent methodologists in IS and IT...

Introduction to UML & its Diagrams

By Miiro Edward_Dpt of Business Computing

In this presentation

•Modeling principles

•Xtics of a modeling language

•The Unified Modeling Language

(UML)

•Elements of the UML

•Origin of UML

•Organisational overview of UML

•UML Diagrams


Modeling Principles

There are four basic principles of modeling

• The choice of the model is important ie the

diagrams to be used

• The level of precision may differ in details

• Models are connected to reality…must

support reality

• No single model is sufficient


Xtics of a modeling language

• A modeling language consists of notation

(the symbols used in the models) and a set

of rules directing how to use it….syntactic,

semantic, and pragmatic

• Syntax rules: tells us how the symbols should

look and how they are combined

• Semantic rules: explain what each symbol

means and how it should be interpreted.

• The pragmatic rules: define the intentions of

the symbols through which the purpose of

a model is achieved.


The Unified Modeling Language

• It is an OOL for specifying, visualizing,

constructing, and documenting the

artifacts of software systems.

• It is represented by many diagrams.

• It is a visual modeling language not a visual

programming language.

• It is used for graphically depicting OOA

and design models.


Before UML……

• There were multitude of different methods,

each with its own unique notation and tools

• This left many developers confused and

unable to collaborate.

• Most of the early object-oriented methods

were immature and best suited for small

systems with limited functionality


Origin of UML Three prominent methodologists in IS and IT

industry;

• Grady Booch

• James Rumbaugh

• Ivar Jacobson

• A primary goal of UML was to put an end to

the “method wars” within the OO

community….supported by the OMG

• In 1997, Version 1.0 of the UML was released

and in 2004 UML v2 was released.


Organisational overview of UML

• Views: These show different aspects of the

system.

• Diagrams: Graphical elements that

describe the contents in a view

• Model elements: Concepts used in the

diagrams eg classes, objects, messages

and their relationships

• General mechanisms: These provide extra

comments, information, or semantics for a

model element


Views • Use-case view. Shows the functionality of

the system as perceived by external actors.

• Logical view. Shows the functionality as

designed inside the system

• Implementation view. Shows the

organization of the code and the actual

execution code.

• Process view. Shows the main elements in

the system related to process performance

eg time,scalability

• Deployment view. Shows the deployment

of the system into the environment.


Two things before we start modeling

•OO Analysis: we identify

objects and their relationships

•OOD: We collaborate the

objects and the relationships

into a design


• It illustrates a unit of functionality provided

by the system.

• Its main aim is to help the development

teams visualize the functional requirements

of the system including the actors to

essential processes as well as the

relationships among the different use cases

• A use case is typically used to

communicate the high level functions of

the system and system scope.


Use case diagram

Example…..Course Mgt system


Class diagrams

• Shows how the different entities (people,

things, data) relate to each other. In other

words it shows the static nature of the

system.

• It can be used to show the logical classes

which are typically the things business

people talk about in an organization eg

interest rates, home morgages etc


Example…


Object diagram

• A variant of a class diagram and uses

almost identical notation.

• It shows a number of object instances of

classes, instead of the actual classes


Behavioral diagrams

They describe behavior of the

software objects.

There are basically four diagrams ie

•Sequence diagrams

•Activity diagrams

•State chart diagrams

•Deployment diagrams


Sequence Diagram • Show the succession of interactions over

time between system objects through

exchange of messages

• It shows a sequence of messages sent

between the objects.

• It also shows an interaction between

objects, something that happens at one

specific point in the execution of the system


Example…


Activity diagrams

• These show the flow of activities within a

software system process

• They show a business process or a software

process as a flow of work or a series of

actions eg a flow of work between the

users and the system

• The steps performed in the use case

• A software protocol ie the permitted

sequence of interactions among

components


Example


State chart diagram

• A state chart is a complement to the

description of a class.

• It shows the states of an object plus the

events and conditions that trigger the

transitions from one state to the other

• It shows all the possible states that objects

of the class can have during a life-cycle

instance, and which events cause the state

to change.

• An event can be triggered by another

object that sends a message to it. By Miiro Edward_Dpt of Business Computing

Deployment Diagram

• Show the deployment of the software in a

specific environment

• Shows the physical architecture of the

hardware and software in the system.

• You can show the actual computers and

devices (nodes), along with the

connections they have to each other;

• You can also show the type of

connections.


Introduction to UML & its Diagrams · Origin of UML Three prominent methodologists in IS and IT...

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