conceptual model of the uml

8/6/2019 Conceptual Model of the Uml

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CONCEPTUAL MODEL OF THE UML:

To understand the UML, we need to form a conceptual model of the

language and this requires learning three major elements.

The UML Basic Building Blocks.

The Rules that direct how those building blocks may be put together.

Some common mechanisms that apply throughout the UML.

As UML describes the real time systems it is very important to make a

conceptual model and then proceed gradually. Conceptual model of UMLcan be mastered by learning the following three major elements:

UML BUILDING BLOCKS:

Rules to connect the building blocksCommon mechanisms of UML

This chapter describes all the UML building blocks. The building blocks

of UML can be defined as:

Things

Relationships

Diagrams

THINGS:

Things are the most important building blocks of UML. Things can be:

Structural

Behavioral


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GroupingAn notational

STRUCTURAL THINGS:

The Structural things define the static part of the model. They represent

physical and conceptual elements. Following are the brief descriptions of

the structural things.

CLASS:

Class represents set of objects having similar responsibilities.

INTERFACE:

Interface defines a set of operations which specify the responsibility of aclass.

COLLABORATION:

Collaboration defines interaction between elements.


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USE CASE:

Use case represents a set of actions performed by a system for a specificgoal.

COMPONENT:

Component describes physical part of a system .

NODE:

A node can be defined as a physical element that exists at run time.

BEHAVIORAL THINGS:

Abehavioral thing consists of the dynamic parts of UML models.Following are the behavioral things:


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INTERACTION:

Interaction is defined as a behavior that consists of a group of messagesexchanged among elements to accomplish a specific task.

STATE MACHINE:

State machine is useful when the state of an object in its life cycle is

important. It defines the sequence of states an object goes through in

response to events. Events are external factors responsible for state

change.

GROUPING THINGS:

Grouping things can be defined as a mechanism to group elements of a

UML model together. There is only one grouping thing available.

PACKAGE:

Package is the only one grouping thing available for gathering structuraland behavioral things.


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ANNOTATIONAL THINGS:

Annotational things can be defined as a mechanism to capture remarks,

descriptions, and comments of UML model elements. Note is the only

one Annotational thing available.

Note:

A note is used to render comments, constraints etc of an UML element.

RELATIONSHIP IN UML

Relationship is another most important building block of UML. It shows

how elements are associated with each other and this association

describes the functionality of an application.

There are four kinds of relationships available.

DEPENDENCY:

Dependency is a relationship between two things in which change in one

element also affects the other one.


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ASSOCIATION:

Association is basically a set of links that connects elements of an UML

model. It also describes how many objects are taking part in that

relationship.

GENERALIZATION:

Generalization can be defined as a relationship which connects a

specialized element with a generalized element. It basically describes

inheritance relationship in the world of objects.

REALIZATION:

Realization can be defined as a relationship in which two elements are

connected. One element describes some responsibility which is not

implemented and the other one implements them. This relationship exists

in case of interfaces.


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UML DIAGRAMS

UML diagrams are the ultimate output of the entire discussion. All the

elements, relationships are used to make a complete UML diagram and

the diagram represents a system.

The visual effect of the UML diagram is the most important part of the

entire process. All the other elements are used to make it a complete one.

UML includes the following nine diagrams and the details are described

in the following chapters.

Class diagram

Object diagram

Use case diagram

Sequence diagram

Collaboration diagramActivity diagram

State chart diagram

Deployment diagram

Component diagram

CLASS DIAGRAM


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OVERVIEW:

The class diagram is a static diagram. It represents the static view of an

application. Class diagram is not only used for visualizing, describing and

documenting different aspects of a system but also for constructing

executable code of the software application.

The class diagram describes the attributes and operations of a class and

also the constraints imposed on the system. The class diagrams are widely

used in the modeling of object oriented systems because they are the only

UML diagrams which can be mapped directly with object oriented

languages.

The class diagram shows a collection of classes, interfaces, associations,

collaborations and constraints. It is also known as astructural diagram .

PURPOSE:


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The purpose of the class diagram is to model the static view of an

application. The class diagrams are the only diagrams which can be

directly mapped with object oriented languages and thus widely u sed at

the time of construction.

The UML diagrams like activity diagram, sequence diagram can only

give the sequence flow of the application but class diagram is a bit

different. So it is the most popular UML diagram in the coder

community.

So the purpose of the class diagram can be summarized as:

Analysis and design of the static view of an application.

Describe responsibilities of a system.

Base for component and deployment diagrams.

Forward and reverse engineering.

How to draw Class Diagram?


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Class diagrams are the most popular UML diagrams used for construction

of software applications. So it is very important to learn the drawing

procedure of class diagram.

Class diagrams have lot of properties to consider while drawing but here

the diagram will be considered from a top level view.

Class diagram is basically a graphical representation of the static view of

the system and represents different aspects of the application. So a

collection of class diagrams represent the whole system.

The following points should be remembered while drawing a class

diagram:

The name of the class diagram should be meaningful to describe the

aspect of the system.

Each element and their relationships should be identified in advance.

Responsibility (attributes and methods) of each class should be clearly

identified.

For each class minimum number of properties should be specified.

Because unnecessary properties will make the diagram complicated.

Use notes when ever required to describe some aspect of the diagram.

Because at the end of the drawing it should be understandable to the

developer/coder.

Finally, before making the final version, the diagram should be drawn on

plain paper and rework as many times as possible to make it correct.

Now the following diagram is an example of an Order System of an

application. So it describes a particular aspect of the entire application.

First of all Orderand Customerare identified as the two elements of the

system and they have a one to many relationship because a customer can

have multiple orders.

We would keep Orderclass is an abstract class and it has two concrete

classes (inheritance relationship) SpecialOrderandNormalOrder.


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The two inherited classes have all the properties as the Orderclass. In

addition they have additional functions like dispatch () and receive ().

So the following class diagram has been drawn considering all the points

mentioned above:

Where to use Class Diagrams?

Class diagram is a static diagram and it is used to model static view of a

system. The static view describes the vocabulary of the system.Class diagram is also considered as the foundation for component and

deployment diagrams. Class diagrams are not only used to visualize the

static view of the system but they are also used to construct the

executable code for forward and reverse engineering of any system.


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Generally UML diagrams are not directly mapped with any object

oriented programming languages but the class diagram is an exception.

Class diagram clearly shows the mapping with object oriented languages

like Java, C++ etc. So from practical experience class diagram is

generally used for construction purpose.

So in a brief, class diagrams are used for:

Describing the static view of the system.

Showing the collaboration among the elements of the static view.

Describing the functionalities performed by the system.

Construction of software applications using object oriented

languages.

OBJECT DIAGRAM:

Object diagram shows a set of objects and there

relationships.Object diagram represents static snapshot of

instances of the things found in class diagram.

These diagrams addresses static design view or staticprocess view of a system.

USE CASE DIAGRAM

OVERVIEW:

To model a system the most important aspect is to capture the dynamic

behaviour. To clarify a bit in details, dynamic behaviourmeans the

behaviour of the system when it is running /operating.


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So only static behaviour is not sufficient to model a system rather

dynamic behaviour is more important than static behaviour. In UML

there are five diagrams available to model dynamic nature and use case

diagram is one of them. Now as we have to discuss that the use case

diagram is dynamic in nature there should be some internal or external

factors for making the interaction.

These internal and external agents are known as actors. So use case

diagrams are consists of actors, use cases and their relationships. The

diagram is used to model the system/subsystem of an application. A

single use case diagram captures a particular functionality of a system.

So to model the entire system numbers of use case diagrams are used.

PURPOSE:

The purpose of use case diagram is to capture the dynamic aspect of a

system. But this definition is too generic to describe the purpose.

Because other four diagrams (activity, sequence, collaboration and

Statechart) are also having the same purpose. So we will look into some

specific purpose which will distinguish it from other four diagrams.

Use case diagrams are used to gather the requirements of a system

including internal and external influences. These requirements are mostly

design requirements. So when a system is analyzed to gather its

functionalities use cases are prepared a nd actors are identified.

Now when the initial task is complete use case diagrams are modelled to

present the outside view.So in brief, the purposes of use case diagrams can be as follows:

Used to gather requirements of a system.

Used to get an outside view of a system.

Identify external and internal factors influencing the system.


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Show the interacting among the requirements are actors.

How to draw Component Diagram?

Use case diagrams are considered for high level requirement analysis of a

system. So when the requirements of a system are analyzed the

functionalities are captured in use cases.

So we can say that uses cases are nothing but the system functionalities

written in an organized manner. Now the second things which are

relevant to the use cases are the actors. Actors can be defined as

something that interacts with the system.

The actors can be human user, some internal applications or may be some

external applications. So in a brief when we are planning to draw an use

case diagram we should have the following items identified.

Functionalities to be represented as an use case Actors

RELATIONSHIPS AMONG THE USE CASES AND

ACTORS.

Use case diagrams are drawn to capture the functional requirements of a

system. So after identifying the above items we have to follow the

following guidelines to draw an efficient use case diagram.

The name of a use case is very important. So the name should be chosen

in such a way so that it can identify the functionalities performed.Give a suitable name for actors.

Show relationships and dependencies clearly in the diagram.

Do not try to include all types of relationships. Because the main purpose

of the diagram is to identify requirements.


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Use note when ever required to clarify some important points.

The following is a sample use case diagram representing the order

management system. So if we look into the diagram then we will find

three use cases (Order, SpecialOrder and NormalOrder) and one actor

which is customer.

The SpecialOrderandNormalOrderuse cases are extended from Order

use case. So they have extends relationship. Another important point is to

identify the system boundary which is shown in the picture. The actor

Customerlies outside the system as it is an external user of the system.


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INTERACTION DIAGRAM

We have two types of interaction diagrams in UML. One is sequence

diagram and the other is a collaboration diagram. The sequence diagram

captures the time sequence of message flow from one object to another

and the collaboration diagram describes the organization of objects in a

system taking part in the message flow.


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So the following things are to identified clearly before drawing the

interaction diagram:

Objects taking part in the interaction.

Message flows among the objects.

The sequence in which the messages are flowing.

Object organization.

Following are two interaction diagrams modeling order management

system. The first diagram is a sequence diagram and the second is a

collaboration diagram.

THE SEQUENCE DIAGRAM:

The sequence diagram is having four objects (Customer, Order,

SpecialOrder and NormalOrder).

The following diagram has shown the message sequence for

SpecialOrderobject and the same can be used in case ofNormalOrder

object. Now it is important to understand the time sequence of message

flows. The message flow is nothing but a method call of an object.


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The first call issendOrder () which is a method ofOrderobject. The next

call is confirm () which is a method ofSpecialOrderobject and the last

call isDispatch () which is a method ofSpecialOrderobject. So here the

diagram is mainly describing the method calls from one object to another

and this is also the actual scenario when the system is running.

THE COLLABORATION DIAGRAM:

The second interaction diagram is collaboration diagram. It shows the

object organization as shown below. Here in collaboration diagram the

method call sequence is indicated by some numbering technique as

shown below. The number indicates how the methods are called one after

another. We have taken the same order management system to describe

the collaboration diagram.

The method calls are similar to that of a sequence diagram. But the

difference is that the sequence diagram does not desc ribe the object

organization where as the collaboration diagram shows the object

organization.


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Now to choose between these two diagrams the main emphasis is given

on the type of requirement. If the time sequence is important then

sequence diagram is used and if organization is required then

collaboration diagram is used.

Where to use Interaction Diagrams?

we have already discussed that interaction diagrams are used to describe

dynamic nature of a system. now we will look into the practical scenarios

where these diagrams are used. to understand the practical application we

need to understand the basic nature of sequence and collaboration

diagram.

the main purposes of both the diagrams are similar as they are u sed to

capture the dynamic behaviour of a system. but the specific purposes are

more important to clarify and understood.

sequence diagrams are used to capture the order of messages flowing

from one object to another. and the collaboration diagrams are use d to

describe the structural organizations of the objects taking part in the

interaction. a single diagram is not sufficient to describe the dynamic


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aspect of an entire system so a set of diagrams are used to capture is as a

whole.

the interaction diagrams are used when we want to understand the

message flow and the structural organization. now message flow means

the sequence of control flow from one object to another and structural

organization means the visual organization of the elements in a system.

in a brief the following are the usages of interaction diagrams:

to model flow of control by time sequence.

to model flow of control by structural organizations.

for forward engineering.

for reverse engineering.

STATE CHART DIAGRAM

OVERVIEW:

The name of the diagram itself clarifies the purpose of the diagram and

other details. It describes different states of a component in a system. The

states are specific to a component/object of a system.

A State chart diagram describes a state machine. Now to clarify it state

machine can be defined as a machine which defines different states of an

object and these states are controlled by external or internal events.

Activity diagram explained in next chapter, is a special kind of a State

chart diagram. As State chart diagram defines states it is used to model

lifetime of an object.

PURPOSE:


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Statechart diagram is one of the five UML diagrams used to model

dynamic nature of a system. They define different states of an object

during its lifetime. And these states are changed by events. So Statechart

diagrams are useful to model reactive systems. Reactive systems can be

defined as a system that responds to external or internal events.

Statechart diagram describes the flow of control from one state to another

state. States are defined as a condition in which an object exists and it

changes when some event is triggered. So the most important purpose of

Statechart diagram is to model life time of an object from creation to

termination.

Statechart diagrams are also used for forward and reverse engineering of

a system. But the main purpose is to model reactive system.

Following are the main purposes of using State chart diagrams:

To model dynamic aspect of a system.

To model life time of a reactive system.

To describe different states of an object during its life time.

Define a state machine to model states of an object .


State chart diagram is used to describe the states of different objects in its

life cycle. So the emphasis is given on the state changes upon some

internal or external events. These states of objects are important to

analyze and implement them accurately.

State chart diagrams are very important for describing the states. States

can be identified as the condition of objects when a p articular event

occurs.

Before drawing a State chart diagram we must have clarified the

following points:


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Identify important objects to be analyzed.Identify the states.

Identify the events.

The following is an example of a State chart diagram where the st ate of

Orderobject is analyzed.

The first state is an idle state from where the process starts. The next

states are arrived for events like send request, confirm request, and

dispatch order. These events are responsible for state changes of order

object.

During the life cycle of an object (here order object) it goes through the

following states and there may be some abnormal exists also. This

abnormal exit may occur due to some problem in the system. When the

entire life cycle is complete it is considered as the complete transaction as

mentioned below.

The initial and final state of an object is also shown below.


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From the above discussion we can define the practical applications of a

Statechart diagram. Statechart diagrams are used to model dynamic

aspect of a system like other four diagrams disused in this tutorial. But it

has some distinguishing characteristics for modeling dynamic nature.

Statechart diagram defines the states of a component and these s tate

changes are dynamic in nature. So its specific purpose is to define state

changes triggered by events. Events are internal or external factors

influencing the system.

Statechart diagrams are used to model states and also events operating on

the system. When implementing a system it is very important to clarify

different states of an object during its life time and statechart diagrams

are used for this purpose. When these states and events are identified they

are used to model it and these models are u sed during implementation of

the system.

If we look into the practical implementation of Statechart diagram then it

is mainly used to analyze the object states influenced by events. This

analysis is helpful to understand the system behaviour during its

execution.


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So the main usages can be described as:

To model object states of a system.

To model reactive system. Reactive system consists of reactive

objects.

To identify events responsible for state changes.

Forward and reverse engineering.

ACTIVITY DIAGRAM

OVERVIEW:

Activity diagram is another important diagram in UML to describe

dynamic aspects of the system.

Activity diagram is basically a flow chart to represent the flow form one

activity to another activity. The activity can be described as an operation

of the system.

So the control flow is drawn from one operation to another. This flow can

be sequential, branched or concurrent. Activity diagrams deals with all

type of flow control by using different elements like fork, join etc.

PURPOSE:

The basic purposes of activity diagrams are similar to other four

diagrams. It captures the dynamic behaviour of the system. Other four

diagrams are used to show the message flow from one object to anotherbut activity diagram is used to show message flow from one activity to

another.

Activity is a particular operation of the system. Activity diagrams are not

only used for visualizing dynamic nature of a system but they are also


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Once the above mentioned parameters are identified we need to make a

mental layout of the entire flow. This mental layout is then transformed

into an activity diagram.

The following is an example of an activity diagram for order management

system. In the diagram four activities are identified which are associated

with conditions. One important point should be clearly understood that an

activity diagram cannot be exactly matched with the code. The activity

diagram is made to understand the flow of activities and mainly used by

the business users.

The following diagram is drawn with the four main activities:

Send order by the customer

Receipt of the order

Confirm order

Dispatch order

After receiving the order request condition checks are performed to check

if it is normal or special order. After the type of order is identified

dispatch activity is performed and that is marked as the termination of the

process.


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The basic usage of activity diagram is similar to other four UML

diagrams. The specific usage is to model the control flow from one

activity to another. This control flow does not include messages.

The activity diagram is suitable for modeling the activity flow of the

system. An application can have multiple systems. Activity diagram also

captures these systems and describes flow from one system to another.

This specific usage is not available in other diagrams. These systems can

be database, external queues or any other system.

Now we will look into the practical applications of the activity diagram.

From the above discussion it is clear that an activity diagram is drawn

from a very high level. So it gives high level view of a system. This high

level view is mainly for business users or any other person who is not a

technical person.


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This diagram is used to model the activities which are nothing but

business requirements. So the diagram has more impact on business

understanding rather implementation details.

Following are the main usages of activity diagram:

Modeling work flow by using activities.

Modeling business requirements.

High level understanding of the system's functionalities.

Investigate business requirements at a later stage.

COMPONENT DIAGRAM

OVERVIEW:

Component diagrams are different in terms of nature and behaviour.

Component diagrams are used to model physical aspects of a system.

Now the question is what are these physical aspects? Physical aspects are

the elements like executables, libraries, files, documents etc which resides

in a node.

So component diagrams are used to visualize the organization and

relationships among components in a system. These diagrams are also

used to make executable systems.

PURPOSE:

Component diagram is a special kind of diagram in UML. The purpose is

also different from all other diagrams discussed so far. It does not


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describe the functionality of the system but it describes the components

used to make those functionalities.

So from that point component diagrams are used to visualize the physical

components in a system. These components are libraries, packages, files

etc.

Component diagrams can also be described as a static implementation

view of a system. Static implementation represents the organization of the

components at a particular moment.

A single component diagram cannot represent the entire system but a

collection of diagrams are used to represent the whole.

So the purpose of the component diagram can be summarized as:

Visualize the components of a system.

Construct executables by using forward and reverse engineering.

Describe the organization and relationships of the components.


Component diagrams are used to describe the physical artifacts of a

system. This artifact includes files, executables, libraries etc.

So the purpose of this diagram is different, Component diagrams are used

during the implementation phase of an application. But it is prepared well

in advance to visualize the implementation details.

Initially the system is designed using different UML diagrams and then

when the artifacts are ready component diagrams are used to get an idea

of the implementation.

This diagram is very important because without it the application cannot

be implemented efficiently. A well prepared component diagram is also

important for other aspects like application performance, maintenance

etc.


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So before drawing a component diagram the following artifacts are to be

identified clearly:

Files used in the system.

Libraries and other artifacts relevant to the application.

Relationships among the artifacts.

Now after identifying the artifacts the following points needs to be

followed:

Use a meaningful name to identify the component for which the

diagram is to be drawn.

Prepare a mental layout before producing using tools.

Use notes for clarifying important points.

The following is a component diagram for order management system.

Here the artifacts are files. So the diagram shows the files in the

application and their relationships. In actual the c omponent diagram also

contains dlls, libraries, folders etc.

In the following diagram four files are identified and their relationships

are produced. Component diagram cannot be matched directly with other

UML diagrams discussed so far. Because it is drawn for completely

different purpose.

So the following component diagram has been drawn considering all the

points mentioned above:


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Component diagrams are very important from implementation

perspective. So the implementation team of an application should have a

proper knowledge of the component details.

Now the usage of component diagrams can be described as:

Model the components of a system.

Model database schema.

Model executables of an application.

Model system's source code.

DEPLOYMENT DIAGRAM

OVERVIEW:

Deployment diagrams are used to visualize the topology of the physical

components of a system where the software components are deployed.

So deployment diagrams are used to describe the static deployment view

of a system. Deployment diagrams consist of nodes and their

relationships.

PURPOSE:

The nameDeploymentitself describes the purpose of the diagram.

Deployment diagrams are used for describing the hardware components

where software components are deployed. Component diagrams and

deployment diagrams are closely related.

Component diagrams are used to describe the components and

deployment diagrams shows how they are deployed in hardware.


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UML is mainly designed to focus on software artifact s of a system. But

these two diagrams are special diagrams used to focus on software

components and hardware components.

So most of the UML diagrams are used to handle logical components but

deployment diagrams are made to focus on hardware topology of a

system. Deployment diagrams are used by the system engineers.

The purpose of deployment diagrams can be described as:

Visualize hardware topology of a system.

Describe the hardware components used to deploy software

components.

Describe runtime processing nodes.


Deployment diagram represents the deployment view of a system. It is

related to the component diagram. Because the components are deployed

using the deployment diagrams. A deployment diagram consists of nodes.

Nodes are nothing but physical hardwares used to deploy the application.

Deployment diagrams are useful for system engineers. An efficient

deployment diagram is very important because it controls the following

parameters

Performance

Scalability

Maintainability

Portability

So before drawing a deployment diagram the following artifacts should

be identified:

Nodes

Relationships among nodes.


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The following deployment diagram is a sample to give an idea of the

deployment view of order management system. Here we have shown

nodes as:

Monitor

Modem

Caching server

Server

The application is assumed to be a web based application which is

deployed in a clustered environment using server 1, server 2 and server 3.

The user is connecting to the application using internet. The control is

flowing from the caching server to the clustered environment.

So the following deployment diagram has been drawn considering all the

points mentioned above:


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Where to use Deployment Diagrams?

Deployment diagrams are mainly used by system engineers. These

diagrams are used to describe the physical components (hardwares), their

distribution and association.

To clarify it in details we can visualize deployment diagrams as the

hardware components/nodes on which software components reside.

Software applications are developed to model complex business

processes. Only efficient software applications are not sufficient to meet

business requirements. Business requirements can be described as to

support increasing number of users, quick response time etc.

To meet these types of requirements hardware components should be

designed efficiently and in a cost effective way.

Now a day's software applications are very complex in nature. Software

applications can be stand alone, web based, distributed, mainframe based

and many more. So it is very important to design the hardware

components efficiently.

So the usage of deployment diagrams can be described as follows:

To model the hardware topology of a system.

To model embedded system.

To model hardware details for a client/server system.

To model hardware details of a distributed application.

Forwar


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UML class is represented by the diagram shown below. The diagram

is divided into four parts.

The top section is used to name the class.

The second one is used to show the attributes of the class.

The third section is used to describe the operations performed by

the class.

The fourth section is optional to show any additional components.

Classes are used to represent objects. Objects can be anything having

properties and responsibility.

OBJECT NOTATION:


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The objectis represented in the same way as the class. The only

difference is the name which is underlined as shown below.

As object is the actual implementation of a class which is known as the

instance of a class. So it has the same usage as the class.

INTERFACE NOTATION:

Interface is represented by a circle as shown below. It has a name which

is generally written below the circle.

Interface is used to describe functionality without implementation.Interface is the just like a template where you define different functions

not the implementation. When a class implements the interface it also

implements the functionality as per the requirement.


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COLLABORATION NOTATION:

Collaboration is represented by a dotted eclipse as shown below. It has a

name written inside the eclipse.

Collaboration represents responsibilities. Generally responsibilities are in

a group.

USE CASE NOTATION:

Use case is represented as an eclipse with a name inside it. It may contain

additional responsibilities.

Use case is used to capture high level functionalities of a system.


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The usage of Final State Notation is to show the termination point of a

process.

Active class Notation:

Active class looks similar to a class with a solid border. Active class is

generally used to describe concurrent behaviour of a system.

Active class is used to represent concurrency in a system.

COMPONENT NOTATION:

A component in UML is shown as below with a name inside. Additional

elements can be added wherever required.


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Component is used to represent any part of a system for which UML

diagrams are made.

NODE NOTATION:

A node in UML is represented by a square box as shown below with a

name. A node represents a physical component of the system.

Node is used to represent physical part of a system like server, network

etc.

BEHAVIOURAL THINGS:

Dynamic parts are one of the most important elements in UML. UML has

a set of powerful features to represent the dynamic part of software and

non software systems. These features include interactions andstate

machines.

Interactions can be of two types:

Sequential (Represented by sequence diagram)

Collaborative (Represented by collaboration diagram)

Interaction Notation:


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Interaction is basically message exchange between two UML

components. The following diagram represents different notations used in

an interaction.

Interaction is used to represent communication among the components of

a system.

State machine Notation:

State machine describes the different states of a component in its life

cycle. The notations are described in the following diagram.


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State machine is used to describe different states of a system component.

The state can be active, idle or any other depending upon the situation.

GROUPING THINGS:

Organizing the UML models are one of the most important aspects of the

design. In UML there is only one element available for grouping and that

is package.

PACKAGE NOTATION:

Package notation is shown below and this is used to wrap the components

of a system.

ANNOTATIONAL THINGS:


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In any diagram explanation of different elemen ts and their functionalities

are very important. So UML has notes notation to support this

requirement.

Note Notation:

This notation is shown below and they are used to provide necessary

information of a system.

RELATIONSHIPS:

A model is not complete unless the relationships between elements are

described properly. The Relationship gives a proper meaning to an UML

model. Following are the different types of relationships available in

UML.

Dependency

Association

Generalization

Extensibility

DEPENDENCY NOTATION:

Dependency is an important aspect in UML elements. It describes the

dependent elements and the direction of dependency.


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Dependency is represented by a dotted arrow as shown below. The arrow

head represents the independent element and the other end the dependent

element.

Dependency is used to represent dependency between two elements of a

system.

ASSOCIATION NOTATION:

Association describes how the elements in an UML diagram are

associated. In simple word it describes how many elements are taking

part in an interaction.

Association is represented by a dotted line with (without) arrows on both

sides. The two ends represent two associated elements as shown below.

The multiplicity is also mentioned at the ends (1, * etc) to show how

many objects are associated.


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Association is used to represent the relationship between two elements of

a system.

GENERALIZATION NOTATION:

Generalization describes the inheritance relationship of the object

oriented world. It is parent and child relationship.

Generalization is represented by an arrow with hollow arrow head as

shown below. One end represents the parent element and the other end

child element.

Generalization is used to describe parent-child relationship of two

elements of a system.

EXTENSIBILITY NOTATION:

All the languages (programming or modeling) have some mechanism to

extend its capabilities like syntax, semantics etc. UML is also having the

following mechanisms to provide extensibility features.

Stereotypes (Represents new elements)

Tagged values (Represents new attributes)

Constraints (Represents the boundaries)


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Extensibility notations are used to enhance the power of the language. It

is basically additional elements used to represent some extra behaviour of

the system. These extra behaviours are not covered by the standard

available notations.

ABSTRACTION RELATIONSHIP

An abstraction relationship is a dependency between model elements that

represents the same concept at different levels of abstraction or fromdifferent viewpoints. You can add abstraction relationships to a model in

several diagrams, including use-case, class, and component diagrams.

ACTIVITY EDGES:

In activity diagrams, an activity edge is a relationship between two

activity nodes that you can use to represent the control flow or object

flow in an activity diagram.

AGGREGATION RELATIONSHIPS:

An aggregation relationship depicts a classifier as a part of, or as

subordinate to, another classifier.


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ASSOCIATION RELATIONSHIPS:

In UML models, an association is a relationship between two classifiers,

such as classes or use cases, that describes the reasons for the relationshipand the rules that govern the relationship.

BINDING RELATIONSHIPS:

In UML models, a binding relationship is a relationship that assigns

values to template parameters and generates a new model element from

the template.

COMMUNICATION PATHS:

In UML modeling, a communication path is a type of association between

nodes in a deployment diagram that shows how the nodes exchange

messages and signals.

COMPOSITION RELATIONSHIPS:

A composition relationship, which was named composition association

relationship in UML 1.4, represents wholepart relationships and is a

form of aggregation. A composition relationship specifies that the

lifetime of the part classifier is dependent on the lifetime of the whole

classifier.

DEPENDENCY RELATIONSHIPS:In UML modeling, a dependency relationship is a relationship in which

changes to one model element (the supplier) impact another model

element (the client). You can use dependency relationships in class


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diagrams, component diagrams, deployment diagrams, and use case

diagrams.

DEPLOYMENT RELATIONSHIPS:In UML modeling, deployment relationships specify that a particular

node type supports the deployment of an artifact type.

DIRECTED ASSOCIATIONRELATIONSHIPS

In UML models, directed association relationships are associations that

are navigable in only one direction.

GENERALIZATION RELATIONSHIPS:

In UML modeling, a generalizat ion relationship is a relationship in which

one model element (the child) is based on another model element (the

parent). Generalization relationships are used in class, component,

deployment, and use case diagrams.

IMPLEMENTATION RELATIONSHIPS:

In UML modeling, an implementation relationship is a specialized type of

realization relationship between a classifier and a provided int erface. The

implementation relationship specifies that the realizing classifier must

conform to the contract that the provided interface specifies.

INCLUDE RELATIONSHIPS:

In UML modeling, an include relationship is a relationship in which one

use case (the base use case) includes the functionality of another use case

(the inclusion use case). The include relationship supports the reuse of

functionality in a use case model.


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MANIFESTATION RELATIONSHIPS:

In UML modeling, a manifestation relationship shows which model

elements, such as components or classes, are manifested in an artifact.The artifact manifests, or includes, a specific implementation for, the

features of one or several physical software components.

REALIZATION RELATIONSHIPS:

In UML modeling, a realization relationship is a relationship between two

model elements, in which one model element (the client) realizes the

behavior that the other model element (the supplier) specifies. Several

clients can realize the behavior of a single supplier. You can use

realization relationships in class diagrams and component diagrams.

USAGE RELATIONSHIPS:

In UML modeling, a usage relationship is a type of dependency

relationship in which one model element (the client) requires another

model element (the supplier) for full implementation or operation.


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COMMON MECHANISMS IN UML

Specifications

textual statement of syntax & semantics

diagrams give view of specification

Adornments

elements in UML - unique graphical notation

adornments - added information about class

Common Divisions

general property vs. specific instance

class vs. object

use case vs. use case instance

UML syntax: underline name of instance

separation of interface & implementation

interface - contract

implementation - concrete realization of contract


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Extensibility Mechanisms

stereotype

allows creation of new kinds of building blocks from existing ones

tagged value

allows creation of new information in specification

constraint

allows addition of new rules & modification of existing rules

\Rules Of UML

specify what model should look like

semantic rules for


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names scopevisibility integrityexecutionCommon properties of modelselided - hide some elements for simplicity incomplete inconsistent rules of UML make it easier to address these problems

ARCHITECTURE OF UML

Any real world system is used by different users. The users can be

developers, testers, business people, analysts and many more. So before

designing a system the architecture is made with different perspectives in

mind. The most important part is to visualize the system from different

viewer.s perspective. The better we understand the better we make the

system.


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UML plays an important role in defining different perspectives of a

system. These perspectives are:

Design

Implementation

Process

Deployment

And the centre is the UseCase view which connects all these four. A Use

case represents the functionality of the system. So the other perspectives

are connected with use case.

Designof a system consists of classes, interfaces and collaboration.

UML provides class diagram, object diagram to support this.

Implementationdefines the components assembled together to make a

complete physical system. UML component diagram is used to support

implementation perspective.

Process defines the flow of the system. So the same elements as used in

Design are also used to support this perspective.

Deploymentrepresents the physical nodes of the system that forms the

hardware. UML deployment diagram is used to support this perspective.

TERMS AND CONCEPTS:


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UML 2.2 has 14 types of diagrams divided into two categories. [10] Seven

diagram types represent structural information, and the other seven

represent general types of behavior, including four that represent different

aspects of interactions. These diagrams can be categorized hierarchically

as shown in the following class diagram:

UML does not restrict UML element types to a certain diagram type. In

general, every UML element may appear on almost all types of diagrams;

this flexibility has been partially restricted in UML 2.0. UML profiles

may define additional diagram types or extend existing diagrams with

additional notations.

In keeping with the tradition of engineering d rawings, a comment or note

explaining usage, constraint, or intent is allowed in a UML diagram.

STRUCTURE DIAGRAMS

Structure diagrams emphasize what things must be in the

system being modeled:

Class diagram: the class diagrams describes the structure of a system

by showing the system's classes, their attributes, and the relationships

among the classes.

Component diagram: depicts how a software system is split up into

components and shows the dependencies among these components.

Composite structure diagram: describes the internal structure of a class

and the collaborations that this structure makes possible.


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Deployment diagram: serves to model the hardware used in systemimplementations, and the execution environments and artifacts

deployed on the hardware.

Object diagram: shows a complete or partial view of the structure of a

modeled system at a specific time.

Package diagram: depicts how a system is split up into logical

groupings by showing the dependencies among these groupings.

Profile diagram: operates at the metamodel level to show stereotypes

as classes with the stereotype, and profiles as

packages with the stereotype. The extension relation

(solid line with closed, filled arrowhead) indicate what metamodel

element a given stereotype is extending.

Since structure diagrams represent the structure they are used extensively

in documenting the architecture of software systems.

BEHAVIOR DIAGRAMS

Behavior diagrams emphasize what must happen in the system being

modeled:

Activity diagram: represents the business and operational step-by-

step workflows of components in a system. An activity diagram

shows the overall flow of control.

State machine diagram: standardized notation to describe many

systems, from computer programs to business processes.

Use case diagram: shows the functionality provided by a system in

terms of actors, their goals represented as use cases, and anydependencies among those use cases.

Since behavior diagrams illustrate the behaviour of a system, th ey are

used extensively to describe the functionality of software systems.


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CLASS DIAGRAM

The class diagram describes the attributes and operations of a class and

also the constraints imposed on the system. The class diagrams are widely

used in the modelling of object oriented systems because they are the

only UML diagrams which can be mapped directly with object oriented

languages.

The class diagram shows a collection of classes, interfaces, associations,

collaborations and constraints. It is also known as a structural diagram.

CONTENTS:

Class diagrams commonly contain the following things

ClassesInterfaces

Collaborations

Dependency,generation and association relationships


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Fig: Class Diagram

conceptual model of the uml

Documents