Common mechanisms

Uml is made similar by the presence of four common

mechanisms that apply consistently throughout the

language. After constructing or developing the

architecture and different views of a software intensive

system, the developer should go for common

mechanisms. We have four types of common

mechanisms. They are…. Specifications

Adornments

Common divisions

Extensibility

Common mechanisms

Adornments Adornments are generally added to an element’s basic notation and are used to visualize details from the element’s specification .They are used to decorate a particular thing to specify some artifacts.

Adornments are classified into two types. They are…..

1. Textual adornments

2. Graphical or symbolic adornments.

Textual adornments

Most adornments are rendered by placing text near the

element. Textual adornments are the strings which delineate the

artifacts of a particular thing or relationship or a diagram. Some

of the common textual adornments are name, role names,

multiplicity, is aggregation or not.

Graphical adornments

Most adornments are rendered by adding a graphic

symbol to the basic elements. These are the adornments used to

specify the artifacts such as relationships, access specifiers etc.

some of the symbolic adornments are..

publicprivate

# protected

note

A note is a special kind of adornment, which is a

graphical symbol for rendering comments or constraints attached

to an element or collection of elements. These are used to specify

things like requirements, observations, reviews and explanations,

in addition to rendering constraints.

A note is rendered in uml using a rectangle with a dog-eared

corner. In uml a note can be rendered in three ways. They are…..

A note may contain some plain text

Put an url inside a note

Simple text

An embedded url

We may link to or embed another document

Extensibility mechanisms

Uml has the capability of extending its vocabulary,

properties, and semantics using one of the mechanisms known as

extensibility mechanisms. This mechanisms permit us to extend the

language in controlled ways.

these mechanisms include…

1. stereo types

2. tagged values

3. constraints

Link to document

constraints

Tagged values

Stereo types

Stereo types

A stereo type extends the vocabulary of the uml, allowing you

to create new kinds of building blocks that are derived from

existing ones but with its own properties, semantics and notation.

in simplest form a stereo type is rendered as a name enclosed by

guillements

define an icon for the stereotype and render that icon

to the right of the name

<<metaclass>>ModelElement

Named stereotype

<<exception>>underflow !

Named stereo type with icon

Render an icon as a basic symbol for the stereo typed item

Tagged values A tagged value extends the properties of a uml building block, allowing to create new information in that element’s specific function.

A tagged value is rendered as a string enclosed by brackets and placed below the name of another element. That string includes a name(tag), a separator(=) and a value( of the tag).

Stereotyped element as icon

Server{processors=3}

Constraints A constraint is a condition which is used to add or modify the existing rules or semantics for a well-formed model we need to have certain constraints established. A constraint is generally rendered as a simple statement or a mathematical equation in a pair of curly braces, and is placed by side of the thing to which it belongs. simple constraint

portfolio

Bank Account

corporation

Gender :{f,m}

person

{secure}

{or}

Constraint across multiple constraints

{self.wife.gender=female andSelf.husband.gender=male}

Formal constraint Using ocl

Comm

on

modeli

ng

techni

ques

based on the common mechanisms we can model the following

modeling comments modeling new building blocks modeling new properties modeling new semantics

Modeling comments

write the comment in the symbol provided and place the note by side of the element to which it refers.

the note can be elided or it can be made visible

if the note is lengthy, then write down the complete description in a document and place a link in the note referring the document

as the model evolves keep those comments that are significant , otherwise remove

Modeling new building blocks Make sure that the thing which we want to model doesn’t have

a graphical representation in uml

After conforming the above select any one of the eleven things

and stereotype it. Stereo typing can be done in two ways .

1. Selecting a stereo type which already exists.

2. Creating our own stereo type.

Specify new properties and semantics for the new thing.

If necessary place a icon for the above stereo type

Modeling new properties Make sure that there is no way to express a value using the

attributes of a class

In the above situation create a new tag and assign it a value

which we want to model <<subsystem>>FieldAccess

{version=2.5Status=checkdin}

<<subsystem>>Billing

{version=3.2Status=checkout

By=edg}

<<subsystem>>AccountsPayable{version=3.2.1

Status=checkedin}

<<subsystem>>WorldCurrency{version=7.5

Status=checedin}

----------------

--------

Modeling new semanticsMake sure there is no way to model the rules of constraints. Write down the constraints and new semantics for the element which we want to model and place adjacent to it If we want to express the constraints in a more precise way use ocl as apart of mentioning the constraints

member 1..* 1 manager

department

person

{subset} <---------

END.