5. Advanced Structural Modeling

Interfaces, Types, and Roles

Sung KimCS6359

Chapter 11 Slide 2

Overview

• Interfaces, types, roles, and realization• Modeling the seams in a system• Making interfaces understandable and

approachable

Sung KimCS6359

Chapter 11 Slide 3

Terms & Concepts• Interface: a collection of operations that

are used to specify a service of a class or a component

• Type: a stereotype of a class used to specify a domain of objects, together with the operations applicable to the object

• Role: the behavior of an entity participating in a particular context.

Sung KimCS6359

Chapter 11 Slide 4

Interfaces

interfaces

wordsmith.dll

IUnknown

IThesaurusISpell

component

Sung KimCS6359

Chapter 11 Slide 5

Interfaces

• Name: simple names, path names• Operations: unlike classes, interfaces do not specify

any structure (no attributes), nor do they specify any implementation (no methods, which provide the implementation of operations).

• Relationships: like a class, an interface may participate in generalization, association, and dependency relationships.

Sung KimCS6359

Chapter 11 Slide 6

Interface vs. Abstract Class

• An abstract class may have attributes, but an interface may not.

• Interfaces span model boundaries. The same interface may be realized by both a class (a logical abstraction) and a component (a physical abstraction that provides a manifestation of the class).

Sung KimCS6359

Chapter 11 Slide 7

Modeling the Seams in a System

• Group those that tend to be tightly coupled relative to other sets of classes and components.

• Refine your grouping by considering the impact of change

• Package logically related sets of cross-boundary operations and signals as interfaces

Sung KimCS6359

Chapter 11 Slide 8

Hints and Tips

• A well-structured interface:– Is simple yet complete. Providing all the operations

necessary yet sufficient to specify a single service.– Is understandable, providing sufficient information.– Is approachable, providing information to guide the user to

its key properties without being overwhelmed by the details of a pile of operations.

Sung KimCS6359

Chapter 11 Slide 9

Summary

• Interfaces, types, & roles• Interface vs. Abstract Class• Modeling the Seams of a System• Well-Structured Interface

5. Advanced Structural Modeling

Packages

Sung KimCS6359

Chapter 12 Slide 11

Overview

• Packages– Visibility– Importing– Exporting– Standard Elements

• Modeling groups of elements

Sung KimCS6359

Chapter 12 Slide 12

Packages

• Package—general-purpose mechanism for organizing elements into groups.

• Names– Simple name—textual string distinguishing one

package from others.– Path name—simple name prefixed by any

enclosing package.

Sung KimCS6359

Chapter 12 Slide 13

Packages Depicted

Business rules

+ OrderForm+ TrackingForm- Order

Client

Sensors::Vision { version = 2.24 }

simple names

extended packages

enclosing package name

package name

path names

Sung KimCS6359

Chapter 12 Slide 14

Owned Elements

• Composite relationship• Destroyed if enclosing package is destroyed

+ OrderForm+ TrackingForm- Order

Client Client

+OrderForm

+TrackingForm

-Order

graphical nesting

textual nesting

visibility

Sung KimCS6359

Chapter 12 Slide 15

Visibility

• You can control the visibility of the elements owned by a package just as you can control the visibility of the attributes and operations owned by a class.

• Packages that are friends to another may see all the elements of that package, no matter what their visibility.

• If an element is visible within a package, it is visible within all packages nested inside the package.

Sung KimCS6359

Chapter 12 Slide 16

Importing & Exporting

• Importing – Grants a one-way permission for elements in one

package to access the elements in another package.

– Dependency with stereotype <<import>>• Exporting

– Public parts of a package.

Sung KimCS6359

Chapter 12 Slide 17

Importing & Exporting Depicted

+Database+LoggingService

Server

+ OrderForm+ TrackingForm- Order

Client

+OrderRules-GUI:Window

Policies <<import>>

+Window+Form#EventHandler

GUI<<import>>

imports

exports

Sung KimCS6359

Chapter 12 Slide 18

Standard Elements• facade—only a view on some other package.• framework—package consisting mainly of patterns.• stub—a package that serves as a proxy for the public

contents of another package.• subsystem—a package representing an independent

part of the system being modeled.• system—a package representing the entire system

being modeled.

Sung KimCS6359

Chapter 12 Slide 19

Modeling Groups of Elements (steps)

• Look for “clumps” of elements that are semantically close to one another.

• Surround “clumps” with a package.• Identify public elements of each package.• Identify import dependencies.

Sung KimCS6359

Chapter 12 Slide 20

Summary

• Packages• Owned Elements• Visibility• Importing & exporting• Standard package elements• Modeling groups of elements

5. Advanced Structural Modeling

Instances, Object Diagrams

Sung KimCS6359

Chapter 12 Slide 22

Overview

• Instances and Objects• Modeling Concrete Instances• Modeling Prototypical Instances• Modeling Object Structures• Forward and Reverse Engineering

Sung KimCS6359

Chapter 12 Slide 23

Instances

• The terms “instance” and “object” are largely synonymous; for most part, they may be used interchangeably.

• Use instances to model concrete or prototypical things that live in the real world.

• Transient: specifies that an instance is created during execution of the enclosing interaction but is destroyed before completion of execution (a standard constraint that applied to objects).

Sung KimCS6359

Chapter 12 Slide 24

Abstractions & Instances

• Instances don’t stand alone: they are almost always tied to an abstraction.

• Instances of:– Classes (objects)– Components, nodes, use cases, and associations

• To indicate an instance, you underline its name.

Sung KimCS6359

Chapter 12 Slide 25

Other Concepts

: keyCode

: Multimedia :: AudioStreamt : Transaction

myCustomer

r : FrameRenderThread

c : Phone [WaitingForAnswer]

myCustomer

id : SSN = “432-89-1738”active = True

agent :

named instance

instance with explicit state

instance with attribute values

active object

multiobject orphan instance

anonymous instance

Sung KimCS6359

Chapter 12 Slide 26

Modeling Concrete Instances (steps)

• Identify the instances necessary and sufficient to model the system.

• Render these objects in the UML as instances; give meaningful names if possible or render it as an anonymous object.

• Expose the stereotypes, tagged values, and attributes.

• Show these instances and their relationships in an object diagram.

Sung KimCS6359

Chapter 12 Slide 27

Modeling Prototypical Instances (steps)

• Identify those prototypical instances necessary and sufficient to model the system.

• Render these objects in the UML as instances; give meaningful names if possible or render it as an anonymous object.

• Expose the properties of each instance.• Show these instances and their relationships in an

interaction diagram or an activity diagram.

Sung KimCS6359

Chapter 12 Slide 28

Object Diagrams• Object diagrams model the instances of things

contained in class diagrams.• Shows a set of objects and their relationships at a

point in time.• Used to model the static design view or static process

view of a system.• Shows a snapshot of the system at a moment in time

and rendering a set of objects, their state, and their relationships.

Sung KimCS6359

Chapter 12 Slide 29

An Object Diagramc : Company

d1 : Department

name = “Sales”

d3 : Department

name = “US Sales”

p : Person

name = “Erin”employeeID = 4362title = “VP of Sales”

d2 : Department

name = “R&D”

: ContactInfomation

address = “1472 Miller St.”

object

link

attribute value

manageranonymous object

Sung KimCS6359

Chapter 12 Slide 30

Modeling Object Structures (steps)

• Identify the mechanism.• For each mechanism, identify classes, interfaces,

and other elements that participate in this collaboration; identify the relationships among these things.

• Consider one scenario that walks through this mechanism. Freeze that scenario at a moment in time and render each object that participate in the mechanism.

• Expose the state and attribute values of each object.• Expose the links among these objects

Sung KimCS6359

Chapter 12 Slide 31

Forward & Reverse Engineering

• Forward engineering an object diagram: possible but limited value.

• Reverse engineering an object diagram: very useful in debugging process.– Choose the target and walk through a scenario– Identify the set of objects that collaborate in

that context.– Expose these object’s states attribute values

and links among these objects.

Sung KimCS6359

Chapter 12 Slide 32

Summary

• Instances• Abstractions & Instances• Modeling Concrete Instances• Modeling Prototypical Instances• Object Diagram• Modeling Object Structures• Forward and Reverse Engineering