capsule structure

7/29/2019 Capsule Structure

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Developing Real-Time Software with

Rational Rose RealTimeVersion 2001A.04.00

Module 10: Capsule Structure: Ports, Protocols,

and Sub-capsules


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Developing Real-time Software With Rational Rose RealTime, v2001A.04.00

Copyright 2001 Rational Software, all rights reserved

Ports, Protocols, and Components Topics

Capsule Interfaces

Ports

Protocol Classes

Capsule Structure


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The Encapsulation Shell

Abstracts the functionality of the capsule

Keeps changes within the capsule fromaffecting elements that interact with it

Protects objects it contains


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Capsule Interfaces

A capsules interface is completely defined

by its ports.

Ports


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Capsule Interfaces

Ports

Protocol Classes

Capsule Structure


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Ports

Capsules communicate by sending and receiving

messages through ports A port can only send and receive specific sets of

messages

Defined by a protocol class

Stimulus

message

Response

messages


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Ports (cont.)

Ports are interface elements between a

capsules structure and behavior Ports have a composition relationship with

the capsule they serve

Ports are created and destroyed along with thecapsule that owns them


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Ports: Port Compatibility

Only ports with compatible protocols can

communicate with each other Two ports are compatible if they are of the

same protocol or subclass

In order for two ports to be connected, theymust be opposite in conjugation

Base port

Conjugated port


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Ports: Port Termination

End ports: terminate

connectors; delivermessages from acapsules structureto capsulesbehavior, and viceversa

Relay ports: relaymessages to/from asubcapsule to acapsule outside itscontainer

Relay PortContained

Capsule RoleContaining

Capsule

Boundary

End Port


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Ports: Wired vs. Unwired Ports (Java)

Wired ports: use

connectors to set upmessage channelsExplicit visible

associations

Unwired ports: usename binding to setup message channelsNo connectors used

Dynamic connectionsMechanism used with

Connexis

Unwired port Wired ports


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Ports: Port Visibility (Java)

Public ports: define a

capsules externalinterfaceAppear on capsules

boundary in a structurediagram

Use UML + in the name

Protected ports: connecta capsule to itssubcapsules Not accessible from outside

a capsule, unless published

Use UML # in the nameProtected port

Public port


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Capsule Interfaces

Ports

Protocol Classes

Capsule Structure


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Protocol Class

Specifies which messages can be sent to and

received from a port A message is defined by a named signal and any

optional data

Protocol

Class

DeviceControl

isOn (void)

isOff (void)

turnOn (void)

turnOff (void)


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Protocol Classes: Contractual Interaction Patterns

Protocol classes act as a contract

between capsules, specifying whatmessages can be sent between them

Example: operator-assisted call

time

call

ack

number

ringBack

Caller Operator

connected


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Protocol Roles

A protocol class specifies the communication

patterns between capsules, viewed from either endof the connection.

The protocol role represents only a single view(base orconjugate), specifying which messages

can be sent to and received by that specific porttype

The protocol role of the port determines whichsignals are incoming and outgoing

Two ports must realize compatible protocols topermit a connector to be established betweenthem


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Protocol Roles: Example

Aprotocol role specifies the protocol from

the perspective of one partyOne protocol definition

defines two roles:

Base Conjugate

significant sequence

caller operator

call

ack

number

ringBack

connected

ProtocolRoleB

ack (void)

ringBack (void)

connected (void)

call (void)

number (void)

ProtocolRoleA

call (void)

number (void)

ack (void)

ringBack (void)

connected (void)

Base Protocol Role Conjugate Protocol Role


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Defining Protocols

Protocols capture the interactions related to each

role a capsule plays in its collaborations

Capsules that playsimilar roles may reuseprotocol definitions

Protocols should not beoverloaded and shouldhave a clear purpose: Capture a complete

message dialog betweencollaborating capsules


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Capsule Interfaces

Ports

Protocol Classes

Capsule Structure


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Capsule Structure

Capsules contain

componentelements:

Subcapsules

Passive classesPorts

Connectors


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Structure Diagram

A specialized form of the collaboration

diagram Specifies the capsule's interface and its

internal composition

Ports

Connector

Capsule

Subcapsule


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Connectors

Objects that show key communication

relationships between capsulesConnect ports that play complementary roles in

the protocol they are associated with

Can connect ports associated with differentprotocols if the ports are conjugate and theprotocols have compatible in- and out-signals.

Connector


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Collaboration Diagram to Structure Diagram

A structure diagram is a more specialized

form of collaboration diagram.

Collaboration Diagram

Structure Diagram


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Showing Structure in a Class Diagram

A class diagram provides more detailed

system decomposition

Structure Diagram

TheSystem

Client

+ / link : Link

Server

+ / link : Link~

Link

response (void)

command (void)

+ / link

+ / link~

/ server/ client

Class Diagram

/ client: Client

/ server: Server

+ / link

: Link

+ / link

: Link~


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Review: Designing Ports and Protocols

Why are ports used to connect capsules?

Why must connected end ports beopposite in conjugation?

Why use a class diagram instead of a

structure diagram?

L T D i


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Low Temp Dyeing

Controller Tank

fill

drain

level

start

Operator

done

The Dying System

Dyeing

Level

Filling EmptyDraining

Time

capsule structure

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