L. 5 - 1 © A. H. Levis INCOSE LECTURE 5 OBJECT ORIENTATION FOR ARCHITECTING: A CANDIDATE PROCESS...

L. 5 - 1© A. H. LevisINCOSE

LECTURE 5

OBJECT ORIENTATION FOR ARCHITECTING:

A CANDIDATE PROCESS

LEE W. WAGENHALS

ALEXANDER H. LEVIS

C4ISR ARCHITECTURES AND THEIR IMPLEMENTATION CHALLENGES


OUTLINE

• Introduction - Need for a process

• An OO Process

• Example

• Summary


CONCEPTUAL PROBLEMS

• We have seen that the structured analysis approach requires the functional architecture view composed of the activity model, the data model and the rule model plus a consistent physical architecture view.

• While object orientation offers an alternative to structured analysis, the Uniform Modeling Language does not offer a process for building complete architecture descriptions

• The goal of most OO texts is to develop software, not architectures

• Two new problems arise:

– What is the set of UML diagrams that should be used to represent a complete architecture of an information system or C4ISR?

– Can an Object Oriented process be developed and used to design an architecture?

• As with structured analysis, our requirement is that the combination of information contained in the set of views must be sufficient to yield the specified products and to construct an executable model of the architecture.


OBJECT ORIENTATION APPROACH:ANALYSIS PHASE

Unless the Logical and Physical Architectures are restricted to very high level representations, the Operational Concept is needed to drive both representations and keep them compatible

LOGICAL ARCHITECTURE

VIEW

OPERATIONALCONCEPT

PHYSICALARCHITECTURE

VIEW

MISSION

USE CASE ANALYSIS

ORGANIZATIONMODEL


LOGICAL ARCHITECTURE VIEW

LOGICAL ARCHITECTURE

VIEWIS

BEHAVIORAL DIAGRAMSincluding

Rule Model

CLASS DIAGRAMDICTIONARY

DATA


A DETAILED VIEW

ORGANIZATIONMODEL

OPERATIONALCONCEPT

LOGICALARCHITECTURE

VIEW

PHYSICALARCHITECTURE VIEW

EXECUTABLEMODEL MOPs, MOEs

TECHNICALARCHITECTURE VIEW

BEHAVIORAL DIAGRAMS (inc.Rule Model)

CLASS DIAGRAM

DATA DICT.

MISSION

EVALUATIONPHASE


A REQUIREMENTS VIEW

ORGANIZATIONMODEL

OPERATIONALCONCEPT

LOGICALARCHITECTURE

VIEW

PHYSICALARCHITECTURE VIEW

EXECUTABLEMODEL MOPs, MOEs

TECHNICALARCHITECTURE VIEW

BEHAVIORAL DIAGRAMS (inc.Rule Model)

CLASS DIAGRAM

DATA DICT.

MISSION

EVALUATIONPHASE


A FIVE STAGE PROCESS

• A five-stage process has been developed that uses the Unified Modeling Language and the associated diagrams to design the Operational and Systems Architecture views

• The architecture information contained in the diagrams is then mapped into the C4ISR products

• Not all C4ISR products are derivable from the OO architecture design (nor are they derivable from the structured analysis approach)

• A high level description of the process is shown on the next viewgraph


A FIVE STAGE PROCESS

GATHER DOMAIN

INFORMATION

DEVELOP CLASS

DIAGRAMS

DEVELOP BEHAVIORAL DIAGRAMS &RULE MODEL

DEPICTORGANIZATIONAL

STRUCTURE

DESCRIBE PHYSICAL ARCHITECTURE

DEVELOP DEPLOYMENT

DIAGRAM

DEVELOP COMPONENT DIAGRAMS SYNTHESIS

EXECUTABLE MODEL

STAGE 0 STAGE 1 STAGE 2 STAGE 3 STAGE 4

LOGICAL

PHYSICAL

MAINTAIN INTEGRATED DICTIONARY

ALL0 FORMULATE

OPERATIONAL CONCEPT

DEVELOP USE CASES AND

THEIRDIAGRAMS

1

1

0

2

2

3

03 4

ENSURECONCORDANCE


A FIVE-STAGE PROCESS

STAGE 0: Problem Definition and Collection of Domain Information

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

STAGE 1: Operational Concept and Requirements; Use Cases and Diagrams

STAGE 2: Class Diagrams, Behavioral Diagrams, Rule Model, Concordance

STAGE 3: Physical Nodes and Links; Component Diagrams, allocation to Physical Nodes and Links (Deployment Diagram)

STAGE 4: Synthesis (executable model)

All STAGES Maintain Integrated Dictionary


STAGE 0

• Define Problem and Identify Domain

• Gather Domain Information

• Describe Physical Architecture

– Legacy systems and their characteristics

– Planned systems

– Future systems and alternatives

Note: Legacy systems and their interfaces can be thought as physical design constraints on the architecture


IDEF0 MODEL OF PROCESS

Purpose: to describe a process for developing an information system architecture using Object Orientation

View Point: System Architect

Design Information

System Architecture

A0

Domain Knowledge

Object Orientation &UML Guidelines

Information System Architecture


OVERALL PROCESS

DomainKnowledge

Information SystemArchitecture

Object OrientationUML Guidelines

Do STAGE 1

A1

DoSTAGE 2

A2

DoSTAGE 3

A3

Maintain Integrated Dictionary

A4

Operational Concept and Use Cases

UML Based Logical Architecture

Physical Architecture

IntegratedDictionary

UML Based


STAGE 1

Once the basic information has been assembled in Stage 0, the process starts by defining the Operational Concept that implies or includes organizations and actions or tasks. This is expressed as the operational concept graphic with a textual description

The operational concept is expanded by developing Use Cases.

These describe scenarios between users and the system for which the architecture is being developed. A scenario is a sequence of interactions between a user and a system.

There is no specified format. Textual descriptions listing interactions with actor or system (noun), the next activity (verb), and result (noun) are used. Other formats include a table listing, for each interaction, Actor, System, Pre-condition and Post-condition.


STAGE 1 ESTABLISH REQUIREMENTS

Domain Knowledge

Object Orientation/UML Guidelines


Formulate Operational

ConceptA11

Develop Use Cases

A13

Determine Organizational

FeaturesA12

Use Cases with Diagrams

Operational Concept

Organizations


STAGE 2

• Once the required operation of the system has been defined, the logical architecture for carrying out the use cases is designed.

• The architect decides what activities and information flows will accomplish the operational concept as defined by each use case, allocates those activities to Classes, determines the attributes that each class needs to carry out its activities (operations), and develops the rules for each operation. Concordance is crucial throughout this process which is iterative rather than sequential


DEVELOP LOGICAL ARCHITECTURE

UML Based Logical ArchitectureDomain

Knowledge



Develop Class

Diagram

A21

Develop Behavioral Diagrams

A22

DevelopRule Model

A23

Ensure Concor-dance

A24

Object Class

Collaborations, activities, and links

Object Class Diagram

Rule Model

Behavioral Diagrams

Corrections


STAGE 2 (continued)

• It is the architect’s choice as to which model to begin with

– The architect may start with a candidate set of classes and then describe the behavior using the behavioral diagrams (activity diagram or sequence diagram)

– Alternatively the architect can start with behavioral diagrams, e.g. activity diagram, to determine how the use case will be carried out. Once the activity diagram is created, the activities can be allocated to objects and the activity diagram enhanced with swim lanes to show the interaction between classes.

– Regardless of the starting point, the architect will quickly be working with a set of diagrams all showing different aspects of how the architecture will carry out each use case.


CONCORDANCE

• As with structured analysis, maintaining concordance between the model views is crucial

• Each type of behavioral diagram reflects the design of the same architecture. Each highlights a different aspect of that behavior.

• Activity Diagrams reflect the processes used to carry out the use cases. They describe the sequencing of activities. Decomposition of activities is supported. The activities will be carried out by the operations of the classes. Thus it is recommended that the names of the activities and the operations be the same.

• Once activities have been allocated to classes, then the flow of information between them can be determined from the activity diagram and must match the association paths on the collaboration diagram and the flows on the sequence diagram.


CONCORDANCE

Activity A1

Activity O2

Activity O3

Activity A4

Object 1 Object 2

Object 1

Object 2

Operation O3

Operation O2

Object 1 Object 2

opeationO2()

operationO3()

activityA4()

2.operationO3()

1.operationO2()

3. activityA4()

Activity Diagram

Collaboration Diagram

Class 1

Class 2

Operation O3

Operation O2

Class 3

Class Diagram

Sequence Diagram


CONCORDANCE

• The links on the collaboration diagram are labeled with the messages that carry the information between the two objects.

– UML message format

» predecessor guard-condition sequence expression return value:=message_name (argument list).

» e.g., 1.1, [x<y]*[I=1..n] s:=drawSegment(n)

» Not all elements of the message need be used

– Message labels on collaboration diagrams and on sequence diagrams for the same event should match


CONCORDANCE

• The Class diagram is a composite structure of the collaboration diagrams.

– The associations on the Class diagram must represent one or more links on the set of collaboration diagrams.

» If there is a link on a collaboration diagram and no corresponding association on the class diagram, an error exists.

» If an association exists and there is no corresponding link on any collaboration diagram, an error may exist.

– Not that the association names are chosen to enhance overall understanding and they do not have to be the same as the message label of the links.


STAGE 3

Physical ArchitectureDomain Knowledge



UML Based Logical Architecture

Develop Physical

ArchitectureA31

Develop Component Diagrams

A32

Develop Deployment

Diagram

A33

System Nodes and Links

Components

UML Based


STAGE 3

• In completing the physical architectures, use the principles that applied to structured analysis

– Define system nodes and links using the operational concept and organizational features as a guide

• Objects are grouped into components to create component diagrams

• Components are allocated to system nodes in the physical architecture

– All logical associations must be instantiated with communications links


EXAMPLE

• A simple example of an Automatic Teller Machine can be used to illustrate the process

• The operational concept is that we will create an architecture for a system that uses ATMs to allow bank customers to withdraw cash from their bank accounts at any time.

– Two options will be available: a Fast Cash option that provides a set amount of cash, and a regular withdrawal where the customer can specify the amount of cash to be withdrawn

– Customers use an ATM card issued by the bank to initiate the process. They must use a PIN.


USE CASE EXAMPLE

• Use Case: Withdrawal

• Actors: Customer, Bank

• Type: Primary

• Description: A customer arrives at an ATM with ATM Card to withdraw cash. The customer inserts the card into the ATM. The ATM prompts the customer to enter PIN. The customer enters PIN and the system authorizes the withdrawal. The customer enters the amount to be withdrawn. The ATM dispenses the cash and provides a receipt. The ATM sends transaction records to the Bank to update the account balance. On completion, the customer leaves with the cash and receipt


ATM

Withdrawal

FastCash Withdrawal

Use Case Diagram of ATM

User

SSNFirstNameLastNameAddress

InsertCard()TypePIN()

CollectReceipt()CollectCard()

Select()EnterAmount()CollectCash()

Bank

BankCodeName

ValidateUser()AuthorizeTransaction()

STAGE 1

Activity Diagram of Withdrawal Use Case

Insert Card

Type PIN

Request PIN

Request

Receive Validation

Display Options

Select Options

Enter Amount

Request Amount

Compare Cash Limit

Read PIN

Validate User

Request Authorization

Receive Authorization

Collect Cash

Dispense Cash

Print Receipt and Eject Card

Authorize Transaction

Collected Receipt and Card

[ Transaction Authorized ][ Transaction NotAuthorized ]

[ User Validated ]

[ User NotValidated ]

[ Amount < CashLimit ]

[ Amount > CashLimit ]

Withdraw FastCashWithdraw

Card

Account

ATM

1..*

1..*

1..*

1..*

transfer information

SessionBank

1..*1 1..*1

manage

1..*

1

1..*

1

maintain

1..*

1

1..*

1

validate

Transaction

1..*

1

1..*

1

1..*

1

1..*

1

authorize

User

(from Use Case View)1..*

1

1..*

1own

1..*

1

1..*

1

has

1..*

1..*

1..*

1..*use

1..*

1

1..*

1

participate

1..*

1..*

1..*

1..*

perform

INITIAL CLASS DIAGRAM OF ATM

1

1..*

ALLOCATE ACTIVITIES TO CLASSES

USER

BANK

ATM

SESSION

TRANSACTION

Insert Card

Type PIN

Request PIN

Request Validation

Receive Validation

Display Options

Select Options

Enter Amount

Request Amount

Compare Cash Limit

Read PIN

Validate User



Collect Cash

Dispense Cash



Collecting Receipt and

[ Amount < CashLimit ]

[ Transaction Authorized ]

[ Transaction NotAuthorized ]

[ Amount > CashLimit ]

[ User Validated ]


Activity Diagram of Withdrawal Use Case with Swim

Lanes

• Activities are allocated to Objects

• Activities become operations

• The connectors in the Activity Diagram correspond to Associations in Class Diagram and links in Collaboration and Sequence Diagrams

• Messages labels can be added

Insert Card

Type PIN

Enter Amount

Select Options

Collect Cash

Collecting Receipt and Card

User

Request Validation

Receive Validation

Activity Diagram of Withdraw Use Case

Session

Request Amount

Select Withdraw

Compare Cash Limit



Withdraw

Read PIN

Request PIN

Display Options

Dispense Cash


ATM

Validate User


Bank

[ Amount < Limit ]

[ Amount > Limit ]

[ User Validated ]


CardID

PIN

(CardID, PIN)

(CardID, PIN)

(CardID, Validation)

(TransactionID, CardID, Amount)

(TransactionID, Approval)

(Card, Receipt)

SignalType=PINRequest

[ Transaction Authorized ]

[ Transaction NotAuthorized ]SignaType=CollectCash

Cash Collected

SignalType=Options

SignalType=RequestAmount

Amount

NewSwimlane10 : BankNewSwimlane9 : ATMNewSwimlane8 : WithdrawNewSwimlane7 : SessionNewSwimlane6 : User


ADDING OPERATIONS AND ATTRIBUTES

• Operations derived from Activity Model

• Attributes defined as needed based on rule model

Transaction

TransactionIDDateTime

ManageLog()RequestAuthorization()ReceiveAuthorization()ApproveWithdraw()

Withdrawal

AmountCashLimit

RequestAmount()

CompareCashLimit()

FastCashWithdrawal

FastCastAmount


RULE MODEL

• Based on the Activity Diagram

• Developed in the same manner as for Structured Analysis

– Use Structure English, Decision Tables and Trees

• Rules apply only to the lowest level of decomposition in the Activity Diagram

• Ensure each Clause of rule matches either:

– Attribute of Object

– Message sent to the object (calling the activity/operation)

– Message or return from the object’s activity/operation

• As with data modeling in structured analysis, domains must be defined for each attribute and message

Sequence Diagram of FastCash Withdraw Use Case

: User : Bank : FastCashWithdraw : Session : ATM

InsertCard()

DisplayOptions()

Select (FastCashWithdraw)

DispenseCash(FastCashAmount)

CollectCash()

DisplayOptions()

Select (Quit)

EjectCard()

PrintReceipt()

RequestPIN()

TypePIN()

ActivateSession(CardNumber, PIN)

RequestValidation(CardNumber, PIN)

ConfirmValidation()

Activate(FastCashWithdraw)

RequestAuthorization(TransactionID, CardNumber, FastCashAmount)

AuthorizeTransaction(TransactionID)

ApproveWithdraw(FastCashAmount)

ValidateUser(CardNumber)


SEQUENCE DIAGRAM

• Shows the sequence for messages between objects for the use case

• Must match the Activity Diagram in structure

• Emphasis is on the messages rather than the activities

• Messages must match the conditions or actions of the rule model for each activity operation

Collaboration Diagram of Withdrawal Use Case

Must match the Sequence Diagram (and the Activity Diagram)

: User

: ATM

: Bank

: Session

: Withdraw

13: CompareCashLimit()

1: InsertCard()3: TypePIN()

9: Select (Withdraw)18: CollectCash()20: Select (Quit)

2: RequestPIN()8: DisplayOptions()

17: DispenseCash(Amount)19: DisplayOptions()

21: EjectCard()22: PrintReceipt()

4: ActivateSession(CardNumber, PIN)

7: ConfirmValidation()

10: Activate (Withdraw)16: ApproveWithdraw(Amount)

5: RequestValidation(CardNumber, PIN)

6: ValidateUser(CardNumber)

11: RequestAmount()

12: EnterAmount()

14: RequestAuthorization(TransactionID,CardNumber,Amount)

15: AuthorizeTransaction(TransactionID)

Class Diagram of ATM

Class Diagram is a composite overlay of the collaboration diagrams

Withdraw FastCashWithdraw

Card

Account

ATM

1..*1..*

Session

1..*

11

has

Bank

1..*1 1..*1

manage

1..*

1

1..*

1

maintain

1..*

1

1..*

1

validate

Transaction

1..*

1

1..*

1

1..*

1

1..*

1

authorize

User

1..*

1

1..*

1own

1..*

1

1..*

1

has

1..*

1..*

1..*

1..*use

1..*1..*

1..*

1..*

1..*

1..*

perform

activate

1

1 1..*

Withdraw

AmountCashLimit

RequestAmount()CompareCashLimit()

FastCashWithdraw

FastCashAmount

Card

CardNumberPIN

Account

AccountNumberTypeBalance

Withdraw()Open()Close()

ATM

ATMIDOwnerBank

DisplayOptions()ReadCard()DispenseCash()PrintReceipt()EjectCard()RequestPIN()ReadPIN()ActivateSession()Activate()

1..*

1..*

1..*

1..*

trasnfer information

Session

SessionID

RequestValidation()ReceiveValidation()ConfirmValidation()

1..*

1

1..*

1

has

Bank

BankCodeName

ValidateUser()AuthorizeTransaction()

(from Use Case View)

1..*

1

1..*

1

manage

1..*

1

1..*

1

maintain

1..*

1

1..*

1

validate

Transaction

TransactionIDDateTime

ManageLog()RequestAuthorization()ReceiveAuthorization()ApproveWithdraw()

1..*

1

1..*

1

1..*

1

1..*

1

authorize

User

SSNFirstNameLastName

Address

InsertCard()TypePIN()

CollectReceipt()CollectCard()

Select()EnterAmount()CollectCash()

(from Use Case View)1..*

1

1..*

1

own

1..*

1

1..*

1

has

1..*

1..*

1..*

1..*use

1..*

1

1..*

1

1..*

1..*

1..*

1..*

perform

FULL CLASS DIAGRAM


STATE CHARTS

• State Charts (or State Transition Diagrams) should be created for each Object Class

– Note that this is different from our approach with Structure Analysis where Dynamics Models are produced for the entire system

• Same rules apply and concordance must be maintained

– States are consistent with other behavioral diagrams

– Transitions are annotated with events (message arrivals), guard functions (from rule model) and actions (that can be operations and match rule model)

– Path from initial state to final state must match the threads on the activity diagram and match the life-lines on the sequence diagram

STATE CHART FOR ATM OBJECT CLASS

Waiting for Card

Initial State

Waiting for PIN

Card Inserted / RequestPIN()

Displaying Options

Waiting for Authorization

Dispensing Cash

Printing Reciept and Returning Card

User Collects Money / PrintReceipt(), EjectCard()

Waiting for Validation

PIN Entered / ActivateSession()

User Select Transaction / Activate(Transaction)

Validation Received[ User Validated ] / DisplayOptions()

Validation Received[ User NotValidated ] / PrintReceipt(), EjectCard()

Authorization Received[ Transaction Authorized ] / DispenseCash()Authorization Received

[ Transaction NotAuthorized OR Amount > Limit ]

User collects card and receipt


SUMMARY

• We have demonstrated a candidate process by which the Object-Oriented paradigm can be applied to the architecture specification problem

– Understanding and maintaining Concordance and the Integrated Dictionary is absolutely necessary

• Tools:

– Rational Rose supports the creation of UML diagrams, but it does not support concordance in the manner needed for architecture development

– Ptech’s Framework™ supports object orientation and the creation of the UML diagrams; current DOD funded effort for the automatic generation of the Colored Petri net based executable model in progress.

L. 5 - 1 © A. H. Levis INCOSE LECTURE 5 OBJECT ORIENTATION FOR ARCHITECTING: A CANDIDATE PROCESS...

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Transcript of L. 5 - 1 © A. H. Levis INCOSE LECTURE 5 OBJECT ORIENTATION FOR ARCHITECTING: A CANDIDATE PROCESS...