C4ISR ARCHITECTURES AND THEIR IMPLEMENTATION CHALLENGES LECTURE 5 OBJECT ORIENTATION FOR ARCHITECTING: A CANDIDATE PROCESS LEE W. WAGENHALS ALEXANDER H. LEVIS 1

OUTLINE Introduction - Need for a process An OO Process Example Summary 2

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. 4

OBJECT ORIENTATION APPROACH: ANALYSIS PHASE MISSION OPERATIONAL CONCEPT USE CASE ANALYSIS PHYSICAL ARCHITECTURE VIEW ORGANIZATION MODEL LOGICAL ARCHITECTURE VIEW 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 IS BEHAVIORAL DIAGRAMS including Rule Model CLASS DIAGRAM D I C T O N A R Y

A DETAILED VIEW MISSION OPERATIONAL CONCEPT TECHNICAL ARCHITECTURE VIEW ORGANIZATION MODEL LOGICAL ARCHITECTURE VIEW PHYSICAL ARCHITECTURE VIEW BEHAVIORAL DIAGRAMS (inc.Rule Model) CLASS DIAGRAM DATA DICT. EVALUATION PHASE EXECUTABLE MODEL MOPs, MOEs

A REQUIREMENTS VIEW MISSION OPERATIONAL CONCEPT TECHNICAL ARCHITECTURE VIEW ORGANIZATION MODEL LOGICAL ARCHITECTURE VIEW PHYSICAL ARCHITECTURE VIEW BEHAVIORAL DIAGRAMS (inc.Rule Model) CLASS DIAGRAM DATA DICT. EVALUATION PHASE EXECUTABLE MODEL MOPs, MOEs

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 DEVELOP CLASS DIAGRAMS 2 MAINTAIN INTEGRATED DICTIONARY ALL GATHER DOMAIN INFORMATION FORMULATE OPERATIONAL CONCEPT 1 DEVELOP USE CASES AND THEIR DIAGRAMS 1 DEVELOP BEHAVIORAL DIAGRAMS & RULE MODEL 2 ENSURE CONCORDANCE DEPICT ORGANIZATIONAL STRUCTURE LOGICAL DEVELOP COMPONENT DIAGRAMS 3 PHYSICAL SYNTHESIS EXECUTABLE MODEL 4 DEVELOP DEPLOYMENT DIAGRAM 3 DESCRIBE PHYSICAL ARCHITECTURE STAGE 0 STAGE 1 STAGE 2 STAGE 3 STAGE 4

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 Design Information System Architecture A0 Domain Knowledge Object Orientation & UML Guidelines Information System Purpose: to describe a process for developing an information system architecture using Object Orientation View Point: System Architect

OVERALL PROCESS Object Orientation UML Guidelines Operational Concept Domain Knowledge Information System Architecture Object Orientation UML Guidelines Do STAGE 1 A1 STAGE 2 A2 STAGE 3 A3 Maintain Integrated Dictionary A4 Operational Concept and Use Cases UML Based Logical Architecture Physical

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 Object Orientation/UML Guidelines Operational Concept Formulate Domain Knowledge Operational Operational Concept Concept and Use Cases A11 Organizations Determine Organizational Use Cases with Diagrams Features A12 Develop Use Cases A13

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 Object Orientation/UML Guidelines Object Class Diagram Operational Concept Develop UML Based and Use Cases Class Logical Architecture Domain Knowledge Diagram Behavioral A21 Diagrams Object Class Develop Behavioral Collaborations, Diagrams activities, A22 and links Rule Model Develop Rule Model A23 Ensure Corrections Concor- dance A24

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 Diagram Collaboration Diagram Class Diagram Object 1 Object 2 Object 1 1.operationO2() Activity 2.operationO3() A1 Operation O2 Activity O2 Object 2 3. activityA4() Activity O3  Operation O3 Activity Class 1 Class 2 Operation O3 Operation O2 Class 3 Class Diagram A4 Sequence Diagram Object 1 Object 2 opeationO2() operationO3() activityA4()

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 Architecture Domain Knowledge Object Orientation/UML Guidelines Operational Concept and Use Cases UML Based Logical Architecture Develop A31 Component Diagrams A32 Deployment Diagram A33 System Nodes and Links Components

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

STAGE 1 Use Case Diagram of ATM ATM Withdrawal User Bank SSN FirstName LastName Address InsertCard() TypePIN() CollectReceipt() CollectCard() Select() EnterAmount() CollectCash() Bank BankCode Name ValidateUser() AuthorizeTransaction() FastCash Withdrawal

Activity Diagram of Withdrawal Use Case Request Display Options Authorization Insert Card Authorize Select Options Transaction Request PIN Receive Request Type PIN Authorization Amount [ Transaction NotAuthorized ] [ Transaction Authorized ] Enter Amount Read PIN Dispense Cash Request Compare Cash Limit Collect Cash [ Amount < CashLimit ] Validate User Print Receipt [ Amount > CashLimit ] and Eject Card Receive Validation [ User Validated ] [ User NotValidated ] Collected Receipt and Card NewState2

INITIAL CLASS DIAGRAM OF ATM transfer information use 1..* 1..* 1..* 1..* 1 1 1 1 own 1 1 User Card (from Use Case View) 1 has 1..* 1..* participate perform 1..* 1..* 1 1 1..* 1..* 1 1 manage 1..* 1..* Account 1 1 validate 1..* 1..* 1 1 Session 1..* 1..* Bank authorize 1 1 maintain 1..* 1..* 1..* 1..* 1..* 1..* 1..* 1..* ATM 1..* Transaction 1..* 1..* 1..* 1..* Withdraw FastCashWithdraw

ALLOCATE ACTIVITIES TO CLASSES USER BANK ATM SESSION TRANSACTION

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

ADDING OPERATIONS AND ATTRIBUTES Transaction TransactionID Date Time ManageLog() RequestAuthorization() ReceiveAuthorization() ApproveWithdraw() Withdrawal Amount CashLimit RequestAmount() CompareCashLimit() FastCashWithdrawal FastCastAmount Operations derived from Activity Model Attributes defined as needed based on rule model

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() 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 6: ValidateUser(CardNumber) 5: RequestValidation(CardNumber, PIN) 2: RequestPIN() Must match the Sequence Diagram (and the Activity Diagram) 8: DisplayOptions() 17: DispenseCash(Amount) 19: DisplayOptions() : User 21: EjectCard() 22: PrintReceipt() : Bank 1: InsertCard() 3: TypePIN() 9: Select (Withdraw) 18: CollectCash() 20: Select (Quit) 4: ActivateSession(CardNumber, PIN) : ATM : Session 7: ConfirmValidation() 11: RequestAmount() 12: EnterAmount() 16: ApproveWithdraw(Amount) 10: Activate (Withdraw) 13: CompareCashLimit() 15: AuthorizeTransaction(TransactionID) : 14: RequestAuthorization(TransactionID,CardNumber,Amount) Withdraw

Class Diagram of ATM use 1..* 1..* 1..* 1..* 1 1 own 1 1 User Card has 1..* 1..* perform 1..* 1..* 1 1 1 1 manage 1..* 1..* Account 1 validate 1..* 1..* 1 1 1 1..* 1..* Session Bank authorize 1 1 1..* maintain 1 1..* 1..* 1..* 1..* 1..* 1..* 1 1..* 1..* activate ATM 1..* Transaction 1..* 1..* Class Diagram is a composite overlay of the collaboration diagrams 1..* 1..* 1 1 Withdraw FastCashWithdraw has

FULL CLASS DIAGRAM Withdraw Card Account ATM 1..* Session 1 1..* 1..* Amount CashLimit RequestAmount() CompareCashLimit() FastCashWithdraw FastCashAmount Card CardNumber PIN Account AccountNumber Type Balance Withdraw() Open() Close() ATM ATMID OwnerBank DisplayOptions() ReadCard() DispenseCash() PrintReceipt() EjectCard() RequestPIN() ReadPIN() ActivateSession() Activate() 1..* trasnfer information Session SessionID RequestValidation() ReceiveValidation() ConfirmValidation() 1 has Bank BankCode Name ValidateUser() AuthorizeTransaction() (from Use Case View) manage maintain FULL CLASS DIAGRAM use 1..* 1..* 1 1 1 1 1..* 1..* own User 1 1 1..* 1..* (from Use Case View) SSN FirstName has LastName Address InsertCard() TypePIN() CollectReceipt() CollectCard() perform Select() EnterAmount() CollectCash() 1..* 1..* 1 1 1 1 validate 1..* 1..* authorize 1..* 1..* 1 1 1..* 1..* 1..* 1..* 1..* 1..* Transaction TransactionID Date Time 1..* 1..* ManageLog() RequestAuthorization() ReceiveAuthorization() ApproveWithdraw()

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 Initial State Waiting for Card Card Inserted / RequestPIN() Waiting for PIN Validation Received[ User NotValidated ] / PrintReceipt(), EjectCard() PIN Entered / ActivateSession() Waiting for Validation Validation Received[ User Validated ] / DisplayOptions() Displaying User collects card and receipt Options User Select Transaction / Activate(Transaction) Waiting for Authorization Authorization Received[ Transaction Authorized ] / DispenseCash() Authorization Received [ Transaction NotAuthorized OR Amount > Limit ] Dispensing Cash User Collects Money / PrintReceipt(), EjectCard() Printing Reciept and Returning Card

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.