2
Senior Principal Product Manager
Application Development Tools
Oracle Corporation
Based on presentation by Nick Kavantzas, Oracle, editor CDL spec, W3C Choreography WG

3
y
y
y
y
y

4
y Specify a declarative language that describes collaborations of Web Services participants by defining their externally observable behavior as part of an inter-organizational transaction y Based on a formal model
– pi-calculus variation

5
Sample Purchase Order
Purchase Order Request
Business
“ A ” Purchase Order Acknowledgement
Business
“ B ”
Purchase Order Response

6
Public Process
Business A
Send
PO
PO Request
Receive PO
Ack
PO Acknowledgement
Receive PO
Response
PO Response
Business B
Receive
PO
Send
PO Ack
Send PO
Response
Choreography – The observable public exchange of messages

7
From ERP
To ERP
Private Process
Business A BPEL Workflow
Transform
Send
PO
Transform
PO Request
Receive PO
Ack
PO Acknowledgement
Receive PO
Response
PO Response
Orchestration – A private executable business process

8
Generate BPEL
Template
Business Analyst Tool
Business
A
Business
B
Generate BPEL
Template
Business A BPEL Workflow
Transform
Send
PO
Business B BPEL Workflow
Receive
PO
Transform
PO Request
Transform
Receive PO
Ack
PO Acknowledgement
Send PO Ack
Receive PO
Response
PO Response
Receive PO
Response
Two BPEL workflow templates reflecting a business agreement
Transform

y
–
Loosely-coupled, stateless
–
Exchange of type checking information
9
HTTP , BEEP,IIOP, JMS, SMTP

Business Collaboration Language: Web Services Integration
10
HTTP , BEEP,IIOP, JMS, SMTP

11
y Web Services participants interact and align their shared information
–
–
Synchronized document exchanges (state)
Progress is guarded by commonly defined ordering rules y Set of Interactions are combined to form a behavioral unit (choreography)
–
Enables re-usability in different business contexts

12 y Information Typing
–
–
Document Type
Token
–
Locator y Identifying & Coupling of WS participants
–
–
Role
Relationship y Information driven collaboration
–
Channel
–
–
–
–
State
Activity
Reaction (a.k.a. Rule)
Choreography

13 y The example is a multi-participant choreography y Illustrates a simple purchase sequence y It involves four participants, Roles
–
Buyer, Seller, Credit Checking Service, and Inventory
Service y Main choreography involves 3 relationships
–
Buyer-Seller
–
–
Seller-Credit Checking Service
Seller-Inventory Service

14 y The Buyer initiates an interact with the Seller to align the Purchase Order y The Seller, when the Purchase Order is available, initiates 3 interactions
–
–
–
With the Buyer to acknowledge receipt of the Purchase
Order
With the Credit Checking Service to check Buyers credit
With the Inventory Service for product availability y Seller Response
–
The Seller reaction is guarded by the response interactions from Credit Checking Service and Inventory Service y If both interactions result are positive, the order is processed and the Purchase Order Response is sent y If either interaction indicate a negative result a
Purchase Order Reject message is sent to the Buyer

Buyer
PurchaseOrder
Seller createOrder
1
PurchaseOrder
PurchaseOrderAck
2 createOrderAck
PurchaseOrderAck
PurchaseOrderResp purchaseOrderResp
PurchaseOrderResp
5
15
Channels
Guards
Legend
Credit inventoryCheck
InvCheckReq
CheckCreditReq creditCheck
CheckCreditReq
3
CheckCreditResp createCheckResp
CheckCreditResp
4 inventoryCheckResp
InvCheckResp
Inventory
InvCheckReq
InvCheckResp
3

16 y Document type
–
–
Aliases WSDL message type, XSD type, XSD element
Supports future type systems y Token type
–
Specify name and type of piece of information y Uses WS-CDL Document type of the attribute y Token Locater type
–
Specify rules for selecting a piece of information y WS-CDL Document type y WSDL message part y XPATH query of document

17
<documentType name="purchaseOrderDocType" messageType="pons:purchaseOrderMsg"/>
<documentType name="purchaseOrderAckDocType“ messageType="pons:purchaseOrderAckMsg"/>

18
<tokenType name=“warehouseRef" type="xsd:anyUri"/>
<tokenType name="purchaseOrderID" type="xsd:int"/>
<tokenLocator tokenName="sns:purchaseOrderID" documentType ="purchaseOrderDocType" part="PO" query="/PO/Order"/>

19
y
–
Specify the observable behavior, in terms of the operations, a WS participant can perform y One or more WSDL interface type(s) named as behavior type y
–
Specify the mutual commitments, in terms of the
Roles, two WS participants are required to provide y Two WSDL interface types

20
<roleType name="Seller">
<behaviorType name="sellerForBuyer" interfaceType="sns:SellerPOPT"/>
<behaviorType name="sellerForCredit" interfaceType="sns:SellerCreditPT"/>
</roleType>

21
<relationshipType name="BuyerSellerBinding">
<role type="Buyer"/>
<role type="Seller"/>
</relationshipType>

22
y Identify a contact-point, through which two WS participants interact
–
– the service type of a participant, using Token type(s) within a reference marker the business process type implementing a WS participant, using Token type(s) within an identity marker y Identify a conversation between two or more WS participants
–
A conversation groups a set of related document exchanges, using Token type(s) within an identity marker

23
<channelType name="purchaseOrderCHT">
<channelDefinitions>
<channel type= ” purchaseOrderResponseCHT ” direction= “ respond ” >
</channelDefinitions>
<role type="Seller"/>
<reference>
<token name="warehouseRef"/>
</reference>
<identity>
<token name="purchaseOrderID"/>
</identity>
</channelType>

24
y Capture information shared between WS participants
–
Affect the progress of their common business transaction y State definitions
–
Define Documents y Typed with a documentType
–
Define Channels y Typed with a channel type
–
Specify the Role of the WS participant the state resides in

25
<stateDefinitions name="purchaseOrderChoreographyState">
<stateType name="purchaseOrderAckDoc" documentType="purchaseOrderAckDocType"/>
<stateType name="purchaseOrderDocAtBuyer" documentType="purchaseOrderDocType" roleType="Buyer"/>
</stateDefinitions>

26
y Enable WS participants to communicate and align their shared state
–
Align state that resides in one role with state that resides in the other role y Synchronized document exchange between two roles within a relationship
–
Atomic, request & accept of an operation through a channel y WSDL One way or request-response y Information flow
- request direction: fromRole towards toRole
- response direction: toRole towards fromRole

27
<interact name="inventoryCheck" onChannel="inventory-channel" operation="inventoryCredit" initiateChoreography="true">
<participate relationship="SellerInventoryBinding" fromRole="Seller" toRole="Inventory"/>
<align state="inventoryRequestDoc" with-state="inventoryRequestDoc"/>
</interact>

28
y Guard a set of activities
–
–
Express interest on the availability of one or more state information
When the state is/become available and a guard condition evaluates to true, the enclosed activities are enabled y In parallel or sequentially y Repeat: marks the re-enablement of a reaction y Choice: enables the mutual-exclusive enablement of a set of reactions

29
<react name="creditApprovalInventoryApproval" group="ApproveOrReject“ relationshipType=”BuyerSellerBinding” guard=
"cdl:getState(CreditCheckResponseDocAtSeller,
\“/Customer/Credit\”)[text() = 'success'] && cdl:getState(InventoryResponseDocAtSeller,
\“/Order/Inventory\”)[text()='available']">
<interact name="createOrderResponse“ … />
</react>

30
<react name="creditApprovalInventoryApproval“ …>
<interact name="createOrderResponse“ … />
</react>
<react name="creditApprovalInventoryApproval“ …>
<sequence>
<interact name="createOrderResponse“ … />
<interact name="createOrderResponse“ … />
…
</sequence>
</react>
<react name="creditApprovalInventoryApproval“ …>
<parallel>
<interact name="createOrderResponse“ … />
<interact name="createOrderResponse“ … />
…
</parallel>
</react>

31 y Interactions with common behavioral characteristics are combined to form a behavioral unit
–
–
–
–
Enumerate all the binary relationships interactions act in
Localize the visibility of state y Using state definitions
Prescribe alternative patterns of behavior y Using reactions
Enable Recovery y Backward: handle exceptional conditions y Forward: compensate already completed activities y Recursively combine Choreographies to form new
Choreographies

32
<choreography name="purchaseOrderChoreograpy" root="true">
<choreography name="buyerSellerChoreography”>
<interact name="createOrderInteract“/>
<interact name="createOrderAckInteract“/>
<choreography name="sellerResponseChoreography">
<interact name="createOrderResponse“/>
</choreography>
<choreography name="sellerRejectChoreography">
<interact name="createOrderReject“/>
</choreography>
</choreography>
<choreography name=“creditCheckChoreography”>
<interact name="creditCheck“/>
<interact name="creditCheckResponse“/>
</choreography>
<choreography name="inventoryCheckChoreography">
<interact name="inventoryCheck“/>
<interact name="inventoryResponse“/>
</choreography>
</choreography>

33
• WS-CDL describes XML schema for capturing the contract between multiple parties y Choreography complements Orchestration y Core concepts are Activity, State and Reaction y Spec under development in W3C Choreography WG
– Please download and comment if you are interested y Choreography and Orchestration standards needed for next generation Web Services platform