Π 4 Technologies Building distributed systems using WS-CDL and FpML 16th May 2007 Steve Ross-Talbot...

π4 Technologies

Building distributed systems using WS-CDL and FpML

16th May 2007Steve Ross-Talbot

CTO Hattrick Software

Chair W3C Web Services Choreography WG

Chair Pi4 Technologies Foundation

Thanks to

Pi4 Technologies Foundation Ltd (www.pi4tech.com)

Hat Trick Software Ltd (www.hattricksoftware.com)

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Agenda

• Background

• Why is process important?

• Why use WS-CDL?

• What is WS-CDL?

• Deep dive

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Background

• FpML– Financial Products Markup Language– Policed by ISDA

• FpML today is– A set of documents that describe the structure

of how to encode financial products in XML– XMLSchema to enable validation of correct

message formats– There are a set of sequence diagrams to govern

when to send what to whom

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Background• Typical message:

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Background• Typical flow:

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The problem

• How do we know what the context is for any FpML message

Is it NovationConsentGranted?

Is it NovationConsentRefused?

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The solution today

• Hope and pray ….– Add meta data around the FpML package– Agree meta data with your clients

NovationConsentGrantedAllocationId 9876

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The problem today

• Behavior first. Content second.

• No agreement on meta data needed, because there are no fully defined processes

• What makes a NovationConsentGranted a NovationConsentGranted is the process not the message. The message is a consequence.

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The problem today

• Sequence diagrams are not enough

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• Buyer, Seller, Credit Agency, Shipper.• Buyer barters with the Seller to get a price • Buyer accepts a price and places an order• Seller checks Buyers credit worthiness• Seller requests delivery from Shipper• Shipper sends delivery details to Seller and to Buyer

• How do we write this down today?– Bubble and stick– Sequence diagrams– WS-CDL

An Example

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Buyer Seller

Shipper

CreditAgency

An Example - Bubble and Stick

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Buyer Seller

• Buyer request a quote from the seller.

• Seller responds with a quote.

• Quotes may timeout.

• Buyer MAY update quote and request the update from the seller.

• Seller MAY respond with the update quote.

• Buyer MAY accept the quote.


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Buyer Seller

Shipper

CreditAgency

• Seller checks credit worthiness.

• Seller requests delivery from Shipper.• Shipper sends delivery details back to Seller and to Buyer.

• If Buyer accepts the quote.

• If Credit worthiness is okay


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An Example - Sequence diagrams

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Why Process?

• All messages exist in a context.– E.g. fpml:RequestAllocationConfirmation message will not be

relevant in an Affirmation (Trade) business process

• It’s not what you do but the way that you do it– Did I expect to get an fpml:AllocationConfirmed message after

sending an fpml:ConfirmAllocation?– Ordering is important because it defines how you behave.

Behaviour directly impact interoperability. Can I work with Mega Bank?

• Standardising the business processes increases STP rates and enables the market to grow.– The differentiator is the product being sold not how the back office

deal with it.

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Why WS-CDL?

• Need to describe a business process from an architectural neutral perspective.

• Need to describe a complex model in which participant roles may change.

• Need to model a message oriented business processes as well as having an option to leverage Web Services.

• Need to use a recognised standard to avoid vendor lock-in.

• Need to have open source tools for description to avoid vendor lock-in.

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What is WS-CDL?

• Standard from the W3C

Enables processes (protocols, business processes) to be described from a neutral or global perspective, enabling the services to run as peers whilst guaranteeing interoperabilty of those services.

Described processes based on their common collaborative behavior through message passing, called interaction.

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Where does WS-CDL fit?

• XMLSchema describes format• WS-CDL described behavior

Format + Behavior = systems

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FpML 4.3

• Open source tool for process description

• XMLSchema (with meta data identified)

• Scenarios validated against a WS-CDL model

• Scenarios for review, Html for review, BPMN for review

• Generation of roles directly into code or through UML into code

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Opensource toolsuite

• Pi4 Technologies Foundation open source tool suite– www.pi4tech.org– Eclipse plugins (pi4tech update site)– Graphical modeling environment– Static type checking (completeness, lock free, race

condition free)– Export• WS-CDL• WSDL• HTML• BPMN

– Generate• UML artifacts• Java (for J2EE)• Java (for Axis)• BPEL

– Monitor• Against WS-CDL

description• Legacy and/or

generated

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FpML 4.3 model overview

Confirming the ContractConfirming the

Contract

Placing an Order

Executing the Trade

Allocating the Trade

Confirming the Contract

Handling theContract

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FpML 4.3 model designerPlacing an

Order

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FpML 4.3 modelPlacing an

Order

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FpML 4.3 modelExecuting the

Trade

Allocating the Trade

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FpML 4.3 model Handling theContract

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FpML 4.3 modelConfirming the

Contract

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FpML 4.3 model

• In a nutshell:– Types

• Roles - encapsulations of behavior• Participants - encapsulations of end-points that play roles• Information types - messages and useful variables• Channel types - to facilitate communication• Bindings of channel types to message types through identity

(called session typing)

– Ordering/Business Processes• Interactions over channels (sending and receiving of messages)• Ordering and dependencies

– Situated decisions @roles– Project out participant behaviors

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FpML 4.3 confirmationsAllocationAlleged [Acc2All] OR RequestAllocationConfirmation [All2Acc], AllocationUnmatched [Acc2All] ORRequestAllocationConfirmation [All2Acc], DO Loop

Loop {Choice {

1.ModifyAllocationConfirmation [All2Acc], IF (policy) THEN ModifyAllocationMatch[Acc2All]

2. AllocationMismatched[Acc2All]3. CancelAllocationConfimation[All2Acc], (AllocationCancelled OR AllocationAlreadyMatched)[Acc2All]4. AllocationAlreadySubmitted [Acc2All]5. RequestAllocationMatched[Acc2All], AllocationMatched[All2Acc], ConfirmAllocation[Acc2All], AllocationConfirmed[All2Acc]6. AllocationAlreadyMatched[Acc2All]

} if you do any of 2, 3,4 5,6 then break the loop}

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FpML 4.3 Confirmations

• Project out the behavior of the Alleger and the Accepter.

• AllStateMachine policies the Alleger role.– When it sends

• AccStateMachine policies the Accepter role.– This guy receives

• How do you know they are correct– Statically - advanced typechecking shows conformance.– At runtime - with session mgmt and monitoring against

expected behavior……. For example …..

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FpML 4.3 confirmationsAllocationAlleged

RequestAllocationConfirmation

AllocationUnmatched

RequestAllocationConfirmation

ModifyAllocationConfirmationModifyAllocationMatchModifyAllocationConfirmationModifyAllocationMatchModifyAllocationConfirmationModifyAllocationMatchCancelAllocationConfirmationAllocationCancelled

RequestAllocationConfirmationRequestAllocationMatchedAllocationMatchedConfirmAllocationAllocationConfirmed

RequestAllocationConfirmationModifyAllocationConfirmationModifyAllocationMatchModifyAllocationConfirmationModifyAllocationMatchRequestAllocationMatchedAllocationMatchedAllocationConfirmed

HOW CAN WE DETERMINE IF THESE SEQUENCES OF MESSAGES ARE CORRECT?

ConfirmAllocation

RequestAllocationConfirmationRequestAllocationMatchedAllocationMatchedConfirmAllocationAllocationConfirmed


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ConfirmAllocation


FpML 4.3 confirmations

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FpML 4.3 scenario

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CDL generation• CDL State machine per service

– Send• <NameOfExchange>Send.java

– Receive• <NameOfExchange>Receive.java

– SilentAction• <NameOfSilentAction>Activity.java

– Predicate• <NameOfPredicate>Predicate.java

– Channel (discovery)• <ChannelInstanceName>Channel.java

– Stubs• Preserve behavior of the distributed

system described Make calls to the context to retrieve, manipulate and store state.

• State is stored in a context per participant service and passed to the stubs

– Context• Hashmap (name, object)• Name is the name of the

variable in the CDL description

• setVariable(….)• getVariable(….)

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CDL generation

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CDL generation<NameOfExchange>Receive

public class PublishMessageExReceive

extends DefaultActivityExtension

implements ReceiveActivityExtension{

…….

public void processMessage(ExtensionContext context,

Message message)

throws ServiceException

{

}

}

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CDL generation<NameOfExchange>Send

public class InvalidCounterpartyExSend extends DefaultActivityExtensionimplements SendActivityExtension

{

…….public java.io.Serializable getMessageContent(

ExtensionContext context)throws UnresolvedConstraintException,

ServiceException {

java.io.Serializable ret=null;…….return(ret);

}

}

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CDL generation<NameOfSilentAction>Activity

public class PrepareCounterPartyExceptionActivity extends DefaultActivityExtensionimplements SilentActivityExtension

{…….public void process(ExtensionContext context)

throws ServiceException {

……}

}

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CDL generation<NameOfPredicate>Predicate

public class SuccessfulLookupPredicate extends DefaultActivityExtensionimplements PredicateExtension

{…….public boolean isSatisfied(ExtensionContext context)

throws UnresolvedConstraintException, ServiceException

{boolean ret=false;…….return(ret);

}}

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CDL generation<ChannelName>Channel

public class ConfirmationAlledgerChannel extends DefaultActivityExtensionimplements ChannelCreationExtension {

{…….public EndpointReference discover(

ExtensionContext context, String serviceType, String endpointReferenceType,ServiceRegistry registry, SemanticAnnotations semantics)

throws DeferProcessingException, ServiceException {EndpointReference ret=null;

ret = registry.discover(serviceType, endpointReferenceType);return(ret);

}}

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CDL generationContext:

Is a hash map.

Object val = context.getVariable(“businessEvent”);context.setVariable("businessEvent",val);

Contexts are local to the participant service

StubClass {

stubToFillIin(Context c){

v1 = c.getVariable(“varName”);……c.setVariable(“varName”,v1);

}}

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Demo• CDL editor

– FpML model– End point projections– Generation to HTML and BPMN– Generation to Java

• Confirmations– Inject some messages– See what happens at the Acceptor and the Alledger– Monitor the participants against the choreography description

• Uses – generic CDL aware gateways and a monitor from Hat Trick Software, – Any JMS messaging, including QPid, – J2EE container

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Demo

Accepter

Alledger

Confirming the Contract

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Demo

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Demo

Message contents: Could introduce an xslt style sheet to pretty print.

Logical communication channels between participants: NullChannel is for out of sequence messages.

What actually happened: Externally observable message exchanges.

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Demo

Message Sequence Number for the monitorBusiness identifier for the transaction

Sending Participant (Service)

Receiving Participant (Service)

Logical operation nameStatus (Initiated means sender sent, Completed means receiver received)

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Questions

Π 4 Technologies Building distributed systems using WS-CDL and FpML 16th May 2007 Steve Ross-Talbot...

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