Adomas Svirskas with Bob Roberts & Michael Wilson 28 February 2006, San Sebastian, Spain

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1E-commerce State of the Art Report

Adomas Svirskas

Peer-to-Peer Business Communities:Mapping Public Choreography Protocols to Individual

Implementation Mechanisms

Adomas Svirskas

with Bob Roberts & Michael Wilson

28 February 2006, San Sebastian, Spain




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Adomas SvirskasAgenda

• Target Web Based Communities

• Service Oriented Architecture

• Business Protocols and Service Choreography

• Mapping to the Implementation Mechanisms




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Adomas SvirskasTarget Web Based Communities

• Communities of peers, as opposed to the master-slave model

• Communities requiring rather formal rules for their interaction– Business– Government– Public sector– Mix of the above

• Communities of changing rules




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Adomas SvirskasThe Enabler - SOA

• Service Oriented Architecture:– Services represent what businesses do– Services share only common message format,

which allows them to be independent (loosely coupled) and reusable

– These services communicate according to the standards – Web Services, WS-*, WS-I, etc.

• Service Oriented Architecture (SOA) is maturing:– Business take-up is increasing– Technical basis is strengthening




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Adomas SvirskasSOA/WS standards (just a few)

Service Composition

ComposableService

Assurances

Description

Messaging

Transports

BPEL4WS, WS-CDL

Security

XSD, WSDL, UDDI, Policy, Metadata

XML, SOAP, Addressing

HTTP, HTTPS, SMTP

ReliableMessaging

Transactions

Company Agreements,W3C

OASIS

W3C/OASIS

W3C

IETF




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Adomas SvirskasThe need for business protocols

• Disparate services alone do not solve the problem – they can cause chaos if used without an order

• In order to accomplish a common meaningful goal, the services should be used according to the business protocols

• The protocols represent the practical side of the business models

• They specify business message exchanges between the peers – business partners




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Adomas SvirskasService Choreography [5]

• Describes business protocols from the “global” point of view, i.e. commonly agreed rules come first

• It is a behavioral contract language for distributed systems of independent peers

• Is enacted individually by the peers, without any intermediary

• Is a declarative, non-procedural business collaboration backbone




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Adomas SvirskasSvc. Choreography Initiatives

• Common protocol (agree on the protocol in advance then follow it) based– ebXML Business Process Specification Schema

(ebXML BPSS or ebBP)• OASIS ebXML Business Process Technical Committee

– Web Services Choreography Description Language (WS-CDL)

• W3C Web Services Choreography Working Group

• Mediation (grow independently, resolve the protocol inconsistencies later) based– WSMO choreography and orchestration model

• WS Modeling Ontology Working Group




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Adomas SvirskasebBP and WS-CDL

• Although WS-CDL and ebBP address similar problem domains, the divergent foci of the two enables them to be layerable

• The WS-CDL focuses primarily (not only) on the Web Service perspective, while the ebBP describes the pure business message flow and state alignment. As such they are not mutually exclusive

• The ebBP v2.0 (which is nearing a vote for OASIS Committee Draft) supports mapping of Business Transaction patterns to abstract operations through the OperationMapping constructs, definition of business QoS guidelines, and it can be supported by CPPA, which maps to concrete WSDL

• These mechanisms provide the avenue for WS-CDL and ebBP compatibility.




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Adomas SvirskasSvc. Choreography - WS-CDL [2,5]

• WS-CDL is an XML-based language that can be used to describe the common and collaborative observable behavior of multiple services that need to interact in order to achieve some goal

• Common collaborative observable behavior is the phrase used to indicate describe the behavior of a system of services, for example buyer and seller services, from a global perspective

• Such observable behavior is described as a set of functions, possibly with parameters, that a service offers coupled with error messages or codes that indicate failure along with the return types for the functions offered.




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Adomas SvirskasService Orchestration in SOA/WS

• Orchestration specifies the behaviour of a participant in a choreography by defining a set of "active" rules that are executed to infer what to do next

• Once the rule is computed, the orchestration runtime executes the corresponding activity(ies).

• Orchestration assumes existence of an entity, which is the central point of control (i.e. the conductor in an orchestra) and governs overall workflow of activities, effectively composing a new service from existing services




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Adomas SvirskasChoreography vs Orchestration

Orchestration

From [1]

Orchestration is akin to traffic lights where events are controlled centrally, whereas

Choreography is more like a roundabout, where each participant is following a

prearranged set of rules.Paul Downey, http://blog.whatfettle.com/archives/000250.html




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Adomas SvirskasChoreography along with Orchestration

Business Analyst

WS-CDL

BPEL

Partner A

JAVA, C#, ...

Partner B

Choreography between A and B

A B

OrchestrationOrchestration

From WS-CDLSpecification [2]




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Adomas SvirskasCollaborative Business ProcessesCollaboration Definition

Distribution

Deployment

Orchestrationengine

choreography

CBP Choreography

The “business protocol” defining high-level interactions across administrative domains

Generation/Adaptation of actual executable processes and their views

From [4], (c) TrustCoM project




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Adomas SvirskasFlexible Choreography support

Company B

Company A

MSH

1

...

2

N

DeclarativeChoreography

Protocol

BSI

BSH

BSH

BSH

Mappingdefinition

Mappingdefinition

Mappingdefinitions

Subsystem II

Subsystem I

MSH

BSI

BSH

BSH

BSH

Mappingdefinition

Mappingdefinition

Mappingdefinitions

ExecutableOrchestration

"While business protocols are application specific, much of the software required to support such protocols can be implemented as generic

infrastructure components. For example, the infrastructure can (1) maintain the state of the conversation between a client and a service, (2) associate

messages to the appropriate conversation, or (3) verify that a message exchange occurs in accordance to the rules defined by the protocols (for

example WS-CDL) [3]




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Adomas SvirskasVirtualised Services

Domain A Domain B

Choreography (WS-CDL)

Gateway

Management

Security

Addressing

Monitoring

Gateway

Orchestration (WS-BPEL)

Service

Service

Service

Orchestration (WS-BPEL)

Service

Service

Service

Partner Partner

Management

Security

Addressing

Monitoring

RBVO




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Adomas SvirskasGateway anatomy

Monitoring/management handlers

Reactor

Monitoring

Handler management

Management

SLA

Supplier handlers

Consumer Handlers

Addressing

Encryption

Mapping table

Authentication

Decryption

Handler repository

• Patterns:– Acceptor-

Connector

– Chain of Responsibility

• Handlers:– Application

specific

– Application independent

• Rule-based mapping




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Adomas SvirskasRelated Work

• Pi4Tech (www.pi4tech.com) has launched an open source initiative Pi4SOA.org:– An interactive graphical WS-CDL editor

(Eclipse plug-in)– Validation of choreography descriptions– Scenario testing– Run-time monitoring– End-point skeleton (Java, WSDL) generation

and deployment (Axis)




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Adomas SvirskasConclusions

• Good business models come first

• Service Oriented approach allows flexible integration and single-platform approach

• Service choreography describes and helps to enforces the business protocols

• Intelligent support of choreography scripts by the peers is the key for adaptivity




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Adomas SvirskasThank you!

Adomas Svirskas

[email protected]

Researcher

Vilnius University, Lithuania

Kingston University London, UK




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Adomas SvirskasReferences

• [2] Booth, D 2005, From Web Services to the Semantic Web: Global Data Reuse. 2005. http://www.w3.org/2005/Talks/0110-dbooth-semweb

• [3] WS-CDL 2005, Web Services Choreography Description Language Version 1.0. W3C Candidate Recommendation, http://www.w3.org/TR/2005/CR-ws-cdl-10-20051109/

• [7] G. Alonso et al. Web Services Concepts, Architectures and Applications Springer Verlag 2004 ISBN 3-540-44008-9

• [11] M.D. Wilson, The TrustCoM Framework. A TrustCoM (www.eu-trustcom.com) workshop at PRO-VE’05, Valencia, Spain, 2005

• [12] S. Ross-Talbot, "Orchestration and Choreography: Standards, Tools and Technologies for Distributed Workflows", NETTAB Workshop - Workflows management: new abilities for the biological information overflow, Naples, Italy, 2005

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Adomas Svirskas with Bob Roberts & Michael Wilson 28 February 2006, San Sebastian, Spain