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Realisation of SOA using Web Services Advanced WS. Adomas Svirskas Vilnius University December 2005. Agenda. WS-* Specifications Advanced WS Architecture WS Taxonomy. Why the WS core is not enough?. We have got SOAP, WSDL, UDDI So we can develop, publish, discover, invoke Web Services

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Realisation of soa using web services advanced ws

Realisation of SOAusing Web ServicesAdvanced WS

Adomas Svirskas

Vilnius University

December 2005


Agenda
Agenda

  • WS-* Specifications

  • Advanced WS Architecture

  • WS Taxonomy


Why the ws core is not enough
Why the WS core is not enough?

  • We have got SOAP, WSDL, UDDI

  • So we can develop, publish, discover, invoke Web Services

  • But... this is about application integration

  • While the business world needs business process integration

  • Thus we need composable, orchestrated, transactable, secure Web Services


Current state of ws 1
Current State of WS [1]

  • The Web Services stack of standards has grown rapidly in the last three years from its original form as SOAP, WSDL and UDDI specifications

  • With it, the Web is moving towards being an open distributed computing platform with which we can build Service Oriented Architectures and Composite Applications


The reality ws nonexistent standards 2
The Reality - WS-Nonexistent Standards [2]

  • The numerous WS specifications introduced by various parties over the past few years show that there's a clear desire to fill out the WS architecture stack

  • Unfortunately, converting those specifications into actual industry standards is elusive

  • WS-This and WS-That

    • The specifications (collectively known as WS-*) are numerous and daunting.

    • A coalition of developers and architects from BEA Systems, IBM, and Microsoft authored most of them, though different specifications also include contributions from several other smaller companies.

    • Because the same author companies didn't write all the specifications, at least two different lists exist.


The reality ws nonexistent standards 21
The Reality - WS-Nonexistent Standards [2]

  • One can find complete lists of the WS-* specifications at:

    • http://msdn.microsoft.com/Webservices/understanding/specs

    • http://www-128.ibm.com/developerworks/webservices/standards/

    • http://dev2dev.bea.com/webservices/standards.html

  • Natural questions:

    • How do these specifications fit together?

    • Are they all really necessary?

    • If they are necessary, how and when will they become actual standards?


WS-*

  • These lists from Microsoft, IBM and BEA (there are more lists) cover pretty much every topic imaginable:

    • WS-Addressing

    • WS-Attachments

    • WS-BusinessActivity

    • WS-Coordination

    • WS-Discovery

    • WS-Enumeration

    • WS-Eventing

    • WS-Federation

    • WS-Inspection

    • WS-Manageability

    • WS-MetadataExchange

    • WS-Notification

    • WS-PolicyFramework

    • WS-Provisioning

    • WS-ReliableMessaging

    • WS-Resource

    • WS-Security

    • WS-Topics

    • WS-Transactions

    • WS-Transfer

  • Moreover, some areas have two, three, or more specifications devoted to them

  • There is a need for taxonomy of WS-* specs


Current state of ws 11
Current State of WS [1]

  • Within Web-based platform, software agents may

    • Exchange messages

    • Provide or consume services

    • Perform cooperatively units of work

  • Message exchanges and operation invocations may be part of a unit of work performed by software agents.

  • Instances of this unit of work have a precise lifecycle and often have a context.

  • Service compositions represent a particular type of unit of work.


Messages services uow 1
Messages, Services, UoW [1]

J-J Dubray, SAP Blog http://www.sdn.sap.com/irj/sdn/weblogs?blog=/pub/wlg/2261


Web services taxonomy 1
Web Services Taxonomy [1]

  • All standards and (the proposed specs) developed as part of the Web Services stack fall in one of these three categories

  • At the message exchange level, the message exchange protocol (SOAP) is layered on top of transport and syntax specifications. This protocol can be composed with other specifications for reliable and/or secure message exchanges

  • The WS-Addressing specification standardizes addressing mechanisms for the protocol


Ws standards architecture 1
WS-* Standards Architecture [1]

J-J Dubray, SAP Blog http://www.sdn.sap.com/irj/sdn/weblogs?blog=/pub/wlg/2261


Ws standards architecture w3c
WS-* Standards Architecture (W3C)

Web Services Architecture, W3C, http://www.w3.org/TR/ws-arch/#technology


Ws standards architecture m
WS-* Standards Architecture – M$

http://msdn.microsoft.com/webservices/webservices/understanding/specs/default.aspx


Ws standards architecture ibm
WS-* Standards Architecture - IBM

http://www-128.ibm.com/developerworks/webservices/standards/


Web services taxonomy 11
Web Services Taxonomy [1]

  • At the service level, the service definition specification (WSDL) can be composed with other specifications to add the concepts of Event and Resource

  • A directory (UDDI) may be used to store, search and retrieve service definitions.


Ws taxonomy uow 1
WS Taxonomy – UoW [1]

  • WS- RemotePortlets specification provides a service interface to user activities.

  • The foundation of the unit of work level is composed of Context, Lifecycle and optionally Coordination services for a particular type of unit of work.

  • The most basic type is a transaction: WS-AtomicTransaction (WS-AT), WS-Business Activity (WS-BA).

  • WS-BPEL provides more sophisticated capabilities and can be used to specify service compositions.


Ws choreography
WS Choreography

  • Finally, WS-CDL has the capability to describe any message exchanges performed by an arbitrary number of participants

  • WS-CDL is a choreography language as opposed to WS-BPEL which is an orchestration language. WS-BPEL is executable, WS-CDL is not.

  • In a choreography, it is the mere exchange of messages by agents which advances the state of the choreography.


Ws choreography1
WS Choreography

  • The decision process by which an agent decides to send a message is hidden from the choreography definition.

  • In an orchestration, an engine decides what to do next when it receives or sends a message, based on an orchestration definition.

  • A choreography definition may be used by each participant to configure the validation of the current message exchange instead of hard coding it.


Ws choreography2
WS Choreography

http://www.w3.org/TR/ws-cdl-10/#Purpose-of-WS-CDL


Ws standards architecture
WS-* Standards Architecture

  • The architecture is complemented by security (WS-Security, SAML ,…), management (WS-DM) and metadata (WS-Policy) specifications

  • Overall, these specifications have enabled the web to become a powerful distributed computing platform


Service component architecture sca
Service Component Architecture (SCA)

  • A major news as of 30 November: SAP, IBM, BEA, Oracle, IONA, Sybase, Siebel an others have announced the development of a new component model specifically designed for building service oriented architectures - SCA

  • SCA is a new component model based on the principles of Service Oriented Architecture

    • middleware and programming language neutral

    • offers a superior application model to support "Rich Clients" and construct RIAs (Rich Internet Applications)

  • http://dev2dev.bea.com/pub/a/2005/11/sca.html


Service component architecture sca1
Service Component Architecture (SCA)

  • SCA is also an assembly mechanism, based on the injection of dependency pattern (as in Spring framework) to create Modules from Components and Systems and Subsystems from Modules.

  • A module is composed of service components which run in the same process.

  • As such, SCA provides the means to compose assets which have been implemented using a variety of technologies as services can be accessed and reused in a uniform manner

  • Any component developed with SCA should be able to participate in a system with any other SCA component, regardless of its implementation language


References
References

  • [1] Dubray, J-J, SAP Blog 2005. Taxonomy and Architecture of Web Service Standards, http://www.sdn.sap.com/irj/sdn/weblogs?blog=/pub/wlg/2261

  • [2] Vinoski, S. WS-Nonexistent Standards. IEEE's Internet Computing, November 2004. http://www.iona.com/hyplan/vinoski/pdfs/IEEE-WS-NonexistentStandards.pdf

  • [3] Ferguson, D. et al. Secure, Reliable, Transacted Web Services: Architecture and Composition, 2003. http://www-306.ibm.com/software/solutions/webservices/pdf/SecureReliableTransactedWSAction.pdf

  • Papazoglou, M., Dubray, J-J. A Survey of Web service technologies. 2004, http://eprints.biblio.unitn.it/archive/00000586/


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