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Service-oriented Architectures

Understand SOA concepts, OASIS reference model, web services, WS-BPEL, choreography, business rules, security, and more. Learn about mediation, composition services, and applications in the evolving architecture landscape.

danielhoward
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Service-oriented Architectures

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  1. Service-oriented Architectures Veli Biçer

  2. Agenda • What is SOA? • Main Concepts • OASIS SOA Reference Model • Open Service Oriented Architecture • Web Services • WS-BPEL • Choreography • Service Oriented Analysis & Design • A few words from SODSL

  3. What is SOA? • “A paradigm for organizing and utilizing distributed capabilities that may be under control of different ownership domains.” OASIS RM for SOA • “A form of distributed systems architecture characterized by service abstraction, message orientation, description orientation, and platform neutrality” W3C Web Services Architect. • “an evolution of the Component Based Architecture, Interface Based Design (Object Oriented) and Distributed Systems such as DCOM, CORBA, J2EE and the Internet in general” Adobe Systems

  4. What is SOA? • Application Architectures: • Monolithic Application • Object-Oriented Application • Client-Server • 3-tier, n-tier • Distributed Objects • Component Orientation • Service Orientation

  5. What is SOA? Mediation Composition Services Applications Choreography Business Rules Security Trans. & Reliabil. Discovery Description

  6. What is SOA? Internet Mashup Services Internet Internet I P EMR Archetype Repository National ID Management Electronic Claim Processing LIS Billing RIS/ PACS HIS Mobile Client UI Application Logic (Client) Application Logic (Server) Business Processes SaaS

  7. Main Concepts • Service • A service is a contractually defined behavior that can be implemented and provided by a component for use by another component. • The mechanism by which needs and capabilities are brought together • Well-defined, self-contained modules that provide standard business functionality and independent of the state or context of other services

  8. Main Concepts • Service Description • consists of the technical parameters, constraints and policies that definethe terms to invoke the service. • Contains information necessary to interact with the service • The concept of visibility • W3C’s Web Service Description Language • ebXML Collaboration Protocol Profile • OWL-S Semantic Markup for Web Services • Web Service Modeling Ontology (WSMO) • WS-Policy

  9. Main Concepts • Advertising • Pull methodology: potential service consumers request the service provider to send themthe service description. • Push methodology: the service provider, or its agent, sends the service description topotential service consumers. • Discovery • A potential consumer obtains information about the existence of a service,its applicable parameters and terms.

  10. Main Concepts • Registry/Repository • A component where users can store and manage artifacts required fortheir enterprise to function. • Includes artifacts that require sharing among more than oneuser (such as XML schemas and web-service descriptions) • OASIS ebXML Registry/Repository • OASIS Universal Description and Discovery Interface (UDDI)

  11. Main Concepts

  12. OASIS SOA Reference Model • Define the essence of service oriented architecture • To create a vocabulary and a common understanding of SOA • Based on concepts present in all SOA’s • A Reference Model defines SOA in an abstract sense. Example: • Abstract = Service Description • Concrete = WSDL

  13. OASIS SOA Reference Model

  14. Open Service Oriented Architecture (OSOA) • alliance of industry leaders that share a common interest (www.osoa.org): • defining a language-neutral programming model that exploits SOA characteristics and benefits.

  15. Service Component Architecture (SCA) • Provides an assembly model for services • To simplify and standardize development • Control Files or pragmas • Six values that define a service: • Interfaces • Implementation • Policy Assertion • Required Interfaces • Resources • Valid Operation Sequences

  16. Service Component Architecture (SCA)

  17. Service Component Architecture (SCA) • Modules • Components and Component Types • Component Implementation: • Interfaces

  18. Service Component Architecture (SCA)

  19. Service Component Architecture (SCA)

  20. Service Component Architecture (SCA) • Apache Tuscany • http://incubator.apache.org/tuscany/ • Eclipse SOA Tools Platform Project • http://www.eclipse.org/stp/ • IBM DeveloperWorks SCA • http://www-128.ibm.com/ developerworks/library/specification/ws-sca/

  21. Web Services • Web Services Technology Stack Choreography(WS-BPL,ebBP) Mediation(WSMO,ESB,Biztalk) Enterprise(WS-BPEL,WS-Management) QualityOfService(WS-Security,WS-ReliableMessaging, WS-Addressing,WS-Transaction) Description&Discovery(WSDL,WS-Policy,UDDI,ebXML) Messaging(XML,XSD,SOAP,SOAPAttachment) Transport (HTTP, HTTPS, SMTP,FTP)

  22. WS-BPEL • Web Services Business Process Execution Language • a notation for specifying business process behavior based on web services • Owned by OASIS, originally created by IBM and Microsoft

  23. WS-BPEL • BPEL Constructs: • sequence: executes one or more activities sequentially. • flow: executes one or more activities in parallel. • switch: executes one of several paths based on the value of a condition. • while: executes a specified activity as long as a condition is true. • invoke: calls a web service. • receive: receives an incoming web services call. • reply: sends a response to a received web services call. • variables: defines any global variables the process uses. • assign: allows copying and manipulating data using XPath • partnerLink: specifying the roles and message exchanges between communication partners

  24. Choreography • Describe collaborations of parties by defining from a global viewpoint their common and complementary observable behavior • Information exchanges, the jointly agreed ordering rules… • Unlike processes, more than one party is included • More like a global contract which can be realized by more than one parties • W3C’s Web Services Choreography Description Language (WS-CDL) • ebXML Business Processes (ebBP)

  25. Cardiology Hospital X Laboratory Hospital Y Insurance Company Place Lab Order Order Result Confirmed Check Insurance

  26. Choreography RIS,LIS HIS HIS • “Collaborative Business Process Support in IHE XDS through ebXML Business Processes” ICDE2006

  27. Enterprise Service Bus • A point-to-point Web service may offer significant value:

  28. Enterprise Service Bus • What if we have more than one client: • We need something to simplify this

  29. Enterprise Service Bus • Enterprise Service Bus route messages between WSs:

  30. Enterprise Service Bus

  31. Enterprise Service Bus • A BPEL Server can be a basic ESB • But introducing following limitations: • A process defined using BPEL will commonly need to access local objects • A process often needs to communicate with other software outside its own environment. • Processes commonly need to access data • Business processes commonly involve people

  32. WSMO • Providing a standard for describing semantic web services. • Stands for the Web Service Modeling Ontology • http://www.wsmo.org • WSMO Working Group • 79 Members

  33. WSMO WSMO WG A Conceptual Model for SWS WSML WG WSMX WG A Formal Language for WSMO An Execution Environment for WSMO A Rule-based Language for SW

  34. WSMO

  35. WSMO Mediation Example

  36. Service Oriented Analysis & Design • IT Lifecycle proposed by IBM

  37. Service Oriented Analysis & Design • “The wrong approach is to look at the silos, identify interesting data and plant a service on it. The right direction is to lay out the scenarios you want to carry out, and see where they touch silos. A point of tangency is where there might be an opportunity for a service. Services should not be driven bottom up from technology, as DHS folks are proposing, but rather from the top down—with the use cases.” • Grady Booch on an interview about SOA • http://www.gcn.com/print/25_20/41302-1.html “This is not to say SOA is a bad thing. Like any technology, you have to approach it in meaningful ways. SOA is very useful for gluing systems together, but it does not address the internal architectures of systems”

  38. A few words from SODSL DomainAnalysis DomainDesign Domain Implementation Feature Model Coordination Model SODSL Feature Classification Partitioning Strategy SODSL Generator Feature Modularization Process Generator COSEML SOA (WSMO) Feature Constraints Services Ontology Ontology Parser Reasoning Engine Rule Engine

  39. A few words from SODSL Feature Model COSEML & DSL Code Generation Rules Process Service Platform

  40. A few words from SODSL • Traditional  Function Oriented • Object OrientationData Oriented • Component OrientationStructure Oriented • Service OrientationProcess Oriented • Build for change • Message Oriented, Loosely Coupled • Rule based

  41. Thank you for your attention… • Questions?

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