Presentation on theme: "Service Oriented Architecture Reference Model"— Presentation transcript:
1 Service Oriented Architecture Reference Model An informal SOA Ontology
2 Reference ModelAn abstract framework for understanding significant relationships among the entities of some environment.Consists of a minimal set of unifying concepts, axioms and relationships within a particular problem domain.Is independent of specific standards, technologies, implementations, or other concrete details.
4 Service Oriented Architecture Service Oriented Architecture is a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains.Goal of this reference model is to define the essence of Service Oriented Architecture
5 Why Service Oriented Architecture? Drivers:Large scale Enterprise systemsInternet scale provisioning of servicesReduce the cost of doing businessBenefitsBuild scalable, evolvable systemsScalable because minimizes assumptionsManage complex systemsEncourage re-use of business function
6 Why is it different? SOA reflects the reality of ownership boundaries CORBA, RMI, COM, DCOM, etc. all try to implement transparent distributed systemsOwnership is of the essence in SOASOA is task orientedServices are organized by functionGetting something doneSOA is inspired by human organizationsIt worked for us, it should work for machines
7 What is not in the RM Service composition Organizational framework Choreography, orchestrationProcess Oriented ArchitectureOrganizational frameworkWho is doing what to whomSpecific technologiesnot even specific architectures
9 Service A mechanism to enable access to one or more capabilities using a prescribed interfaceconsistent with constraints and policies as specified by the service description.
10 Visibility Awareness Willingness Reachability Visibility is the relationship between service participants that is satisfied when they are able to interact with each otherAwarenessService descriptionDiscoveryWillingnessPolicy & contractReachabilityCommunication
11 InteractionInteracting with a service involves performing actions against the serviceThe extent to which one system can effectively interpret information from another system is governed by thesemantic engagement of the various systems.The semantic engagement of a system is a relationship between the system and information it may encounter.
12 Real World EffectThe purpose of using a capability is to realize one or more real world effects.At its core, an interaction is “an act” as opposed to “an object” and theresult of an interaction is an effect (or a set/series of effects).The real world effect is couchedin terms of changes to the state shared bythe participants and stakeholders ina service interaction
14 Conditions and Expectations PolicyConstraint representing the intention of a participant in a serviceContractConstraint representing an agreement between two or more participants.
15 Description The service description represents the information needed in order to use, manage or provide a service.Service reachabilityService FunctionalityService PoliciesService Interface
16 Execution ContextThe execution context is the set of infrastructure elements,process entities, policy assertions and agreements that areidentified as part of an instantiated service interaction,and thus forms a path between those with needs and thosewith capabilities
17 Is a Reference Model an Ontology? Establishing a vocabularyA lot of definitionsThe RM glossary has 28 entriesFormality was consideredAudience is not formalMechanical processing of RM not expected
18 What about UML UML obvious choice for an architecture spec But, Inheritance (is-a) relationship almost never usedExtraneous precisionE.g. we tried to define Service, not count the number of service providersIt’s so ugly <duck/>