- Currently, computer science is in the next period of abstraction.
- A generation ago we learnt to abstract from hardware and currently we learn to abstract from software in terms of SERVICE oriented architectures (SOA).
- It is the service that counts for a customer and not the specific software or hardware that is used to implement the service.
- In a later stage, we may even talk in terms of problem-oriented architectures (or more positively expressed in terms of problem solving oriented architectures) because SOAs are biased towards the service provider and not towards the customer that has a problem that needs to be solved.
- Service-oriented architectures will become quickly the leading software paradigm.
SOAs will not scale without signification mechanization of – service
discovery, service adaptation, negotiation, service composition, service
invocation, and service monitoring; and data and process mediation.
- Therefore, machine processable semantics needs to be added to bring SOAs to their full potential.
- Development of open standards (languages) and open source architectures and tools that add semantics to service descriptions
Three Layers of SESA
- Problem-Solving Layer
- Turns a service-oriented architecture into a domain specific problem-solving environment
- Common Services Layer
- The execution environment and the supporting infrastructure that maps the problem descriptions generated at the Problem Solving Layer to the services that can solve the problems
- Resource Layer
- Covers the deployment and provisioning of physical resource being responsible for the actual execution of the applications
Problem solving layer
- This layer turns a service-oriented architecture into a domain specific problem-solving environment.
- It represents the transparent interface to the user(s), where all computing resources are turned into or expressed as services
- Supports the full set of operations from an e-commerce framework: information negotiation, etc.
- Provides clear separation between business/process logic on one hand and the common service layer
Common Services Layer
- Provides an adaptive execution environment and the supporting infrastructure that maps the problem descriptions generated at the Problem Solving Layer to the services that can solve the problems.
- Existing architectures and standards from Web service and Grid areas (e.g. OGSA, WSRF, WSDL) which operate only at a syntactic level are semantically enriched and integrated into this layer.
- Semantically enrichment of SOAs that implement the Common Service Layer capabilities will help to automate: service discovery, service adaptation, negotiation, service composition, etc.
- This layer could be implemented using the W technology
- Responsible for actual execution of applications.
- All tasks that involve resources such as resource discovery, selection and negotiation for advanced or on-the-fly reservation of resources are supported and implemented in this layer.
- Covers the deployment and provisioning of physical resource (e.g. computers, data servers, and networks, usually connected into a Grid) and logical resources (e.g. application components or common services).
- This layer may relay on two prominent and widely discussed areas that deal with distributed resources in the context of service oriented computing are Ubiquitous Computing and Grid Computing