THE NEXT STEP INWEB SERVICES

By Francisco Curbera,…

Memtimin MAHMUT

2012

Web Services : Method of communication between two electronic devices over the World Wide Web.

Software function provided at a network address over the web or the cloud.

Service that is "always on" as in the concept of utility computing.

Web Services : Method of communication between two electronic devices over the World Wide Web.

Software function provided at a network address over the web or the cloud.

Service that is "always on" as in the concept of utility computing.

İntends To Provide: SOC Standards-Based Realization of The Service-Oriented Computing Paradigm.

Traditional IT infrastructures: applications were managed and owned by one Enterprise.

At Present: applications are owned and managed by many business partners.

SOC : Middleware , Application.

Architecture: A componentized model.

Applications(services) in it: Declaratively define their functional and nonfunctional requirements and capabilities in an agreed, machine-readable format.

Services (discovery, selection and binding): Automated is a native capability of SOC.

To Support The SOC:

Web services: Must provide standards-based definitions of an interoperability communication protocol, mechanisms for service description, discovery, and composition as well as a basic set of quality of service (QoS) protocols.

SOAP, WSDL and UDDI: Provided open XML-based mechanisms for application interoperability,service description, and service discovery.

SOAP, WSDL and UDDI

SOAP : Simple Object Access Protocol İs a protocol specification for exchanging structured information in the implementation of Web Services in computer networks. XML : message format. Application Layer protocols, HTTP, SMTP : message negotiation and transmission.

WSDL : Web Services Description Language. İs an XML-based language that is used for describing the functionality offered by a Web service. provides a machine-readable description the service.

UDDI : Universal Description, Discovery and Integration.İs a platform-independent,XML-based registry and a mechanism to register and locate web service applications.İt is an open industry initiative, sponsored by OASIS,and to define how the services or software applications interact over the Internet.

SOC:A Componentized Model

Services: (Describe,public,interaction)(Discovery, selection, binding). Service composition: Main concern of the application development process. BPEL4WS : A language for creating service compositions in the form of business processes . OASIS. BPEL composition: İs a business process that interacts with a set of Web services. WS-Coordination: Defines a framework that supports the notion of pluggable coordination models. WS-Transaction: Defines two specific coordination protocols. WS-Policy, WS-Stack,WS_Security,…

Service Composition

Combines services following a certain composition pattern to achieve a business goal, solve a scientific problem, provide new service functions . Themselves become services, making composition arecursive operation. Provides a mechanism for application integration that seamlessly

supports cross-enterprise (business-to-business) and intra-enterprise application integration.

BPEL4WS A language for creating service compositions in the form of business

Processes. Supports a process-oriented form of service composition. Allows a set of existing Web services to be composed into a new Web

service using well-defined process modeling constructs; Provides a mechanism for defining service compositions in the form of

choreographies of Web services; a choreography consists of the aggregation of services according to certain business rules.

Provides extensive support for dealing with errors. Fault handler: structured model= “try-catch” blocks. Compensation handler: undo effect of action.it is typically invoked by a fault handler. Scopes:The units of fault handling and/or compensation in BPEL processes.

BPEL Composition

İs called Process. The services the process interacts with are called partners.

WSDL separates abstract service descriptions (interfaces and messages)specific deployments of the service.To provide multiprotocle access to a service. Only abstract interfaces are used in the partner definitions, which makes

BPEL compositions platform-and transport-independent. Activities: executed unit in BPEL. Primitive activities: İnvoke activity: Structured activities: Receive activity: Reply activity: Control links:

WS-Coordination

İs a general framework for implementing specific coordination types, where the coordination of Web services requires a shared context.

(complement BPEL) To provide mechanisms for defining specific standard protocols for use by transaction processing systems, workflow systems, or other applications that wish to coordinate multiple Web services.

The WS-Coordination framework defines three main elements commonly required by different coordination models:

A Coordination Context, An Activation service, A Registration service. Defines a framework that supports the notion of pluggable coordination

models. Defines the coordination context for use in environments where BPEL

scopes are distributed or span different vendor implementations; Provide coordination mechanisms that can be extended for specific

coordination protocols.

WS-Transaction

Defines two particular coordination types for (short-running) atomic transactions and (long-running) business transactions.

(complement BPEL) To provide mechanisms for defining specific standard protocols for use by transaction processing systems, workflow systems, or other applications that wish to coordinate multiple Web services.

WS-Policy, WS-Stack

WS-Policy: WSDL are enhanced by the Web Services Policy Framework(WS-Policy),

which extends WSDL to allow the encoding and attachment of QoS information to services in the form of reusable service “policies.”

WS-Stack: İs used to define, locate, implement, and make Web services interact

with each other. Web services stack is designed modularly, allowing one to use only the pieces of the stack required in a particular setting.

Service Composition Using BPEL4WS,WS-Coordination, and WS-Transaction The coordination client starts the coordination by sending a request

message to the Activation service of a chosen coordinator. A Coordination Context is then created by the Activation service. The Coordination Context contains :a global identifier, expiration data, the

port reference for the Registration service, other information. The port reference is a WSDL definition type that is used to identify an

individual port; it consists of the URI of the target port, contextual information that may include service-specific instance data.

Whenever the client initiates an invocation on a Web service, the Coordination Context must be propagated along with the application message.

The service being invoked can then find out about the Registration service’s port reference to register for the coordination protocol that it wishes to participate in; it can either directly register with the client’s coordinator, or use another (local) coordinator.

Conclusion

SOC is still in the early stages of development; fully dynamic business interactions following the SOC model are not foreseen in the immediate future.

The specifications presented here are important milestones on the way toward a complete standards-based framework to support service orientation.

Over the next few years, we will likely see the deployment and adoption of the full SOC model by business and scientific communities.

Teşekkür Ederim