A Model for Web Services Discovery With QoS Presenter: Razieh Niazi By: SHUPING RAN

Web Services Presents a promising solution for addressing platform interoperability problems Facilitates service composition using existing web services and promotes component reusability which has been a dream for the software engineering industry Web Service technology has a lot of potential, but the adoption rate has been very slow

This has been due to many factors such as lack of security and transaction support, quality of the web services and etc. Although there are emerging standards in these areas such as WS-Coordination (BEA, IBM, MS), WS-Transaction( BEA, IBM, MS), WS-Security (IBM, MS, Verisign) and…,There is not a coherent picture with full support in all these areas yet.

QoS,A Very Important Issue At the present time, UDDI looks up for Web Services based on the functional aspects of the desired Web Services.

Web Service needs yet to address such following questions: How will know the web service will meet my performance requirements such as 2 ms response time? Will the Web Service be reliable for my mission- critical system’s implementation?

To address these problems, the paper proposes a new service discovery model where quality of service is taken as constraints when searching for Web Services. The proposed framework is a regulated model that can co-exist with the current de-regulated UDDI registries. The current de-regulated registries can offer services to people to whom the quality of service is not important.

Whereas the regulated registries based on the new model can serve to the applications needing quality of service assurance. Actually, what we are looking for to discovery of web services is functional as well as non- functional requirements.

Web Service Supplier 1 Web Service Consumer 2 Web Service QoS Certifier 3 New UDDI Registry 4 There are four rules in this model:

The new Web Services registration and discovery model

Web service supplier offers Web Services by publishing the service into the registry like before. The Web Service Consumer need the web service offered by the provider. Web Service Supplier 1 Web Service Consumer 2

Is responsible to verify the claims of quality of service for a web service before its registration. The new UDDI registry is a repository of registered Web Services with lookup facilities. It is different with the current model of UDDI by having information about the functional description of the web services as well as its associated quality of service registered in the repository. Web Service QoS Certifier 3 New UDDI Registry 4

Web Services Registration Under New Model In the proposed model, Web service provider needs to supply information about the company, the functional aspects of the provided service as requested by the current UDDI registry, as well as to supply quality of service information related to the proposed Web service. The claimed quality of service needs to be certified and registered in the repository.

Web Service Provider Web Service QoS Certifier 1.Communicate its QoS claim to the Web Service QoS certifier 2. Check the claims The Certifier check the claims and certifies or down grade the claim 3-a. The result is sent back to the provider with certification identification information 3-b. This infor mation is also registe red in the certifier’s repository Ide ntified by a certificati on Id New UDDI Registry 4. Re gisters to the UDDI registry with Func tional Description of Se rvice + Certificate

Web Service Provider Web Service QoS Certifier The Certifier check the claims and certifies or down grade the claim New UDDI Registry 5. Communicate with the certifier to check The existence of the Certification Certifier’s Response 7.After successful checking, the registry then registers the service in its repository

Web Services Discovery and Invocation Under New Model A Web service consumer has certain functional and quality of service requirements. The consumer searches the UDDI registry for a web service with the required functionality as usual; plus he can add constraints such as required quality of service to the search operation

The search would or would not return a desired web service. Once a web service is found, the WSDL and certified QoS information is retrieved by the consumer. The consumer can verify the QoS claims with the certifier using the certification Id. Once s/he is happy with the finding, they can invoke the web service as the current model.

UDDI Data Structure The Existing UDDI model The New UDDI Model

Quality of Service Description To facilitate the description, the QoS is organized into the following categories: Runtime Related QoS –Scalability, Capacity, Performance, Reliability,.. Transaction Support Related QoS –Integrity Configuration Management and Cost Related QoS –Regulatory, Supported Standard, Completeness, Cost,.. Security Related QoS –Authentication, Authorization, Confidentially,….

References: [1] Shuping Ran, “A Model for Web Services Discovery With QoS”, CSIRO Mathematical and Information Sciences, Australia Template Design by PoweredTemplates.com'

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