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.

UDDI Registry

Web Service Consumer

Web Service Provider

Find

Retrie

ve

WSDL

Register(Publish

WSDL)

Request/Response

• 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 Supplier1

Web Service Consumer2

Web Service QoS Certifier3

New UDDI Registry4

• There are four rules in this model:

New UDDI Registry

Web Service Consumer

Web Service Supplier

Request/Response

Web Service QoS CertifierThe 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 Supplier1

Web Service Consumer2

• 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 Certifier3

New UDDI Registry4

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 ServiceProvider 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

Certificate

Certifier’s Repository

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 ServiceProvider Web Service

QoS Certifier

The Certifier check the claims and certifies or down grade the

claim

Certifier’s Repository

New UDDI Registry

5. Communicate with the certifier to checkThe existence of the Certification

1 2

3

3

4

6. Certifier’s Response

7.After successful checking, the registry

then registers the service in its repository UDDI’s Registry

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

BusinessEntity BusinessService bindingTemplate tModel1:n 1:n1:n

The Existing UDDI model

BusinessEntity BusinessService bindingTemplate tModel1:n 1:n1:n

qualityInformation

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'

Thank You