A Model for Web Services Discovery With QoS

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					A Model for Web Services
Discovery With QoS

Presenter: Razieh Niazi
               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

                        W trie d
                         SD ve                      (P egis
                                                   W ubl ter
                         R Fin

                            L                       SD ish


                  Web Service        Request/          Web Service
                   Consumer          Response           Provider
• 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
• 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.
• There are four rules in this model:

      1    Web Service Supplier

      2    Web Service Consumer

      3   Web Service QoS Certifier

      4      New UDDI Registry
                                                 New UDDI
                                                  Registry         Re
                                     ve                                     te
                                ri e
                              et d                               Ce WS r (P
                           ( R a n S)                              rti DL ub
                         d                                            fie a
                      Fin SD d Q
                                L       o                                d n d l i sh
                         W ifie                                              Qo
                             rt                                                 S)

             Web Service                                                      Web Service
              Consumer                                                         Supplier






                                                 Web Service
The new Web Services                             QoS Certifier
registration and discovery model
 1   Web Service Supplier

• Web service supplier offers Web Services by
  publishing the service into the registry like

 2    Web Service Consumer

• The Web Service Consumer need the web
  service offered by the provider.
  3    Web Service QoS Certifier

• Is responsible to verify the claims of quality of service for a web
  service before its registration.

  4        New UDDI Registry

• 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 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
                     1.Communicate its                                                 The Certifier
Web Service          QoS claim to the
                                               Web Service                           check the claims
Provider                                                           2. Check the
                                               QoS Certifier                          and certifies or
                     Web Service QoS                                                  down grade the
                     certifier                                        claims              claim

                                         3-a. The result is sent back to the               Certificate

                                                    provider with
4. Re gisters to the
UDDI registry with
                                   certification identification information       3-b. This infor mation
Func tional Description
                                                                                  is also registe red in
of Se rvice + Certificate
                                                                                  the certifier’s
                                                                                  repository Ide ntified
                                                                                  by a certificati on Id

UDDI Registry
                                                                                   The Certifier
Web Service                 1                                   2
                                               Web Service                       check the claims
                                               QoS Certifier                      and certifies or
                                                                                  down grade the

                          5. Communicate with
                          the certifier to check
                          The existence of the

   New                             6. Certifier’s Response
UDDI Registry
                7.After successful checking, the registry                              Repository

                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
• 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
• 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
                 1:n                     1:n                         1:n
BusinessEntity         BusinessService          bindingTemplate             tModel

                            The Existing UDDI model

                 1:n                      1:n                         1:n
BusinessEntity         BusinessService           bindingTemplate             tModel


                           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,….
[1] Shuping Ran, “A Model for Web Services
  Discovery With QoS”, CSIRO Mathematical
  and Information Sciences, Australia

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