A Framework for the Smart Dynamic Selection of Web Services Access Points Marco Bianchi 10 June, 2004 Rome Workshop on QoS in Geographically Distributed Systems Giorgio Gambosi Carlo Gaibisso Flavio Lombardi

Goal of this presentation To show a “in progress” research activity in the context of Web Service Technologies. The focus of this activity is on the discovery of the “best” available Web Service Instance “Best effort”approach  QoS guaranteed approach

Web Service Architecture Model Reference: Web Services Conceptual Architecture (WSCA 1.0) – IBM – 2001 Service Registry Service Requestor Service Provider Service Description Service Service Description Publish Find Bind Static Bind Dynamic Bind

A model for a simple scenario Service Registry Service Requestor Service Instance 1 Service Instance n … Service Provider 1 Service Provider n 1 What happens in the Service Registry when a Service Instance goes down ? 2 How can the Service Requestor choose the most “comfortable” Service Instance? Service all implementing the same interface (i.e. tModel) Nothing. Current discovery standards (i.e. UDDI) could contain obsolete reference to Services Instances! Current discovery standards (i.e. UDDI) don’t provide any non-operational information about the run-time behavior of Service Instances! How the research community is trying to fill this gap? Using a declarative approach.

Web Services Technologies Relationships Discovery QoS Monitoring Integration of QoS declarations in the discovery process Monitoring in order to maintain the declared QoS Monitoring in order to discover “best” Web Services Monitoring in order to “certificate” the declared QoS

When ? Discovery QoS Monitoring Service Requestors: –do not intend to deal with of QoS aspects Service Providers: –are not interested in building up a SW/HW required infrastructure –are interested in avoiding providing services of “bad” quality Service Requestors: –do not intend to deal with of QoS aspects Service Providers: –are not interested in building up a SW/HW required infrastructure –are interested in avoiding providing services of “bad” quality

Main goal of the framework UDDI/WS Client Web Service Instance 1 1 … 3 Web Server 1 Web Server n CV 1 CV n Web Service Instance n Enhanced UDDI Registry still expose a standard UDDI Interface! 2 Enhanced UDDI Registry

Roadmap First phase: a basic scenario One Service Registry Small set of Web Service Instances Second phase: more complex (and realistic) scenario Several Service Registry Large set of Web Services Instances Authentication/Security UDDI API extension ……

Basic Scenario: introducing monitoring Agent Enhanced UDDI Registry Web Service Instance 1 … Web Service Instance n Web Server n Enhanced UDDI Monitoring Agent 1 Enhanced UDDI Monitoring Agent n Web Server 1 V i-1 =(x 1,..x m ) … V i =(x 1,..x m ) V i+1 =(x 1,..x m ) …

Enhanced UDDI Registry Architecture Enhanced UDDI Registry Enhanced UDDI Monitor Agent 1 Enhanced UDDI Monitor Agent n Statistics Archive UDDI Registry Agent Manager UDDI Extension Manager Points of Access Evaluator Request Catcher UDDI Client …

Basic Scenario: Discovery Operation In order to fully exploit the advantages derived by the ordered list is it necessary to modify existing clients? No, if clients adopt the Invocation Pattern suggested by UDDI Technical Committee. Enhanced UDDI Registry UDDI/WS Client UDDI Registry “Give me addresses associated to this tModel” Unordered list of addresses Ordered list of addresses

Basic Scenario: Publishing Operation Web Service Instance i Web Server Enhanced UDDI Monitor Agent i 3 1 Service Administrator 2 Enhanced UDDI Registry 4 5

Prototype implementation details Enhanced UDDI Monitoring Agent –Handlers for the AXIS Soap Engine –Monitored parameters: Availability Time of Completation Throughtput Enhanced UDDI Registry –JUDDI: an opensource Java implementation of the UDDI Specification

Concluding remarks Presentation of a framework for the association of a dynamic convenience value to Web Service Instances implementing a “best effort” approach More details in: M. Bianchi, C.Gaibisso, G.Gambosi, F. Lombardi “A Framework for the Smart Dynamic Selection of Web Service Access Points” Submitted to International Conference (ECOWS04)