Preferences in semantics-based Web Services Interactions Justus Obwoge

 Automated Web Services interactions require addressing heterogeneity/integration, dynamic change, scalability, & performance challenges  Translations to enable interoperability between disparate services  Consumers need to efficiently and flexibly locate (discovery) and connect to supplier systems  Other automation efforts: Composition, binding & execution,  Integration of user-preferences with those of semantics techniques for enabling automated services interactions  Align matching user-side heuristics and non-client mechanisms (.  Transparency in the use of notions of user-metrics Introduction

Interresting Motivation SOA Maturity model for Services (adopted IFEAD, 2008) Increasing complexity

Semantics in Web Services Support: machine processability Reasoning and Formalisation Shared & Explicit semantics Web Service focus Area: Discovery, composition, execution, monitoring Issues: Services representation, conceptual modelling, increasing maturity Semantics

Web Services Discovery and Location task Request Web service 2 Web service n Web service 1 Service ConsumerService Providers f(R, A 1 ) f(R, A 2 ) f(R, A n ) Match function

Matchmaking: Degree of Match hasInput : hotel & City hasOutput: price hasInput: LuxuryHotel & City hasOutput: price inR: a request input inA: an advertisement input degreeOfMatch(inA, inR)  Paolucci et.al. ISWC02 if inR=inA then Exact if inA immediateSubclassOf inR then Exact if inA subclassOf inR then Plug-in if inR subclassOf inA then Subsume otherwise Fail |Exact| > |Plug-in| > |Subsume| > |Fail| Service Matchmaker Request Advertisement Exact R A Subsume Travel Ontology Accommodation Hotel B&B LuxuryHotel

Issues in semantics Matchmaking Advertisement Request Hotel … … LuxuryHotel … Acknowledement: Jorge Cardoso f(R(Input), A(Input) 1 ) Service Matchmaker Architectural construct of matchmaking: i.e. registries & broker based algorithms (Pair-wise-computations) w.r.t underlying ontology Adequacy of the used indices in the matching: i.e. Syntactic, Semantic. & importance of accuracy in discovery e.g. weighting & distance. Representation of “user-wish” of task for the actual matching.

A need for the Capture of user criteria & Heuristics in Services discovery Definition of preferences – i.e. preference algebra Base preferences {i.e. I prefer x to y in a retrieval} Complex preference constructors i.e. (Kiessling, 2002) User criteria and Preferences Advertisement Request Hotel … … LuxuryHotel … f(R(Input), A(Input) 1 ) Service Matchmaker ?

Prefs SM candidate services User Preference Semantics {x=[p1, p2,…,pn]} * Degree of Match (for params) {y =[=, , , ,  ]} Preferences enhanced Semantic matches Integration of Semantic formalisms with Preferences

Architecture of a Preference-based approach Semantics Logic Matchmaker Semantic logic Component Preference Component Request (Elements) Request (Attributes, prefs) Semantic Match (SM) prefsSM Advert. (Elements) Advert. (Elements) Semantics based Preferences & Semantics-based Attributes Preferences enhanced Semantic matches

Service Request Loader Semantic matching Component Preferences Component Ranked Services Comparer Query With Preferences Elements{a1, a2…an} Preferences(x1,x2..xn} S Services S SP Services {s1>s2>s3…} SP Analysis and evaluation

Conclusions  Logics-based Semantics techniques w.r.t. an Underlying ontology improve services retrieval accuracy i.e. recall and precision space.  User-Preference over semantics enhance specifications by which resources are matched and discovered based on capabilities, and requesting contexts Comprehensive approaches to the use of semantics in SOA are needed:  Data, function/operation, execution, QoS, Management  Addressing the Complete Web Service “Metaphor” from: Annotation, Publication, Discovery, Composition, Binding, Execution

References Kiessling, W. Hafenrichter, B. (2002) Optimizing preference queries for Personalized Web services. Universität Augsburg Technical Report, Institute of Computer Science, University of Augsburg, July 2002 Paolucci, M. Kawamura, T. Payne, T.R. Sycara, K. (2002a) Semantic matching of web services capabilities. James Hendler (Eds), Proceedings in: The semantic web-ISWC 2002, First International semantic web conference, Sardinia, Italy, June 9-12, 2002 Thank You!!