Discovery of Web Services in a Federated Registry Environment

1
Discovery of Web Services in a Federated Registry
Environment

• Kaarthik Sivashanmugam, Kunal Verma, Amit Sheth
• Large Scale Distributed Information Systems
  (LSDIS) Lab
• Department of Computer Science, University of
  Georgia

2
Outline

• Introduction
• MWSDI (METEOR-S Web Service Discovery
  Infrastructure)
• Extended Registries Ontology
• Characterizing Registry Federations
• TModel Support for Federations
• Publishing and Discovery
• Conclusions

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Introduction

• Service Oriented Architectures are being proposed
  to meet dynamic business environments
• Web Services are XML based instantiations of SOA
• UDDI is a crucial of part of Web Service Triangle
• UDDI aims to extend the reach ofthe enterprise
  both as provider and consumer of business
  services.

SOA Triangle
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Introduction

• Initial vision of UDDI
• Replication of centralized UBRs
• Businesses will be businesses
• Need privacy, security, trust
• Rise of private and semi-private registries
• UDDI version 3 (and presumably version 4) provide
  support for distributed registries

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Introduction

• This paper presents the idea of creating Registry
  Federations
• Registry Federation is defined as a group of
  co-operating registries that provide transparent
  access to all member registries
• Examples of federations
• Two companies X and Y share their registries
• Federation of all registries in Auto parts
  domains

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METEOR-S Web Service Discovery Infrastructure
(MWSDI)

• METEOR-S1 is a project which deals with all
  stages of Semantic Web Processes
• Our approach involves using the current industry
  standards infrastructure to add semantics
• MWSDI deals with adding semantics to UDDI
  registries
• Provides transparent access to UDDI registries
  based on their domain or federation

1 http//lsdis.cs.uga.edu/Projects/METEOR-S
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Extended Registries Ontologies (XTRO)

• Provides a multi-faceted view of all registries
  in MWSDI
• Federations
• Domains
• Registries

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Types of Queries Supported

• What is the access URL, available data model or
  type of the registry R?
• Does the registry R support the ontology O?
• Which are the registries available under the
  business domain B?
• Is the registry X a member of the registry
  federation Y?
• Which registries pertain to the domains that
  support the ontologies O1 and O2?
• Get all the registry federations that belong to
  the domain D?
• Find all the registries that are categorized
  under the node N in the taxonomy (or ontology) C?

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MWSDI Implementation

• Peer to peer network based on JXTA protocol
• Different types of peers based on their roles
• Gateway Peer
• Handles addition of new registries in MWSDI
• Responsible for updating registries ontology and
  propagating the changes to other peers
• Registry Operator Peers
• Each registry providing semantic publication and
  discovery must provide an operator peer
• Must implement generic publishing and discovery
  interface provided by MWSDI
• Potential mediators between UDDI and ebXML

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MWSDI Implementation

• Peer roles (contd.)
• Auxiliary peers
• Act as providers of Registries Ontology to their
  clients
• Propagate changes in the ontology to their
  neighbors
• Client peers
• Transient peers to provide a GUI for accessing
  (publishing services and querying for services)
  registries in MWSDI
• Peer protocols
• All peers must support JXTA specific protocols
• Peer Discovery Protocol and the Pipe Binding
  Protocol
• All peers must also support MWSDI specific
  protocols

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MWSDI Specific Protocols2

• Peer initiation Protocol
• Defines initiation of new registries in MWSDI
• Defines propagation of changes in Registries
  Ontology
• Client Peer Interaction Protocol
• Defined APIs and interactions for semantics
  publications and discovery
• Defines distribution of the registries ontology

2Verma et al., 2004 METEORS WSDI A Scalable
Infrastructure of Registries for Semantic
Publication and Discovery of Web Services,
Journal of Information Technology and Management
(to appear, 2004)
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Characterizing Registry Federations

• Can use relevant work in federated databases3 to
  characterize registry federations
• We characterize registry federations in three
  dimensions
• Data distribution
• Structural and semantic heterogeneity
• Autonomy

3A. Sheth and J. Larson, Federated Databases
Architectures and Issues, ACM Computing Surveys,
22 (3), September 1990, pp. 183-236
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Data Distribution

• Different schemes possible
• Hierarchical and non hierarchical
• Domains
• Replication
• Ownership
• MWSDI provides multi-dimensional partitioning
  with the help of Registries Ontology
• Domains and federations

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Structural and Semantic Heterogeneity

• Structural Heterogeneity
• Different data models like UDDI and ebXML
• Semantic Heterogeneity
• Which services have the same functionality
• MWSDI deals with semantic heterogeneity
• Only deals with UDDI registries
• Ontologies are used to resolve semantic
  heterogeneity
• T-Model directories to handle semantic
  heterogeneity across registries in a federation

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Autonomy

• Can registries be accessed independently of the
  federation ?
• Can the registries support different mechanisms
  for publications and discovery
• Autonomy in MWSDI
• Registries can be accessed independently
• Registries can support different mechanisms for
  semantic publication and discovery as long they
  support the generic interface

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TModels and TModel Directory

• SK can you please 3-4 slides for this

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Querying for a Registry

• R ltf, d, o, rgt
• f corresponds to the names of the registry
  federations
• d corresponds to the business domains
• o corresponds to set of ontologies
• r corresponds to a set of registry relationships.
• R lt F1,F2, D2, D3, O1, O2, O3, O4, gt

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Result of the sample query
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Conclusions

• Presented an approach for accessing distributed
  registries
• Used Registries ontology to provide multi faceted
  distribution and querying
• There will be many registries
• This is an potential approach to handle them