A component of the METEOR-S
system on Semantic Web Services
and Processes
Keywords: P2P, UDDI, Web Services Registries, Semantic Web Services, Semantic Annotation of Web Services, Semantic Web Service Publication, Semantic Web Service Discovery, Domain Registry, JXTA based UDDI, Domain Specific Specialized Web Service Registry, Peer-to-Peer UDDI
Web services are the new paradigm for distributed computing. They have much to offer
towards interoperability of applications and integration of large scale distributed systems. To
make Web services accessible to users, service providers use Web service registries to
publish them. Current infrastructure of registries requires replication of all Web service
publications in all Universal Business Registries (UBR) which provide text and taxonomy
based search capabilities. Large growth in number of Web services as well as the growth in
the number of registries would make this replication impractical. In addition, the current Web
service discovery mechanism is inefficient, as it does not support discovery based on the
capability of the services and thus leading to a lot of irrelevant matches. Semantic discovery
or matching of services is a promising approach to address this challenge. In this project, we
have developed a scalable, high performance environment for Web service discovery among multiple
registries. This work uses an ontology-based approach to organize registries, enabling
semantic classification of all Web services based on domains. Each of these registries
supports semantic annotation of the Web services, which is used during discovery process.
We have implemented two algorithms each for semantic publication and discovery of Web
services. We believe that the semantic approach used in project will significantly
improve Web services publication and discovery involving a large number of registries. As a
part of the METEOR-S we have leveraged the peer-to-peer networking as a scalable
infrastructure for registries that can support automated and semi-automated Web service
publication and discovery. This project was carried on in two phases. They are:
1. Speed-R: Semantic Peer-to-Peer Environment of diverse Web Services Registries
JXTA based P2P network
Different kind of peers like Operator Peer, Gateway Peer, Auxiliary Peer and Client Peer depending on their roles. Implemented as different peer groups.
Each Operator peer controls a Web Service Registry. The role of the Operator peer is to control a registry and to provide Operator services for its registry. The Operator peer also acts as a provider for the Registries Ontology to all other peers who need it.
Gateway peer acts as an entry point for registries to join MWSDI. It is responsible for updating the Registries Ontology when new registries join the network. It is also responsible for
propagating any updates in the Registries Ontology to all the other peers. Gateway peer is not
associated with any registry.
Auxiliary peers act as providers of the Registries Ontology.
The Client peers are transient members of the peer-to-peer network, as they are instantiated only to allow users to use the capabilities of the MWSDI.
Peer Discovery and Pipe Binding protocols of JXTA are used to implemented additional peer interaction protocols(refer to publication).
While the Gateway peer is a single point of failure for Ontology updates, it does not impact querying and publishing of Web services, as they are provided by other peers. In case of failure of the Gateway peer, only initiation of new registries will not be possible. We have implemented
recovery mechanisms for restarting the Gateway peer.
The Peer Interaction Protocols we have implemented are the Operator Peer Initiation Protocol and the Client Peer Interaction Protocol
Supports Semantic Publication and Discovery of Web Services (refer to publication)