QoS- Chord4S achieves higher data availability Web based services

SERVICE-ORIENTED Computing (SOC) is emerging as a new aradigm for developing distributed applications. Service discovery, among the most fundamental elements of SOC, is critical to the success of SOC as a whole. Traditional service discovery approaches of the web services technology. Centralized service registries used by UDDI may easily suffer from problems such as performance bottleneck and vulnerability to failures as the number of service consumers and requests increase in an open SOC environment. This inherent disadvantage prevents web services from being applied in large scalable service networks. The Peer-to-Peer (P2P) technology provides a universal approach to improving reliability, scalability, and robustness of distributed systems by removing centralized infrastructures. Structured P2P can potentially improve the scalability of service discovery, directly applying DHTbased P2P approaches to decentralized service discovery may be weak in guaranteeing the availability of published service descriptions. A Chord-based decentralized service discovery approach that supports service description distribution and discovery in a P2P manner. Chord is selected because it is well recognized for its flexibility and scalability and is considered suitable in large-scale SOC environments. The new routing protocol of Chord4S for service discovery. Chord4S of three main parts: service identifier, QoS specification, and syntax specification. Original routing protocol to support discovery of multiple functionally equivalent services at different successor nodes with one query, which is necessary for negotiation of a Service Level Agreement and selection of optimal service providers. The reason is that requirements for more QoS attributes increase the level of difficulty to find satisfactory service descriptions, and hence requires visiting more successor nodes.