DNS-based Discovery System in Service Oriented Programming

Service Oriented Programming (SOP) is an emerging paradigm for grid computing and distributed applications development. SOP models an application as a composition of services, i.e. software components either local or remotely provided by third-party organizations. In SOP service information, like location and interface description, is often stored in registries (like UDDI) distributed in internet. Before using a service, applications need to know in advance its endpoint address or the location of the registry where to look for service information. In this scenario, dynamic discovery of service registry as well as inter-registry co-operation would be a very desirable feature. This paper proposes an approach for service discovery based on DNS messaging. It provides applications with DNS-based querying mechanisms to publish and discover on the network either the location of service registries or the endpoints of web services. This approach was implemented in a middleware system that uses the Multicast DNS technology and the DNS-based Service Discovery specification to provide respectively the communication infrastructure and a standard naming convention for service registries and web services advertisement and retrieving in a LAN.