Transformational Interactions for P2P E-Commerce

service composition, service conversations, UDDI, WSDL, WSCL, SOAP Peer-to-Peer (P2P) technology brings distributed computing capabilities to individuals, creating a new perspective of networkcapable devices in the role of resources that can be combined to enable new capabilities greater than the sum of the parts. As services become more loosely coupled and increasingly autonomous, heterogeneous distributed services should be able to discover and converse with each other dynamically, with or without human intervention. Current paradigms of service interaction require service developers to hardcode their logic to adhere strictly to pre-defined conversation policies. We propose extending the P2P environment with facilitator services that can leverage “reflected” XML-based specifications (borrowed from the B2B domain) to direct and enable coordinated sequences of message exchanges (conversations) between peer services. In addition, we introduce transformational interactions – abstract specifications of typed message exchanges that have been extended with the ability to specify transformations to be applied to both inbound and outbound documents. Together, these two mechanisms can free service (and, to some extent, client) developers from having to couple business and conversation logic. We also describe our implementation of a prototype facilitator service. The facilitator service is an extremely lightweight solution that can direct, track, and mediate spontaneous conversations between services and clients, thus enabling services to carry out an entire conversation without the service developers having to implement any explicit conversation control or document type transformation mechanisms.