How do you apply the XML, SOAP, UDDI, WSDL, ebXML, and messaging concepts to P2P applications? Can you develop applications that expose Web service interfaces over the P2P infrastructure and use SOAP to expose your P2P Web service interfaces? There is no conceptual problem in doing this. Chapter 20, "Using SOAP with P2P," demonstrates how to use SOAP over P2P networks. You can also go one step further. Recall that WSDL is the grammar used to describe Web service interfaces, and UDDI tModels represent technical fingerprints. You can describe the interfaces of your applications using WSDL, and you can also publish your P2P Web service applications as technical fingerprints using the UDDI tModel structures. This means that you can publish your P2P Web services on an XML registry like UDDI, search for P2P Web services published by other peers, describe your P2P Web services using a grammar such as WSDL, and bind your P2P Web services with concrete implementations using a binding mechanism, like SOAP. For example, let's consider an application scenario in which a company has already written its WSDL interfaces, hosted its Web services on a SOAP server, and published all the relevant information and documents on a UDDI registry (or probably an ebXML registry). Now the company has come across a prospective customer base in a community of peers sharing a P2P infrastructure. The company would like to expose its existing Web services to the community of P2P users. For this purpose, the company will be required to do the following:
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