Introduction
The web services expose common functionality of the SharePoint that can be utilized by the client applications to extract and input data to SharePoint sites. If these exposed web services, do not provide you with the necessary functionality, you can always create custom web services that use the SharePoint object model.
Web services can be developed, using the old ASP.NET style by creating the .ASMX files or the Windows Communication Foundation (WCF) services. Using WCF, you can create either the SOAP style or REST web services.
For more information on the differences between ASP.NET web services versus WCF services, refer to MSDN at: http://msdn.microsoft.com/en-us/library/aa738737.aspx.
Simple Object Access Protocol (SOAP) uses XML behind the scenes to do client and server transactions. With SOAP, you can only use the HTTP POST method to do client and server transactions. It does not make use of the GET method, and hence does not provide better caching mechanisms for read-only...
