SOAP Services

SOAP is an XML-based protocol that lets you exchange info over a particular protocol (can be HTTP or SMTP, for example) between applications.
It stands for Simple Object Access Protocol and uses XML for its messaging format to relay the information.

SOAP is an XML based protocol that allows applications to exchange information over http.
It is a communication protocol
It is platform independent
It is based on XML, HTTP and SMTP
It is language independent

Any soap message can contain an optional header, which might contain additional information not strictly related to the method being called.
For example a client might use the header to send its credentials so that the web service can record who accessed its methods and when.
SOAP is the only protocol that support objects and structures.
The only requirement for an object fed to (or returned) is that it must be serializable.
SOAP is also the only protocol that supports output arguments using ByRef.

web.config Changes

All three protocols are enabled by default although you can disable one or more of them by editing your local web.config file.
In a production web service you might want to drop all the add tags except the SOAP one.

<configuration> 
   <system.web> 
      <webServices> 
         <protocols> 
            <add name="HttpSoap" /> 
            <add name="HttpPost" /> 
            <add name="HttpGet" /> 
            <add name="Documentation" /> 
         </protocols> 
      </webServices> 
   </system.web> 
</configuration>