UNDERSTANDING THE SOAP PROTOCOL AND THE METHODS OF TRANSFERRING BINARY DATA
Over the recent years, the introduction of XML has revolutionized the way data is transferred between systems. XML, similar to the popular HTML of common web pages, is a meta-language made up of non-binary ASCII text. [PDF]
http://www.freestylemedia.com.au/Freestylemedia%20White%20Paper%20-%20SOAP.pdf