Revised bindings text

Attached below is revised draft section 3.2 (SOAP) bindings 
introductory text. This removes mention of the RPC encoding and incorporates the 
SOAP AI work.

I plan to incorporate this in the bindings revision, please let me know of 
any issues (SOAP 1.2 and SOAP 1.2 Primer references to be adjusted)

Thanks

regards, Frederick
Frederick Hirsch
Nokia

3.2 SAML 
SOAP Binding

SOAP is a lightweight protocol intended for exchanging 
structured information in a decentralized, distributed environment. It uses XML 
technologies to define an extensible messaging framework providing a message 
construct that can be exchanged over a variety of underlying protocols. The 
framework has been designed to be independent of any particular programming 
model and other implementation specific semantics. Two major design goals for 
SOAP are simplicity and extensibility. SOAP attempts to meet these goals by 
omitting, from the messaging framework, features that are often found in 
distributed systems. Such features include but are not limited to "reliability", 
"security", "correlation", "routing", and "Message Exchange Patterns" 
(MEPs).

A SOAP message is fundamentally a one-way transmission between 
SOAP nodes from a SOAP sender to a SOAP receiver, possibly routed through one or 
more SOAP intermediaries. SOAP messages are expected to be combined by 
applications to implement more complex interaction patterns ranging from 
request/response to multiple, back-and-forth "conversational" exchanges.

SOAP defines an XML message envelope that includes header and body sections, 
allowing data and control information to be transmitted. SOAP also defines 
processing rules associated with this envelope and an HTTP binding for SOAP 
message transmission.

The SAML SOAP binding defines how to use SOAP to send and receive SAML 
requests and responses.

Like SAML, SOAP can be used over multiple underlying transports. This SAML 
SOAP binding has protocol-independent aspects, but also calls out the use of 
SOAP over HTTP as REQUIRED (mandatory to implement).