Parts of SOAP:-
SOAP consists of the following three parts:-
i) An envelope, which bears the content of the message.
ii) A set of Encoding rules to express instances of application defined datatypes.
iii) A convention for representing calls and responses.

Processing Models:-
This defines a distributed processing model,its participants,the SOAP nodes and how a
SOAP receiver processes a SOAP message.

SOAP Nodes:-
1) SOAP Sender
2) SOAP receiver
3) SOAP Message Path
4) Initial SOAP Sender
5) SOAP Intermediary
6) Ultimate SOAP receiver

Transport Methods for SOAP:-
Widely used methods for the transport of SOAP are SMTP and HTTP.

Merits:-
i) SOAP allows the use of different transport protocols.
ii) As the SOAP model tunnels fine in the HTTP response model,it can tunnel easily over existing
firewalls and proxies,without modifying the SOAP protocol.
Demerits:-
i) Because of XML format,SOAP can be slower than the middleware technologies like CORBA.
ii) The roles of interacting parties are fixed.Only one party can use the services of the other.