Introduction to SOAP protocol

SOAP(Simple Object Access Protocol.)
SOAP is a simple, lightweight XML-based protocol for exchanging information on the
Web.
SOAP defines a messaging framework that is independent from any application
or transportation protocol. Although, as mentioned, SOAP packets travel mostly as
HTTP-POST commands, SOAP neither mandates nor excludes any network and
transportation protocol.
The most important part of the SOAP specification consists of an envelope for
encapsulating data. The SOAP envelope defines a one-way message and is the atomic
unit of exchange between SOAP senders and receivers. The SOAP specification also
needs a request/response message exchange pattern, although it does not mandate a
specific message pattern. The remaining, optional parts of the SOAP specification are
data encoding rules for representing application-defined data types and a binding
between SOAP and HTTP.
Note:-Although SOAP is often associated with HTTP alone, it has been
designed according to general principles so that you can use SOAP
in combination with any transportation protocol or mechanism that is
able to transport the SOAP envelope, including SMTP and FTP.

Note: - SOAP is not magic—it is a simple XML-based, message-based protocol whose packets normally travel over HTTP.
The Web server must have a special listener ready to catch
incoming calls on port 80. These listeners are integrated with the Web servers, as is the
case with Internet Information Services (IIS).

A .NET Framework Web service is a Microsoft ASP.NET application with an.asmx
extension that is accessed over HTTP.
ASP.NET :- ASP.NET, as a whole, is part of the .NET
Framework that works on top of IIS, taking care of files with special extensions such as
.aspx and .asmx.