Understanding SOAP Message and Delivery Structure

As we know, SOAP is a XML based communication protocol, or a specification which enables exchange of messages between applications residing on remote systems. A SOAP message consists of three parts:

Envelope
Header and
Body

Among these three, envelope and body are the required part of a SOAP message while header is an optional part. Envelope contains both header and body. Besides transmitting text data SOAP message also contains metadata written in XML. It is contained in the header part. This metadata enclosed some instructions or information which is used in transmitting SOAP message. As mentioned above header is the optional part.

Body contains the actual text to be transmitted. In addition to these three parts body has sub element called “fault” which reports error and carry status information of message.
Consider the following example for a clear picture of SOAP message:

<soap:envelope>
<soap:header>
………..
</soap:header>
<soap:body>
………
<soap:fault>
……….
</soap:fault>
</soap:body>
</soap:envelope>

The SOAP message can be request type or response type. The system which generates the SOAP message is called the requestor while the one which responds to the request is called receiver.

In the process of transmitting SOAP message between requestor and receiver it might also get processed by intermediate systems which are referred as SOAP nodes. A SOAP node can transmit, process or relay the SOAP message. The processing done on a SOAP message by a SOAP node is known as SOAP actor.

SOAP request message body contains the name of the remote system to which it is meant to transmit and the input parameters. Similarly response message body has the name of remote system and the output parameter generated in response to the requestor.

So SOAP is a powerful framework for the communication of web services. Its importance lies in the light of the fact that SOAP messages are XML document which makes them platform independent and enables requests and responses to be performed over any transfer protocol.

| How to Parse an XML Document using DOM | Understanding Code Management in .NET | Understanding Enterprise Transaction Services in .NET | Understanding .NET Interface-Based Programming | Understanding Security Management in Web Services | Understanding SOAP Message and Delivery Structure | Understanding the Basics of Language Integrated Query (LINQ) | Understanding the Basics of Web Services using .NET | Understanding the Basics of XPath |