SOAP is an XML based message called SOAP envelope and has following essential
elements
Envelop name space - This name space does not directly point to a
dtd file but to a URL alias like http://www.w3.org/2003/05/soap-envelope
Envelop encoding type – this element specifies the SOAP encoding
rules to be followed. This name space does not directly point to a dtd
file but to a URL alias like http://schemas.xmlsoap.org/soap/encoding/
Envelope name – Name of the SOAP message
Header – Meta information of the Envelop, This element is optional
Body – Application data container, This element is required
Lets look at the XML below
<soap:Envelope
xmlns:soap=http://schemas.xmlsoap.org/soap/envelope/
soap:encodingStyle=" http://schemas.xmlsoap.org/soap/encoding/"
>
<soap:Header>
<!—This is an optional block, header content here -->
</soap:Header>
<soap:Body>
<!—This is a required block, request or response data comes here-->
</soap:Body>
</soap:Envelope>
Let us look at a simple SOAP request-response login authentication routine.
There is no Header element, remember!! Its optional
lg:Login is the method we are invoking on a service hosted at urn “MyServer”.
The service "urn:MyServer" can host a lot of other methods also.
Example a movie information service can host other methods like lg:MovieList,
lg:TheatreList etc
