Issuing a SOAP request and parsing a response

SOAP stands for a Simple Object Access Protocol. And, indeed, the protocol is very simple and extensible, since it only defines the container parts of the message being transferred, such as, body, header, and fault. But it does not strictly define format or validation rules for the content of the message apart from requesting the message to be XML-compatible.

Also, SOAP has several low-level protocol bindings such as, SOAP-over-HTTP, SOAP-over-SMTP, and SOAP-over-JMS. HTTP binding is the most popular choice for SOAP-based web services.

Usually, a SOAP web service is associated with a Web Service Definition Language (WSDL) and probably a set of XML Schema Definition (XSD) that more precisely define the contents of the service operation requests and responses. But strictly speaking those are not required by the SOAP standard, even though they definitely help to understand the service input and output formats.

There is also a family of WS-* (WS-I...