5.1 Web Service SOAP (simple object access protocol)¶

SOAP is a protocol used for message interchange that, although it can rely on several network protocols (e.g., JMS), is standardized for the http protocol only (W3C).

SOAP, which has seen its success with the rise of service-based architectures is based on XML with a header-body structure, divided into the following sections:

• Soap-Header (optional): this section contains data that are not related to the content of the information to be exchanged, but to the metadata related to the logging, routing, security and orchestration processes;
• Soap-Body (mandatory): this section contains data related to the information to be transmitted.

The interface Descriptor is based on the WSDL (Web Service Description Language) metalanguage and, in this sense, in order to allow systems to communicate with each other by means of SOAP, it is necessary that the same systems can exchange the WSDL.

The SOAP call, at last, uses only the POST method of http, with the possibility to send attachments to the request.