Simple Object Access Protocol (SOAP)

Simple Object Access Protocol. But it’s not simple.

It allows for describing services, similar to Swagger, but then in XML. It is described in a WSDL.

Messages are transmitted in a SOAP Envelope, which is an XML Schema (see XSD that basically has a root object with two properties: Header and Body. When sending a SOAP Message one must also specify a SOAP Operation. There is a number of ways to transmit one.

​​ Advantages and Disadvantages

The advantage of SOAP and XML is that it allows for unambiguous data formats: there is no discussion whether or not a message meets its schema. Another nice feature of XML is the concept of XML Namespaces, which allows for different definitions of an object with the same name depending on the context.

The advantage is also a disadvantage: it makes everything all the more complex, as a result of which one finds oneself Debugging too often why a specific message is not getting processed. Another downside is that XML is pretty bloaty, which results in requiring more bandwidth, and more computing power and memory to process XML.