SOAP API
SOAP API can be built in the same way REST APIs are built with some slight changes to the properties that you will set up.
To begin building a SOAP API select New > API and then select SOAP from the drop down.
When building a SOAP API you will notice that the Input and Output Parameters have been replaced by 3 tabs: Schema, Input Message Parts, Output Message Parts:
These tabs allow you to build the requirements of the XML documents that will be exchanged.
The Schema enables you to build the structure of the document. Each can tag have be one of several types:
A Tag can also have 1 or more attributes which are defined in Name Value pairs by clicking Add attribute and enter the Name and Value.
Message Parts can be defined to come from the body or the header of the document and can be bound to a Schema Element by checking the Bind to Element check box and selecting a root level Element tag from the list.
After a SOAP API is created you can retrieve the WSDL in one of two ways described here Obtaining a WSDL file from a SOAP API Route.