Currently Mendix supports SOAP services through WSDL, XSD and JSON schema's.
I hope support for OData can also be added, currently if we manually create a JSON schema for our OData service we can consume the OData service.
In the EDMX file the following information can be retrieved.(XML format)
-the datatype of the attributes
If the support for EDMX is added a OData service can be just as easily consumed as a soap service.
With a OData source you can fetch the EDMX file by putting /$metadata behind the URL of the ODatasource.
A visual representation of the information in the EDMX schema, that can by fetched through /$metadata can be found here:
API detials (Data types of the attributes within the objects)
Since the introduction of WCF by Microsoft for realizing a SOAP service is the EDMX schema the standard.(Exists over 10 years)
The successor of WCF, WebAPI and MVC for realizing a SOAP service also uses the exact same schema.
My guess is that a lot of the costumers that depends SOAP for exchanging data will be grateful.
Here is a list of platforms and services that uses SOAP http://www.odata.org/ecosystem/