A web service is an application that allows disparate client applications to perform remote procedure calls on servers. The client applications and the server communicate with each other using XML messages formatted following the SOAP standard. The server publishes its supported remote operations via the WSDL standard for self description.
OneSpan Authentication Server supports the communication with client applications via SOAP over HTTP or HTTPS.
OneSpan Authentication Server comes with WSDL files for each of its supported SOAP interfaces.