OnlineAPI is one of the most used SOAP API modules as it provides many of the essential ordering functions as well as rep and customer control functions. To you these functions, you must first configure an API User Account. The credentials will be passed in the credentials object and the function would be called with no-auth.
Some of the functions in these modules have updated equivalents in the newer RESTful WebAPI. We recommend using the newer versions whenever possible and current and future development is now focused on RESTful WebAPI and not SOAP WebServices.
When encountering functions with different versions available, it is recommended to use the newest version.