API General Howto
From Openprovider API documentation
API server
API commands should be sent over SSL to our API server on https://api.openprovider.eu. Each API command is an XML string that contains the data required for the respective command. The API will return an XML string to the sender, indicating the result of the command and optionally additional information.
PHP class for easy API inclusion
For easy integration in your existing system, Openprovider provides an example implementation in the PHP programming language. Other languages will follow in the future. The code provided consists of a wrapper class and an example implementation:
Other programming languages
In any other programming language, you can call the API by setting up a secured connection to https://api.openprovider.eu, and send the XML command over this connection. You will have to construct the XML command, and parse the XML response yourself.
Examples of the various API calls can be found in the description for each command.