XenServer includes a XML-RPC based API, providing programmatic access to the extensive set of XenServer management features and tools. The XenServer API can be called from a remote system as well as local to the XenServer host. Remote calls are generally made securely over HTTPS, using port 443.

XenServer SDK: There are five SDKs available, one for each of C, C#, Java, PowerShell, and Python. For XenServer 6.0.2 and earlier, these were provided under an open-source license (LGPL or GPL with the common linking exception). This allows use (unmodified) in both closed-and open-source applications. From XenServer 6.1 onwards the bindings are in the majority provided under a BSD license that allows modifications.

Citrix Project Kensho provided a Common Information Model (CIM) interface to the XenServer API and introduces a Web Services Management (WSMAN) interface to XenServer. Management agents can be installed and run in the Dom0 guest.

Details here: http://bit.ly/2rHMhTI