System APIs
The System service contains operations for negotiating API communication parameters including release ID. Software developers obtain a list of supported API release IDs from vCenter documentation or as part of the client library (SDK) they work with at the time they develop and test a solution. The software solution initiates a handshake by sending a prioritized list of release IDs supported by the solution. The server selects the first release ID it supports from the list.
Negotiating API release ID is necessary to use APIs utilizing inheritance based polymorphism. These include all VI/JSON APIs and a set of vSphere Automation APIs. vSphere Automation APIs that require API release ID state this in their documentation. Consult the Programming Guide and API reference documentation of specific operations for more information.