The FM Restful API has several versions, this is normal as it’s an evolving project and must maintain backwards compatibility with older clients.

It’s the responsibility of the client/consumer to choose which API version to use, this is performed by setting a specific HTTP header. If this header is missing and/or invalid, them the system automatically process the request with the first version (which is version 1).

The HTTP header is X-FM-API-Version, that must be one of the released FM RESTful API versions, to obtain this list, please follow the topic: Obtaining the list of available versions.

It’s not required, but highly recommended that you include the X-FM-API-Version header in all performed requests. Follow: Obtaining the list of available versions, which will indicate the last version used; which probably is the one you should start using.

For example, with cURL, a typical call to FM System would be:

curl -H "X-FM-PublicKey: asdkjhadil37lasbmghgsjvsd" -H "X-FM-UnixTimestamp: 1410507373" -H "X-FM-Signature: jmfkdf74ikbs7ced586143aac59207a50mghgsjvsd" –H "X-FM-API-Version: 2" … …

The latest version of the application is constantly updated with bug fixes and new features. Previous versions are still accessible in order to guarantee backwards compatibility with external systems, however, these versions are no longer maintained or updated with bug fixes or new features