We strive to provide stable APIs that can operate over a long time period, but still maintain enough flexibility to improve and adapt the API over time. To accomplish stability in the API, we accept a custom HTTP header to indicate which publication date of the API you are requesting.
X-UltraCart-Api-Version: 2017-03-01
The current version of the API is 2017-03-01. As we enhance the API the object model may evolve slightly. By tracking the api version date that your client supports, we can maintain backwards compatibility.
Each language SDK will provide an example of how to add a default header that will be transmitted with each API call to make specifying the API version simple. See the individual resource for more details.
Requests will FAIL if a X-UltraCart-Api-Version is not specified.