The GMD API uses HTTP verbs and a REST full endpoint structure. An access key is used as
the API Authorization framework. Request and response payloads are formatted as JSON, using
UTF-8 encoding and URL encoded values.
To use this API, you need an account and an access key, which can be created in your account.
GMD provides the creation of test keys to discover and test the API at your own convenience.
The difference between a live key and a test key is that a live key actually sends a message,
while a test key does not. However, when you send a message using a test key, you will get a
fake created object back.
GMD uses standard HTTP status codes to indicate success or failure of an API request. Codes in
the 2xx range indicate that a request was successfully processed.
In case of an error, the body of the response includes a json formatted response that tells you
exactly what is wrong.