11.6 Reliable Posting of Service Operation
The SData protocol guarantees reliable Posting on asynchronous operations. It forces the consumer to allocate a universally unique identifier (UUID) and passes it via the trackingID parameter. Thanks to this UUID, the service provider can detect duplicate requests and reject them.
There is only one issue here. If the provider receives a duplicate POST for a given trackingID, it SHOULD return its normal 202 response, not a 4xx error. This guarantees the request is idempotent (safe to be called several times) from the consumer side.