DDEX has defined three different protocols by which a record company (or aggregator) can communicate ERN messages to online retailers (or aggregators):
- Web services;
- Release-by-Release via FTP; and
- Batched FTP.
The order in which Releases need to be ingested in the first two cases is obvious from the order in which the information is being provided to the recipient. The batched FTP approach, however, deserves a closer look:
The batched FTP protocol stipulates that the sender of the ERN messages should place all ERN messages, plus all the required Resource files, into a folder on the FTP server. This file is to be named after "the date and time of its creation" in the form YYYYMMDDhhmmssnnn.
It is this batch time stamp, and not the creation date/time of the files within the batches that determines the order in which a recipient needs to process the communicated Releases.