ERN choreography using Secure File Transfer Protocol
DDEX defines two mechanisms to exchange ERN messages between two business partners. As such it establishes a reliable "pipe" to transfer ERN messages, other XML documents and/or files, including binary files containing the actual audio for Releases or Resources. The two mechanisms can be used for both ERN 3 and ERN 4.
First, DDEX has defined a Secure File Transfer Protocol standard which describes how SFTP should be used for exchanging messages and other files. Information about the second, using Web Services can be found here.
SFTP is similar to simple File Transfer Protocol (FTP) except that it encrypts both the command that executes the file transfer, and the data being transferred. This reduces the opportunity for eavesdropping during transfers. The specification for ERN Choreography for Cloud-based Storage version 1.8 which can be used for all versions of ERN is available here.
The standard sets out how:
Unique upload and download folders should be created;
Messages should be ingested in order of folder timestamp; and
Incoming and outgoing files follow a standardised, descriptive naming convention, including version and/or timestamp which reduces the possibility of processing the same file multiple times.