The choreography enabled by this standard is depicted in the two diagrams below. The actions on both sides (represented by red boxes) are exemplary only and only represent a typical information exchange in accordance with this standard. It comprises of these steps:
NewReleaseMessageand its Resources.
NewReleaseMessagefor the same Release appears in the Atom feed.
NewReleaseMessagethat is referenced in the Atom feed. The Release Creator should also make sure that the appropriate status code of 404 is returned upon a Release Distributor calling the now outdated
GET ERN Messageor
GET ERN Resourcecall;
NewReleaseMessageusing the URL provided in the Atom feed entry;
NewReleaseMessagein accordance with the relevant standard as agreed between the Release Creator and the Release Distributor;
NewReleaseMessageand extracts the URIs for each of the Resources that are part of the Release;
GET ERN Resourcecall.
DELETE ERN Messagemethod with the URL used to obtain the
NewReleaseMessagein Step 3.
Figure 1 – Basic ERN Web Service Choreography
Wherever this Clause references the
Figure 2 – Additional Commands in the ERN Web Service Choreography
Specifically not shown in the diagrams is the approach to exception handling.
It is for instance possible that a Release Distributor requests a
NewReleaseMessage based on the information received on an earlier
GET ERN Feed command – but that that
NewReleaseMessage no longer exists at that URL. In that case the response from the Release Creator’s web service could be a “redirect” with a 301 status code which could trigger the Release Distributor to request the Release using the information received in the reply.