7.5 Atom-based Web Service Choreography

The approach to metadata deliveries defined in this clause is asymmetric. Only the Metadata Provider needs to publish and maintain a web service. The diagram below shows a typical exchange enabled by this choreography:

The provisions defined in Clauses 7.4.2, 7.4.3, 7.4.4 and 7.4.5 also apply to the Atom-based choreography with the exceptions that:

• Metadata Providers and Release Distributors need to agree the URLs for the subscribe and unsubscribe calls as well as the Atom request call; and

• That the Metadata Provider must make sure that the URLs placed in the responses to web service calls are (a) valid and (b) active.

Not shown in the above diagram is the ability to unsubscribe to a service.

Also not specifically shown is the ability to access documents that are referenced from the PieMessage. However, the process is the same as depicted above.