7.4.1 Introduction

The approach to PieMessage deliveries defined in this clause is symmetric. Metadata Providers and Release Distributors will need to publish and maintain a web service. The diagram below shows a typical exchange enabled by this choreography:

This clause defines the minimum that a web service provider needs to publish in order to be conformant with this standard. Additional services may be added on top of the features of the standard. For instance, the call to subscribe to a feed is defined herein to only apply to cases where the query leads to a single result. When a query leads to multiple results, the standard calls for an error to be returned. An extended service might offer the means to handle multiple results in an automated fashion. 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.