Document Metadata Subscription - IHE

IHE Technical Framework Supplement - Document Metadata Subscription (DSUB)4.4.1 Publish/Subscribe Actors and PatternsPublisher↓ Publish 4.4.2.3Notification Broker← Subscribe 4.4.2.1Subscriber↓Notify 4.4.2.2Notification RecipientFigure 4.4.1-1 Publish/Subscribe Actor Diagram10551060Figure 4.4.1-1 shows a general publish/subscribe pattern, expressed in the usual IHEActor/Transaction diagram. The actors and transactions described in this section are “abstract”,in the sense that the purpose of these descriptions is to provide the common underlying transportinfrastructure for publish/subscribe. A profile using the publish/subscribe pattern will provide thecontent and actual implementable details for the above actors and transactions within the contextof that profile. Such a profile may chose to omit certain actors or transactions, or to requirespecific grouping with other IHE actors.The following subsections discuss the various patterns applicable to a publish/subscribeimplementation, which are intended to help systems designers and profile authors toappropriately apply publish/subscribe to different types of data interchanges.4.4.1.1 General Publish/Subscribe Pattern1065The general publish/subscribe pattern contains four separate actors, which communicate via threetransactions. The actors are Notification Broker, Publisher, Subscriber, and NotificationRecipient. While in many practical cases some of these actors may be grouped, the most generaldiscussion of publish/subscribe can occur when these actors are considered individually.4.4.1.1.1 Notification Broker1070The Notification Broker keeps track of all subscriptions, and based on the information receivedin a Publish transaction it sends notifications to the appropriate Notification Recipients. Thisactor is the receiver of the Subscribe transaction, which represents subscription requests,2009-08-10 42 Copyright © 2009: IHE International