10.3.4. Dynamic Exchange Routes

A dynamic exchange route connects an exchange on one broker (the source) to an exchange on another broker (the destination) so that a client can subscribe to the exchange on the destination broker, and receive messages that match that subscription sent to either exchange.

Dynamic exchange routes are directional. When a dynamic exchange route is created from broker A to broker B, broker B dynamically creates and deletes subscriptions to broker A's exchange on behalf of its clients. In this way broker B acts as a proxy for its clients. When a client subscribes to the destination exchange on broker B, broker B subscribes the exchange to broker A's source exchange with the subscription that the client created. Clients subscribing to broker B effectively subscribe to both the exchange on broker B and the dynamically routed exchange on broker A.

The consuming broker creates and deletes subscriptions to the source broker's dynamically routed exchange as clients subscribe and unsubscribe to the destination exchange on the consuming broker. It is important to note that the dynamic exchange route is a competing subscription, so the destination broker is a message consumer like any other subscriber.

In a dynamic exchange route, the source and destination exchanges must have the same exchange type, and they must have the same name. For instance, if the source exchange is a direct exchange, the destination exchange must also be a direct exchange, and the names must match.

Internally, dynamic exchange routes are implemented in the same way as exchange routes, except that the bindings used to implement dynamic exchange routes are modified if the bindings in the destination exchange change.

A dynamic exchange route is always a pull route. It can never be a push route.