CometD provides a scalability clustering solution called Oort.
Oort allows the server application to be split among multiple nodes, with different clients connecting to different nodes.
Oort interconnects the nodes so that Publish-Subscribe messaging works out of the box. This allows a publisher connected to a server to seamlessly broadcast messages to subscribers connected to different servers.
For clustered Peer-to-Peer messaging, CometD provides Seti. Seti allows a sender to send a direct message to the receiver, wherever it is located in the cluster.
Building on top of Oort and Seti, CometD also provides distributed objects and services.
Applications will be able to distribute data and work with naturally distributed data (for example, the number of subscribers to a particular chat room per node).
Distributed services allow applications to run code on a particular node, where the data resides, rather than pulling the data locally.
Learn more about the CometD clustering features in the reference manual.