Ably: Publishing over REST on behalf of a Realtime client example

In this example, we demonstrate how it is possible to publish a message over REST on behalf of a connected Realtime client. We create two Realtime clients: client A is the publisher client that the REST client publishes on behalf of, and the other simply subscribes to messages. client A in this example is configured with the client option echoMessages set to false thus preventing the message sent on behalf of itself via the REST library being echoed back to itself. See our REST Channel documentation for more details.