Sync Message Streams let you broadcast JSON messages at a high rate to an elastic group of subscribers. Like WebRTC Data Channels, Message streams offer relaxed delivery guarantees by readily dropping messages that cannot be delivered promptly. The result is a low-latency, near-zero lag publish/subscribe tool for your realtime apps, a good complement to Sync’s high-fidelity state synchronisation primitives.
Unlike Documents, Lists, or Maps, Messages in a Stream are ephemeral, avoiding the latency hit of persistent storage and connection recovery support. This makes it ideal for applications that are latency-sensitive and/or forgiving to missed messages:
With ACLs disabled, any SDK client can create and publish to a message stream. Note that, if you later enable ACLs on your Sync instance, only the REST API allows Message Stream creation. The ability to publish messages or subscribe to a stream is governed by the
read permissions, respectively.