Yes, per channel. Every message published to a channel receives a server-assigned, monotonically increasing 17-digit timetoken. Messages on a channel therefore form a single, globally consistent ordered sequence, and subscribers receive them in that order with no client-side sequencing required. The same ordering holds when replaying history through Message Persistence, because stored messages carry the timetoken assigned at publish time.
A subscriber that falls behind the publish rate may miss messages rather than receive them out of order. The subscribe buffer holds a limited number of recent messages and discards the oldest first. To guarantee a subscriber can recover every message it missed, enable Message Persistence and replay from the last received timetoken - see Connection Management.
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