[jackvanlightly]

Yes it does FIFO.

Just like RabbitMQ, Apache Kafka and many other distributed systems, writes go through an elected leader, who is able to ensure ordering guarantees.

Specifically with Apache Pulsar, each topic has an owner broker (leader) who accepts writes and serves readers.

It should be noted that Apache Pulsar supports shared subscriptions which allow two or more consumers to compete for the same messages, like having two consumers on a RabbitMQ queue. Here FIFO order cannot be guaranteed for all kinds of reasons.

[SuddsMcDuff]

See also: competing consumers pattern https://www.enterpriseintegrationpatterns.com/patterns/messa...