Superficially, a topic in a message queue would seem to be just a way to filter messages. And indeed, for ephemeral message brokers, that’s all they really are.
However, given the deeper connections frompersistent message brokers to both leader-based replication and databases, it is worth looking at message topics in a couple of other ways:
- A topic is a collection of logs is actually a group of partitions that have been given a common label.
- A topic is also an outer boundary for a query, analogous to a Database table.