If you have some traditional applications running from on-premise, they may use open protocols such as MQTT, AMQP, STOMP, Openwire, WSS, etc. When migrating to the cloud, instead of re-engineering the application to use SQS and SNS (AWS proprietary), we can use Amazon MQ (managed Apache ActiveMQ) for communication.
Doesn't “scale” as much as SQS or SNS because it is provisioned
Runs on a dedicated machine (can run in HA with failover)
Has both queue feature (SQS) and topic features (SNS)
