Key Value DB

RabbitMQ

"RabbitMQ is an open-source message-broker software that originally implemented the Advanced Message Queuing Protocol and has since been extended with a plug-in architecture to support Streaming Text Oriented Messaging Protocol, MQ Telemetry Transport, and other protocols."

ActiveMQ

Apache ActiveMQ™ is the most popular open source, multi-protocol, Java-based messaging serve

Kafka

Apache Kafka is a distributed event store and stream-processing platform.
Also, the routing logic of AMQP can be fairly complicated as opposed to Apache Kafka. For instance, each consumer simply decides which messages to read in Kafka.
In addition to message routing simplicity, there are places where developers and DevOps staff prefer Apache Kafka for its high throughput, scalability, performance, and durability; although, developers still swear by all three systems for various reasons.

KSQLDB

  • KSQLDB 101 uses Kafka streams to run queries over kafka, youtube

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