I don\'t have any previous experience with *MQs and I\'m looking to build knowledge on JMS and message queues in general. That way, I wonder whether I should start with ActiveMQ
Apache Kafka can be characterized as a "Distributed Streaming Platform" where as ActiveMQ, a MOM, (messaging oriented middleware) is a "General Purpose message broker".
Kafka does one thing, and one thing really well: in a publish/subscribe (pub/sub) architecture, messages are written to topics (logs distributed by partition), which consumers then consume from by offset. Kafka, which is built for the cloud, with very high throughput in mind, focuses on this, and these days is the go-to for asynchronous messaging.
ActiveMQ supports both pub/sub and point-to-point semantics. In the latter, a queue handles single messages between a single producer and a specific consumer. This, like pub/sub, is asynchronous, but works slightly differently: if a consumer gets a message on the queue but fails to acknowledge it, the message is then sent to another consumer. ActiveMQ also supports supports several messaging protocols, including AMQP, STOMP, JMS, CAMEL and MQTT.
While Apache Kafka may be the go-to for simple async communication; ActiveMQ seems to be preferred by some for more complicated routing patterns, like enterprise patterns, however, many argue that Kafka is an improvement over ActiveMQ, for reasons such as higher throughput, more efficient management of partitions for logs/topics, and finer-grained ACLs for consumers consuming a topic.
I amde a performance benchmark of ActiveMQ, Apollo, HornetQ under non persistent scenario and persistent scenario, I think it will helpful for you to choose which one should be used, the link as shown below: http://hiramchirino.com/jms-benchmark/ubuntu-2600k/index.html
Apache ActiveMQ is a great workhorse full of features and nice stuff. It's not the fastest MQ software around but fast enough for most use cases. Among features are flexible clustring, fail-over, integrations with different application servers, security etc.
Apache Apollo is an attempt to write a new core for ActiveMQ to cope with a large amount of clients and messages. It does not have all nice and convenient feature of ActiveMQ but scales a lot better. Apache Apollo is a really fast MQ implementation when you give it a large multi-core server and thousands of concurrent connections. It has a nice, simple UI, but is not a "one-size-fits-all" solution.
It seems that there is an attempt ongoing to merge a number of ActiveMQ features with HornetQ under the name ActiveMQ Artemis. HornetQ has JMS2.0 support, so my humble guess is that it's likely to appear in ActiveMQ 6.x.
JIRA, Github
Kafka is a different beast. It's a very simple message broker intended to scale persistent publish subscribe (topics) as fast as possible over multiple servers. For small-medium sized deployments, Kafka is probably not the best option. It also has it's way to do things to achieve the high throughput, so you have to trade a lot in terms of flexibility to get high distributed throughput. If you are new to the area of MQ and brokers, I guess Kafka is overkill. On the other hand - if you have a decent sized server cluster and wonder how to push as many messages as possible through it - give Kafka a spin!
This is an older question but I'll provide a more modern answer here.
EDIT: The 2.3.0 Apache Artemis release happened ~Sept 5 2017. So it does seem to be progressing as of now. But (link) changelog still seems too scary.