zipkin-collector/activemq/RATIONALE.md
ActiveMQ was formerly requested in April, 2018 through issue #1990 which had two other thumbs-up. An early draft of this implementation was developed by @IAMTJW and resulting in another user asking for it. In June of 2019 there were a couple more requests for this on gitter, notably about Amazon MQ.
All users who expressed interest were interestd in ActiveMQ 5.x (aka Classic), not Artemis. Moreover, at the time of creation Amazon MQ only supported ActiveMQ 5.x.
Artemis has higher throughput potential, but has more conflicting dependencies and would add 8MiB to the server. Moreover, no-one has asked for it.
ActiveMQ's client is 2MiB, which will increase the jar size, something that we've been tracking
recently. To be fair, this is not a large module. In comparison, one dependency of Kafka, zstd-jni
alone is almost 4MiB. There are no dependencies likely to conflict at runtime, and only one dodgy
dependency, hawtbuf, on account of it being abandoned since
2014.
Apart from size, ActiveMQ is a stable integration, included in Spring Boot, and could be useful for other integrations as an in-memory queue. Moreover, bundling makes integration with zipkin-aws far easier in the same way as bundling elasticsearch does.
This package is using the normal activemq-jms client. During a mail thread, we learned the the STOMP and AMQP 1.0 protocol are the more portable options for a portable integration as ActiveMQ, Artemis and RabbitMQ all support these. On the other hand Kafka does not support these protocols. Any future portability work could be limited by this. Meanwhile, using the standard JMS client will make troubleshooting most natural to end users.