Apache ActiveMQ ™ is the most popular and powerful open source messaging and Integration Patterns server.
Apache ActiveMQ is fast, supports many Cross Language Clients and Protocols, comes with easy to use Enterprise Integration Patterns and many advanced features while fully supporting JMS 1.1 and J2EE 1.4. Apache ActiveMQ is released under the Apache 2.0 License
with activemq we had disk database crashes once a month. activemq did nothing on crash - it still accepted messages and discarded them all.
activemq have poor tooling - there is no way to browse queue or send a message from console, web interface allows to browse queue but is very inconvinient(only limited subset of headers is displayed).
custom binary messaging format(openwire) is simply plain wrong - no interop with third party products, no traceability.
activemq is persistent MQ - this severely affects performance. our deployment was unable to reach even 300messages/second with a queue