Apache RocketMQ 
Apache RocketMQ is a distributed messaging and streaming platform with low latency, high performance and reliability, trillion-level capacity and flexible scalability.
It offers a variety of features:
- Pub/Sub messaging model
- Financial grade transactional message
- A variety of cross language clients, such as Java, C/C++, Python, Go
- Pluggable transport protocols, such as TCP, SSL, AIO
- Inbuilt message tracing capability, also support opentracing
- Versatile big-data and streaming ecosytem integration
- Message retroactivity by time or offset
- Reliable FIFO and strict ordered messaging in the same queue
- Efficient pull&push consumption model
- Million-level message accumulation capacity in a single queue
- Multiple messaging protocols like JMS and OpenMessaging
- Flexible distributed scale-out deployment architecture
- Lightning-fast batch message exchange system
- Various message filter mechanics such as SQL and Tag
- Docker images for isolated testing and cloud isolated clusters
- Feature-rich administrative dashboard for configuration, metrics and monitoring
- Authentication and authorisation
Learn it & Contact us
- Mailing Lists: https://rocketmq.apache.org/about/contact/
- Home: https://rocketmq.apache.org
- Docs: https://rocketmq.apache.org/docs/quick-start/
- Issues: https://github.com/apache/rocketmq/issues
- Rips: https://github.com/apache/rocketmq/wiki/RocketMQ-Improvement-Proposal
- Ask: https://stackoverflow.com/questions/tagged/rocketmq
- Slack: https://rocketmq-invite-automation.herokuapp.com/
Apache RocketMQ Community
Contributing
We always welcome new contributions, whether for trivial cleanups, big new features or other material rewards, more details see here.
License
Apache License, Version 2.0 Copyright (C) Apache Software Foundation
Export Control Notice
This distribution includes cryptographic software. The country in which you currently reside may have restrictions on the import, possession, use, and/or re-export to another country, of encryption software. BEFORE using any encryption software, please check your country's laws, regulations and policies concerning the import, possession, or use, and re-export of encryption software, to see if this is permitted. See http://www.wassenaar.org/ for more information.
The U.S. Government Department of Commerce, Bureau of Industry and Security (BIS), has classified this software as Export Commodity Control Number (ECCN) 5D002.C.1, which includes information security software using or performing cryptographic functions with asymmetric algorithms. The form and manner of this Apache Software Foundation distribution makes it eligible for export under the License Exception ENC Technology Software Unrestricted (TSU) exception (see the BIS Export Administration Regulations, Section 740.13) for both object code and source code.
The following provides more details on the included cryptographic software:
This software uses Apache Commons Crypto (https://commons.apache.org/proper/commons-crypto/) to support authentication, and encryption and decryption of data sent across the network between services.