________________________________ From: Bruno Freudensprung <[email protected]> Sent: Tuesday, January 16, 2018 7:54 AM To: [email protected] Subject: Observers: a link to message bus?
Hi, I have a question regarding this part of the Observers Guide (https://zookeeper.apache.org/doc/r3.4.11/zookeeperObservers.html): ZooKeeper Observers<https://zookeeper.apache.org/doc/r3.4.11/zookeeperObservers.html> zookeeper.apache.org Setting up a ZooKeeper ensemble that uses Observers is very simple, and requires just two changes to your config files. Firstly, in the config file of every node ... "As a link to a message bus : [...] Observers would give a natural integration point for this work: a plug-in mechanism could be used to attach the stream of proposals an Observer sees to a publish-subscribe system" I've not been able to find such a plug-in mechanism in the source code of ZooKeeper. For the moment the only integration point I can think of is the commitRequest method of the org.apache.zookeeper.server.quorum.ObserverZooKeeperServer class. Am I looking in the right direction? To be honest: this is for the moment only pure curiosity since Apache Kafka seems to be a more "natural" and out-of-the-box option for an ordered message bus. However since I might probably need ZooKeeper for its distributed lock and leader election features, I was wondering if I could use it as an ordered message bus as well. MG>if ActiveMQ does indeed support ordered messaging for multiple active consumers thru Message Groups as stated: MG>Message Groups which is the way to load balance multiple active consumers listening to the same queue while preserving message order. MG>i have asked why does Zookeeper not support MessageOrderingTechnology such as ActiveMQ as a plugin? MG>have you discovered "plugin integration" within the Zookeeper Architecture? Best regards, Bruno. MG>Thanks Bruno
