This is described in a bit more detail in a Kafka paper: https://cwiki.apache.org/confluence/display/KAFKA/Kafka+papers+and+presentations
Feel free to ask again if you still have questions after reading the paper. Thanks, Jun On Sun, Apr 15, 2012 at 9:24 PM, samal <samalgo...@gmail.com> wrote: > I am having hard time understanding this. Any src where it is explained ? > > "Each consumer process belongs to a consumer group and each message is > delivered to exactly one process within every consumer group. Hence a > consumer group allows many > processes or machines to logically act as a single consumer. The concept of > consumer group is very powerful > and can be used to support the semantics of either a queue or topic as > found in JMS. To support queue > semantics, we can put all consumers in a single consumer group, in which > case each message will go to a > single consumer. To support topic semantics, each consumer is put in its > own consumer group, and then all > consumers will receive each message. A more common case in our own usage is > that we have multiple logical > consumer groups, each consisting of a cluster of consuming machines that > act as a logical whole. Kafka has > the added benefit in the case of large data that no matter how many > consumers a topic has, a message is > stored only a single time." > > > /Samal >
