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After considering a few approaches, listed in Rejected Alternatives (not really rejected, up for discussion) section, below is what we think is the least obtrusive approach to support namespaces in Kafka. We suggest to represent namespaces at storage layer, i.e., storage layout of Zookeeper entities and logs on disk. Internal and public APIs can pass around namespaces, as part of, prepended to, topic names. However, we need to separate namespace and topic while interacting with storage layers. This can be done by using a delimiter that is not allowed in Kafka topics. Currently, Kafka allows a topic name to contain characters only in [a-zA-Z0-9\\._\\-]. That gives us a few options to decide on the delimiting char. We suggest to have ":" as the delimiting char, but it can be any of the following.
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