[GitHub] [activemq-artemis] brusdev commented on a change in pull request #3634: ARTEMIS-3365 Broker Balancers

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brusdev commented on a change in pull request #3634:
URL: https://github.com/apache/activemq-artemis/pull/3634#discussion_r657449151



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File path: docs/user-manual/en/broker-balancers.md
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+# Broker Balancers
+Apache ActiveMQ Artemis broker balancers allow incoming client connections to be distributed across multiple [target brokers](target-brokers).
+The target brokers are grouped in [pools](#pools) and the broker balancers use a [target key](#target-key)
+to select a target broker from a pool of brokers according to a [policy](#policies).
+
+## Target Broker
+Target broker is a broker that can accept incoming client connections and is local or remote.
+The local target is a special target that represents the same broker hosting the broker balancer.
+The remote target is another broker reachable by the broker that hosts the broker balancer.
+
+## Target Key
+The broker balancer uses a target key to select a target broker.
+It is a string retrieved from an incoming client connections, the supported values are:
+* `SNI_HOST` is the hostname indicated by the client in the SNI extension of the TLS protocol;
+* `SOURCE_IP` is the source IP address of the client;
+* `USER_NAME` is the username indicated by the client.
+
+## Pools
+The pool is a group of brokers and checks periodically their state.
+Including the local target broker in the pool allows broker hosting the broker balancer to accept incoming client connections. 
+By default, a pool doesn't include the local target broker, to include it the `local-target-enabled` parameter must be `true`.
+A pool becomes ready when the minimum number of ready targets defined by the `quorum-size` parameter is reached.
+This behaviour avoids weird distribution at startup or after a restart.

Review comment:
       if the quorum is not reached and the target key is not present in the cache then the connection is rejected




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