Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide

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## Load-Balanced Message Inflow

Application Server delivers messages randomly to MDBs having same `ClientID` . The `ClientID` is required for durable subscribers.

For non-durable subscribers in which the `ClientID` is not configured, all instances of a specific MDB that subscribe to same topic are considered equal. When an MDB is deployed to multiple instances of the Application Server, only one of the MDBs receives the message. If multiple distinct MDBs subscribe to same topic, one instance of each MDB receives a copy of the message.

To support multiple consumers using the same queue, set the `maxNumActiveConsumers` property of the physical destination to a large value. If this property is set, MQ allows up to that number of MDBs to consume messages from same queue. The message is delivered randomly to the MDBs. If `maxNumActiveConsumers` is set to `-1`, there is no limit to the number of consumers.

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