Restricting AMQP client takeover

When an AMQP client connection is made that has the same client identifier as an existing AMQP client connection, the existing client connection is disconnected by default. However, you can configure the queue manager to restrict the client takeover behavior so that takeover is possible only when certain criteria are met.

For example, disconnecting the existing client connection might not be appropriate if there are AMQP applications being developed by different teams and they happen to be using the same client ID. To address this issue you can restrict client takeover based on the name of the AMQP channel being used, the IP address of the client, and client User ID (when SASL authentication is enabled).

Use the settings of queue manager attributes AdoptNewMCA and AdoptNewMCACheck to specify the required level of client takeover restriction, as detailed in the following table:

Table 1. AdoptNewMCA and AdoptNewMCACheck settings to restrict client takeover
AdoptNewMCA	AdoptNewMCACheck	Criteria checked before client takeover is allowed
NO or undefined	Not applicable	None. Client takeover is allowed for all client connections that are authenticated and pass all CHLAUTH rules.
ALL (or value other than NO)	QM or undefined	None. Client takeover is allowed for all client connections that are authenticated and pass all CHLAUTH rules.
ALL (or value other than NO)	NAME	User ID (when SASL enabled) Channel name
ALL (or value other than NO)	ADDRESS	User ID (when SASL enabled) IP address
ALL (or value other than NO)	ALL	User ID (when SASL enabled) Channel name IP address

The queue manager attributes AdoptNewMCA and AdoptNewMCACheck are part of the queue manager configuration, which is defined in the CHANNELS stanza. On IBM® MQ for Windows and IBM MQ for Linux® x86-64 systems, modify configuration information using the MQ Explorer. On other systems, modify the information by editing the qm.ini configuration file. For information about how to modify the queue manager channels information, see Attributes of the channels stanza.