Manage Queue Transfers

AMPS provides actions to enable and disable the "proxied transfer" setting for message queues. As described in the Failover and Queue Message Ownership section of the Replicating Messages Between Instances chapter of the AMPS User Guide, this setting allows an instance to manage ownership of a queue message that is owned by an instance that is offline (or otherwise unreachable from this instance). 60East recommends that these actions only be configured in situations where the administrative interface is unavailable. Unlike most other settings for which actions are provided, the "proxied transfer" setting is intended for disaster recovery rather than normal maintenance.

The amps-action-do-enable-proxied-transfer action can be used to enable proxied transfer for a queue. The amps-action-do-disable-proxied-transfer action can be used to disable proxied transfer for a queue.

Enabling proxied transfer will allow this instance to take ownership of messages owned by an unreachable instance, allowing those messages to be delivered. However, it also introduces the risk of duplicate delivery and duplicate processing in cases where the instance that currently owns the message is still online (but the replication network connection has failed), or in cases where the instance that currently owns the message becomes available again and begins servicing requests. See the Failover and Queue Message Ownership section for more details.

Although an action is provided for flexibility, 60East does not recommend that the enable_proxied_transfer setting is enabled automatically, due to the possibility of duplicate delivery. Instead, this action should be configured to run in response to action by an administrator, after the administrator determines that one of the instances that contains the queue is, in fact, offline and that the possibility of duplicate processing is an acceptable risk.

These actions are intended to assist in maintaining message delivery from a distributed queue during an outage of one of the instances that services the queue. When this setting is enabled, the possibility of duplicate delivery exists.

These actions require the following parameters:

Parameter	Description
Topic (required)	The name of the queue topic for which to enable or disable proxied transfer. There is no default value for this parameter.
MessageType (required)	The message type of the topic for which to enable or disable proxied transfer. There is no default value for this parameter.

This module does not add any variables to the AMPS context.