Managing Disconnection

The HAClient class, included with the AMPS Python client, contains a disconnect handler and other features for building highly-available applications. The HAClient includes features for managing a list of failover servers, resuming subscriptions, republishing in-flight messages, and other functionality that is commonly needed for high availability. 60East recommends using the HAClient for automatic reconnection wherever possible, as the HAClient disconnect handler has been carefully crafted to handle a wide variety of edge cases and potential failures.

If an application needs to reconnect or fail over, use an HAClient, and the AMPS client library will automatically handle failover and reconnection. You control which servers the client fails over to using an implementation of the ServerChooser interface, and you can control the timing of the failover using an implementation of the ReconnectDelayStrategy interface.

For most applications, the combination of the HAClient disconnect handler and a ConnectionStateListener gives you the ability to monitor disconnections and add custom behavior at the appropriate point in the reconnection process.

If you need to add custom behavior to the failover (such as logging, resetting an internal cache, refreshing credentials and so on), the ConnectionStateListener class allows your application to be notified and take action when disconnection is detected and at each stage of the reconnection process.

To extend the behavior of the AMPS client during reconnection, implement a ConnectionStateListener as described in the section on Monitoring Connection State.