1. A system for automatic migration of poller proxy services in an application server cluster, comprising: one or more computers, each including a microprocessor; an enterprise service bus (ESB) cluster, executing on the one or more computers, wherein the ESB cluster includes a plurality of managed servers, and a poller proxy service, wherein an instance of the poller proxy service is deployed on each of the plurality of managed servers, and wherein a single one of the plurality of managed servers includes a poller engine configured to execute the instance of the poller proxy service on the single managed server; a poller singleton application and a cluster change listener registered therewith, wherein the cluster change listener listens for one or more state changes in the ESB cluster; wherein the poller singleton application operates to receive a notification that the single managed server including the poller engine fails, determine one or more running managed servers in the ESB cluster, and migrate the poller engine from the single managed server that has failed to one of the one or more running managed servers; wherein the migrated poller engine continues to execute the instance of the poller proxy service on the running managed server.