1. At a publishing service that notifies subscribers of events of interest, a method of maintaining connectivity and an active subscription, without requiring dedicated code independent of the publishing service, the method comprising: establishing a heartbeat subscription at a publishing service that notifies a subscriber of a plurality of events, wherein the heartbeat event subscription periodically sends heartbeat event notifications to the subscriber regardless of whether or not one or more other event notifications from the plurality of events are available for sending; sending a first event notification to the subscriber; upon sending the first event notification, monitoring an interval specified by the established heartbeat subscription; and on or before expiration of the interval, the method further comprises at least one of the following, sending a second event notification to the subscriber for indicating that the publishing service application is operational and connectivity exists between the publishing service application and the subscriber application, or receiving a pull request from the subscriber requesting event notifications that have occurred since a previous pull request indicating that connectivity exists between the subscriber application and the publishing service application.