Blackberry has an HTTP push feature for sending messages to occasionally connected devices. For Blackberry devices paired with BlackBerry Enterprise Server (BES), the HTTP push gateway contains an address that points to the HTTP listener of the BES server. The POST to the BES server has a query parameter that contains the device ID of the target devices (for example, 2100000a for an emulator). The BES server holds the message for a configurable amount of time, and delivers it to the device when the device becomes reachable.
The push listener runs in the background, and listens for server-initiated synchronization notifications, for example, based on a schedule or triggered by a Data Change Notification (DCN):
The HTTP push gateway can also be used for network-connected Sybase Unwired Platform applications (for example the Java desktop). The address of the subscription contains an HTTP URL to an HTTP listener which the application creates. The URL contains a query parameter such as:
&mode=direct
When the HTTP push gateway sees a query parameter without a device ID, the gateway understands that the message is not going through the BES server. For the mode=direct notifications to work, the application must be running and have the listener open. If the application is not running, the HTTPPush gateway reports a ConnectionRefused error in the log files, and the notification is not delivered.