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SQL Anywhere 11.0.0 » MobiLink - Server-Initiated Synchronization » Introducing server-initiated synchronization


Components of server-initiated synchronization

MobiLink server-initiated synchronization uses the following components:

  • Push requests   cause synchronization to occur. A push request takes the form of some data that you insert into a table on the MobiLink consolidated database, or in some cases data inserted into a temporary table or even just a SQL result set. You can create push requests in any way that you cause data to be inserted into a table. For example, a push request could be created by a database trigger that is activated when a price changes. Any database application can create push requests, including the Notifier. See Push requests.

  • The Notifier   is a program running on the same computer as the MobiLink server. It polls the consolidated database on a regular basis, looking for push requests. You control how often the Notifier polls the database. You specify business logic that the Notifier uses to gather push requests, including which remote devices should be notified. When the Notifier detects a request, it sends the message associated with the request to a Listener on one or more remote devices. You have the option to send repeatable messages with an expiry time. See Notifiers.

  • The Listener   is a program that is installed on each remote device. It receives messages from the Notifier and initiates action. The action is usually synchronization, but can be other things. You can configure the Listener to act only on messages from selected sources, or with specific content.

    On Windows or Windows Mobile, the Listener is an executable program configured by command line options. To receive a message, the remote device must be on and the Listener must be started. See Listener utility.

    On the Palm OS, you first create a configuration file by running the Palm Listener Configuration utility on a Windows desktop. You then copy the configuration file to your Palm device and run the Palm Listener. See Listeners for Palm devices.

  • Gateways   provide an interface to send messages from the Notifier to the Listener. You can send messages using a SYNC gateway, a UDP gateway, or an SMTP gateway. The SYNC gateway uses the same protocol as your MobiLink synchronizations.

    • Device tracking gateways   provide a way to automatically track remote devices. Using device tracking functionality, you don't have to know the addresses of remote devices. You supply the gateway name of your device tracker gateway (by default, Default-DeviceTracker) and the MobiLink user name, and MobiLink routes the message through the appropriate gateway to the appropriate device.

    For more information, see Gateways and carriers.