Data change notifications (DCNs) notify Unwired Server when data used by an application changes on an EIS server.
Developers typically use DCNs because they:
- Avoid the need to repopulate all the data in the mobile business object cache data every time data changes in the back-end EIS system.
-
Allow the Unwired Server cache to be updated in real time by the EIS server, rather than administrator configured schedule.
DCNs are typically used in combination with a sychronization group. Part of the synchronization group is a change detection interval property. For messaging based sync applications, the property is used to send a "data change" message to the messaging based sync clients that subscribe to that data. Replication-based sync applications requires a subscription and the configuration of a device push notifications which then notifies the mobile clients.
DCNs and either data change messages or device notifications address these concerns:
- Users do not always know when to synchronize. Waiting for a user-triggered synchronization is unreliable.
- Using server-triggered push synchronization is reliable, but frequent synchronizations (for example, every X minutes) generates high traffic volumes for Unwired Server.
- Data consistency between the source EIS data and Unwired Server cache is limited to what administrators typically configure for a cache refresh interval for the entire system. It does not give priority to time-critical data.
You can configure either secure (HTTPS) or non-secure (HTTP) for DCNs. For details on how DCNs are created and sent see the Developer Guide: Unwired Server.