You implement a synchronous listener notification class by extending com.wm.adk.notification.WmSyncListenerNotification. (Examples in this section do not implement a synchronous notification, so the figure in this section only shows a placeholder class.) Unlike the other types of notifications discussed in this document, a synchronous notification does not call doNotify to publish a document. Instead, it calls the WmSynchronousNotification.invokeService method, passing it a WmRecord containing data consistent with the output signature of the notification node.

Synchronous notifications are expected to define both an input and output signature. The terms input and output are relative to the notification. The output signature specifies the format of the data that the notification places on the pipeline prior to invoking the service associated with the synchronous notification. The input signature describes the data that the notification expects to find on the pipeline after the invoked service has completed processing.

The service to be invoked by WmSynchronousNotification.invokeService is specified at design time in the notification node data. When this service is invoked, it executes on a separate thread (and therefore in a different transactional context) from the listener. When the invoked service completes, the server will extract any data on the pipeline that is identified in the notification node's input signature and will deliver that data as a WmRecord wrapped in the SyncNotificationResults object returned by invokeService.