When working with distributed data applications, there are often times when clients try to make data changes that conflict with changes that were already made. The following scenarios are core cases where data synchronization conflicts occur:

The following example shows a simple event handler that displays an Alert box on the client where a conflict occurs, and accepts the server version of the data:

...
public function useDS:void {
...

    ds.addEventListener(DataConflictEvent.CONFLICT, conflictHandler);        
...
}

public function conflictHandler(event:DataConflictEvent):void {
    var conflicts:Conflicts = ds.conflicts;
    var c:Conflict;
    for (var i:int=0; i<conflicts.length; i++) {
        c = Conflict(conflicts.getItemAt(i));
        Alert.show("Reverting to server value", "Conflict");
        c.acceptServer();
    }
}

For more information about the mx.data.Conflicts and mx.data.Conflict, and mx.data.events.DataConflictEvent classes, see the Adobe LiveCycle ES ActionScript Reference.

When you use the Java adapter with a custom assembler, you can write logic in your assembler class that handles data synchronization and throws a DataSyncException if the previous version of the data does not match what is currently in the data resource. A DataSyncException results in a DataConflictEvent on the client. For more information, see Custom assemblers.

You can also let the user decide which version of data gets used when a conflict occurs, as the following code snippets show. PersonForm represents a custom component that displays all of the properties of the Person object assigned to its dataSource property.

// Conflict event handler:
function resolveConflictsHandler():void {
displayConflictsScreen();
}
...
<!-- Conflicts screen MXML code: -->
<PersonForm id="serverValue" editable="false" dataSource="{ds.conflicts.current.serverObject}"/> 

<PersonForm id="clientValue" dataSource="{ds.conflicts.current.clientObject}"/>

<PersonForm id="originalValue" dataSource="{ds.conflicts.current.originalObject}" editable="false"/>

<mx:Button label="Accept Server" click="ds.conflicts.current.acceptServer()"/>
<mx:Button label="Accept Client" click="ds.conflicts.current.acceptClient()"/>
...