ISimpleSyncProviderConcurrencyConflictResolver Interface

Represents a custom conflict resolver that handles concurrency conflicts, such as the same item being updated at the local replica and deleted at the remote replica.

Namespace: Microsoft.Synchronization.SimpleProviders
Assembly: Microsoft.Synchronization.SimpleProviders (in microsoft.synchronization.simpleproviders.dll)

Syntax

'Declaration
Public Interface ISimpleSyncProviderConcurrencyConflictResolver
'Usage
Dim instance As ISimpleSyncProviderConcurrencyConflictResolver

public interface ISimpleSyncProviderConcurrencyConflictResolver

public interface class ISimpleSyncProviderConcurrencyConflictResolver

public interface ISimpleSyncProviderConcurrencyConflictResolver

public interface ISimpleSyncProviderConcurrencyConflictResolver

Remarks

For more information about concurrency conflicts, see Handling Conflicts for Simple Providers.

Example

In this example, the conflict handling policies for concurrency conflicts and constraint conflicts are left as the default of ApplicationDefined. This means that the application will register for the ItemConflicting and ItemConstraint events and specify an action to resolve conflicts if they occur during synchronization processing. For more information, see Handling Conflicts for Simple Providers. To view this code in the context of a complete application, see the "Sync101 using Simple Sync Provider" application that is available in the Sync Framework SDK and from Code Gallery. The following code example shows the event handlers that are specified in the constructor of MyFullEnumerationSimpleSyncProvider.

this.ItemConstraint += new EventHandler<SimpleSyncItemConstraintEventArgs>(OnItemConstraint);
this.ItemConflicting += new EventHandler<SimpleSyncItemConflictingEventArgs>(OnItemConflicting);

AddHandler Me.ItemConstraint, AddressOf HandleItemConstraint

The following code example shows the event handlers setting the conflict resolution actions to Merge.

void OnItemConstraint(object sender, SimpleSyncItemConstraintEventArgs e)
{
    // Set the resolution action for constraint conflicts.
    // In this sample, the provider checks for duplicates in InsertItem, and this event would
    // fire if a duplicate occurred. 
    e.SetResolutionAction(ConstraintConflictResolutionAction.Merge);
}

void OnItemConflicting(object sender, SimpleSyncItemConflictingEventArgs e)
{
    // Set the resolution action for concurrency conflicts.
    e.SetResolutionAction(ConflictResolutionAction.Merge);
}

Private Sub HandleItemConstraint(ByVal sender As Object, ByVal e As SimpleSyncItemConstraintEventArgs)
    ' Set the resolution action for constraint conflicts. 
    ' In this sample, the provider checks for duplicates in InsertItem, and this event would 
    ' fire if a duplicate occurred. 
    e.SetResolutionAction(ConstraintConflictResolutionAction.Merge)
End Sub

Private Sub HandleItemConflicting(ByVal sender As Object, ByVal e As SimpleSyncItemConflictingEventArgs)
    ' Set the resolution action for concurrency conflicts. 
    e.SetResolutionAction(ConflictResolutionAction.Merge)
End Sub

The following code example shows the ResolveUpdateUpdateConflict method that is implemented to respond to a resolution action of Merge for a concurrency conflict:

public void ResolveUpdateUpdateConflict(object itemData, 
    IEnumerable<SyncId> changeUnitsToMerge, 
    IEnumerable<SyncId> changeUnitsToUpdate, 
    ItemFieldDictionary keyAndExpectedVersion, 
    RecoverableErrorReportingContext recoverableErrorReportingContext, 
    out ItemFieldDictionary updatedVersion)
{
    ItemTransfer transfer = (ItemTransfer)itemData;
    ItemData dataCopy = new ItemData(transfer.ItemData);

    // Combine the conflicting data.
    ItemData mergedData = (_store.Get(transfer.Id)).Merge((ItemData)dataCopy);
    ulong timeStamp = _store.UpdateItem(transfer.Id, mergedData);

    updatedVersion = new ItemFieldDictionary();
    updatedVersion.Add(new ItemField(CUSTOM_FIELD_TIMESTAMP, typeof(ulong), timeStamp));
}

Public Sub ResolveUpdateUpdateConflict(ByVal itemData As Object, ByVal changeUnitsToMerge As IEnumerable(Of SyncId), ByVal changeUnitsToUpdate As IEnumerable(Of SyncId), ByVal keyAndExpectedVersion As ItemFieldDictionary, ByVal recoverableErrorReportingContext As RecoverableErrorReportingContext, _
    ByRef updatedVersion As ItemFieldDictionary) Implements ISimpleSyncProviderConcurrencyConflictResolver.ResolveUpdateUpdateConflict
    Dim transfer As ItemTransfer = DirectCast(itemData, ItemTransfer)
    Dim dataCopy As New ItemData(transfer.ItemData)

    ' Combine the conflicting data. 
    Dim mergedData As ItemData = (_store.[Get](transfer.Id)).Merge(DirectCast(dataCopy, ItemData))
    Dim timeStamp As ULong = _store.UpdateItem(transfer.Id, mergedData)

    updatedVersion = New ItemFieldDictionary()
    updatedVersion.Add(New ItemField(CUSTOM_FIELD_TIMESTAMP, GetType(ULong), timeStamp))
End Sub

See Also

Reference

ISimpleSyncProviderConcurrencyConflictResolver Members
Microsoft.Synchronization.SimpleProviders Namespace