ChangeBatchBase.BeginOrderedGroup Method
Opens an ordered group in the change batch. This group is ordered by item ID.
Namespace: Microsoft.Synchronization
Assembly: Microsoft.Synchronization (in Microsoft.Synchronization.dll)
Syntax
'Declaration
Public Sub BeginOrderedGroup ( _
itemId As SyncId _
)
'Usage
Dim instance As ChangeBatchBase
Dim itemId As SyncId
instance.BeginOrderedGroup(itemId)
public void BeginOrderedGroup(
SyncId itemId
)
public:
void BeginOrderedGroup(
SyncId^ itemId
)
member BeginOrderedGroup :
itemId:SyncId -> unit
public function BeginOrderedGroup(
itemId : SyncId
)
Parameters
- itemId
Type: Microsoft.Synchronization.SyncId
The closed lower bound of item IDs for this ordered group. To specify a lower bound of 0, use Zero.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | itemId is a null reference (Nothing in Visual Basic). |
| ObjectDisposedException | This ChangeBatch has already been disposed. |
| SyncInvalidOperationException | The change batch contains a group that was started but not ended. |
| ChangeBatchIsReadOnlyException | The change batch has already been sent to a change applier or synchronization session. Changes cannot be added to the batch after it has been sent. |
Remarks
Item changes that are added to the change batch after this method is called are added to the open group.
Item changes cannot be added to the change batch until a group is opened.
Examples
The following example implements GetChangeBatch by adding items to an ordered group in a change batch. An item is only added when its change version is not contained in the destination knowledge.
Public Overrides Function GetChangeBatch(ByVal batchSize As UInteger, ByVal destinationKnowledge As SyncKnowledge) As ChangeBatch
' The destination knowledge must be converted to be compatible with the source replica
' before it can be used.
Dim mappedDestKnowledge As SyncKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge)
' Create a new change batch, initialized by using the current knowledge of the source replica
' and a new ForgottenKnowledge object.
Dim changeBatch As New ChangeBatch(IdFormats, GetKnowledge(), New ForgottenKnowledge())
' Start a group of changes in the change batch. The group is ordered by item ID.
' _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
' position in the metadata store for subsequent calls to GetChangeBatch.
changeBatch.BeginOrderedGroup(_items.Values(_getChangeBatchCurrent).GlobalId)
' itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
' is greater than the requested batch size, enumeration stops and the change batch is returned.
Dim itemsAdded As Integer = 0
Dim itemMeta As ItemMetadata
' Enumerate items and add a change to the change batch if it is not contained in the
' destination knowledge.
' _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
While itemsAdded <= batchSize AndAlso _getChangeBatchCurrent < _items.Count
itemMeta = _items.Values(_getChangeBatchCurrent)
Dim kind As ChangeKind = If((itemMeta.IsDeleted), ChangeKind.Deleted, ChangeKind.Update)
Dim change As New ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion, itemMeta.ChangeVersion)
' If the change is not contained in the destination knowledge, add it to the change batch.
If Not mappedDestKnowledge.Contains(change) Then
changeBatch.AddChange(change)
itemsAdded += 1
End If
_getChangeBatchCurrent += 1
End While
' End the group of changes in the change batch. Pass the current source knowledge.
changeBatch.EndOrderedGroup(_items.Values(_getChangeBatchCurrent - 1).GlobalId, _knowledge)
' When all items in the metadata store have been enumerated, set this batch as the
' last batch.
If _getChangeBatchCurrent = _items.Count Then
changeBatch.SetLastBatch()
End If
Return changeBatch
End Function
public override ChangeBatch GetChangeBatch(uint batchSize, SyncKnowledge destinationKnowledge)
{
// The destination knowledge must be converted to be compatible with the source replica
// before it can be used.
SyncKnowledge mappedDestKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge);
// Create a new change batch, initialized by using the current knowledge of the source replica
// and a new ForgottenKnowledge object.
ChangeBatch changeBatch = new ChangeBatch(IdFormats, GetKnowledge(), new ForgottenKnowledge());
// Start a group of changes in the change batch. The group is ordered by item ID.
// _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
// position in the metadata store for subsequent calls to GetChangeBatch.
changeBatch.BeginOrderedGroup(_items.Values[_getChangeBatchCurrent].GlobalId);
// itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
// is greater than the requested batch size, enumeration stops and the change batch is returned.
int itemsAdded = 0;
ItemMetadata itemMeta;
// Enumerate items and add a change to the change batch if it is not contained in the
// destination knowledge.
// _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
for (; itemsAdded <= batchSize && _getChangeBatchCurrent < _items.Count; _getChangeBatchCurrent++)
{
itemMeta = _items.Values[_getChangeBatchCurrent];
ChangeKind kind = (itemMeta.IsDeleted) ? ChangeKind.Deleted : ChangeKind.Update;
ItemChange change = new ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion,
itemMeta.ChangeVersion);
// If the change is not contained in the destination knowledge, add it to the change batch.
if (!mappedDestKnowledge.Contains(change))
{
changeBatch.AddChange(change);
itemsAdded++;
}
}
// End the group of changes in the change batch. Pass the current source knowledge.
changeBatch.EndOrderedGroup(_items.Values[_getChangeBatchCurrent - 1].GlobalId, _knowledge);
// When all items in the metadata store have been enumerated, set this batch as the
// last batch.
if (_getChangeBatchCurrent == _items.Count)
{
changeBatch.SetLastBatch();
}
return changeBatch;
}