HOW TO：設定 N 層式同步處理
此主題示範如何針對 Sync Framework 設定 N 層式同步處理。此主題中的範例將重點放在下列的 Sync Framework 型別：
如需有關如何執行範例程式碼的詳細資訊，請參閱撰寫一般用戶端和伺服器同步處理工作中的＜HOW-TO 主題中的範例應用程式＞。
了解 N 層式同步處理
在 N 層式同步處理架構中，同步處理元件會分佈在多層之間，如下圖所示。
.gif "N 層式同步處理的拓撲")
在兩層式架構中，所有元件都位於用戶端上，而且用戶端會直接與伺服器進行通訊。在 N 層式架構中，伺服器同步處理提供者位於伺服器或另一個層，而且各層之間的通訊是由 ServerSyncProviderProxy 物件和 Windows Communication Foundation (WCF) 等服務所處理。Sync Framework 的其中一項優點是，您可以輕鬆地將程式碼從某個兩層式架構移至 N 層式架構。如果程式碼的建構方式正確，在您建立服務並加入 Proxy 之後，只需要對同步代理程式的程式碼進行小幅變更即可。用戶端和伺服器同步處理提供者則不需要進行變更。
範例
下列程式碼範例將說明 N 層式架構中所包含的主要元件。其他 WCF 元件是必要元件。如果您使用 Visual Studio 2008，就會為您產生這些元件。如需詳細資訊，請參閱 Visual Studio 文件。
API 的主要部分
本節提供一些程式碼範例，其中會示範兩層式和 N 層式同步處理之間的相似性，並指出當您設定 N 層式同步處理時可使用之 API 的重要部分。下列程式碼範例來自衍生自 SyncAgent 的類別 (Class)。若為兩層式同步處理，用戶端提供者與伺服器提供者會直接在同步代理程式中當做本機和遠端提供者參考。
this.LocalProvider = new SampleClientSyncProvider();
this.RemoteProvider = new SampleServerSyncProvider();
Me.LocalProvider = New SampleClientSyncProvider()
Me.RemoteProvider = New SampleServerSyncProvider()
下列程式碼範例會直接參考用戶端提供者，如兩層式範例所示。不過，遠端提供者現在會參考 Proxy，而非直接參考伺服器提供者。此 Proxy 的建立方式是藉由傳遞 WCF 服務的參考。
this.LocalProvider = new SampleClientSyncProvider();
ServiceReference.ServiceForSyncClient serviceProxy = new ServiceReference.ServiceForSyncClient();
this.RemoteProvider = new ServerSyncProviderProxy(serviceProxy);
Me.LocalProvider = New SampleClientSyncProvider()
Dim serviceProxy As New ServiceReference.ServiceForSyncClient()
Me.RemoteProvider = New ServerSyncProviderProxy(serviceProxy)
下列程式碼範例會建立用戶端和伺服器提供者。不論使用兩層式或 N 層式架構，這個程式碼都完全相同。
public class SampleClientSyncProvider : SqlCeClientSyncProvider
{
public SampleClientSyncProvider()
{
//Specify a connection string for the sample client database.
Utility util = new Utility();
this.ConnectionString = util.ClientConnString;
}
}
public class SampleServerSyncProvider : DbServerSyncProvider
{
public SampleServerSyncProvider()
{
//Create a connection to the sample server database.
Utility util = new Utility();
SqlConnection serverConn = new SqlConnection(util.ServerConnString);
this.Connection = serverConn;
//Create a command to retrieve a new anchor value from
//the server.
SqlCommand selectNewAnchorCommand = new SqlCommand();
string newAnchorVariable = "@" + SyncSession.SyncNewReceivedAnchor;
selectNewAnchorCommand.CommandText = "SELECT " + newAnchorVariable + " = min_active_rowversion() - 1";
selectNewAnchorCommand.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp);
selectNewAnchorCommand.Parameters[newAnchorVariable].Direction = ParameterDirection.Output;
selectNewAnchorCommand.Connection = serverConn;
this.SelectNewAnchorCommand = selectNewAnchorCommand;
//Create a SyncAdapter for the Customer table manually, or
//by using the SqlSyncAdapterBuilder as in the following
//code.
SqlSyncAdapterBuilder customerBuilder = new SqlSyncAdapterBuilder(serverConn);
customerBuilder.TableName = "Sales.Customer";
customerBuilder.TombstoneTableName = customerBuilder.TableName + "_Tombstone";
customerBuilder.SyncDirection = SyncDirection.DownloadOnly;
customerBuilder.CreationTrackingColumn = "InsertTimestamp";
customerBuilder.UpdateTrackingColumn = "UpdateTimestamp";
customerBuilder.DeletionTrackingColumn = "DeleteTimestamp";
SyncAdapter customerSyncAdapter = customerBuilder.ToSyncAdapter();
customerSyncAdapter.TableName = "Customer";
this.SyncAdapters.Add(customerSyncAdapter);
}
}
Public Class SampleClientSyncProvider
Inherits SqlCeClientSyncProvider
Public Sub New()
'Specify a connection string for the sample client database.
Dim util As New Utility()
Me.ConnectionString = util.ClientConnString
End Sub
End Class
Public Class SampleServerSyncProvider
Inherits DbServerSyncProvider
Public Sub New()
'Create a connection to the sample server database.
Dim util As New Utility()
Dim serverConn As New SqlConnection(util.ServerConnString)
Me.Connection = serverConn
'Create a command to retrieve a new anchor value from
'the server.
Dim selectNewAnchorCommand As New SqlCommand()
Dim newAnchorVariable As String = "@" + SyncSession.SyncNewReceivedAnchor
selectNewAnchorCommand.CommandText = "SELECT " + newAnchorVariable + " = min_active_rowversion() 1"
selectNewAnchorCommand.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp)
selectNewAnchorCommand.Parameters(newAnchorVariable).Direction = ParameterDirection.Output
selectNewAnchorCommand.Connection = serverConn
Me.SelectNewAnchorCommand = selectNewAnchorCommand
'Create a SyncAdapter for the Customer table manually, or
'by using the SqlSyncAdapterBuilder as in the following
'code.
Dim customerBuilder As New SqlSyncAdapterBuilder(serverConn)
customerBuilder.TableName = "Sales.Customer"
customerBuilder.TombstoneTableName = customerBuilder.TableName + "_Tombstone"
customerBuilder.SyncDirection = SyncDirection.DownloadOnly
customerBuilder.CreationTrackingColumn = "InsertTimestamp"
customerBuilder.UpdateTrackingColumn = "UpdateTimestamp"
customerBuilder.DeletionTrackingColumn = "DeleteTimestamp"
Dim customerSyncAdapter As SyncAdapter = customerBuilder.ToSyncAdapter()
customerSyncAdapter.TableName = "Customer"
Me.SyncAdapters.Add(customerSyncAdapter)
End Sub
End Class
下列程式碼範例會建立此服務所實作的介面。此介面包含伺服器提供者的四個重要方法。
[ServiceContract]
public interface IServiceForSync
{
[OperationContract()]
SyncContext ApplyChanges(SyncGroupMetadata groupMetadata, DataSet dataSet, SyncSession syncSession);
[OperationContract()]
SyncContext GetChanges(SyncGroupMetadata groupMetadata, SyncSession syncSession);
[OperationContract()]
SyncSchema GetSchema(Collection<string> tableNames, SyncSession syncSession);
[OperationContract()]
SyncServerInfo GetServerInfo(SyncSession syncSession);
}
<ServiceContract()> _
Public Interface IServiceForSync
<OperationContract()> _
Function ApplyChanges(ByVal groupMetadata As SyncGroupMetadata, ByVal dataSet As DataSet, ByVal syncSession As SyncSession) As SyncContext
<OperationContract()> _
Function GetChanges(ByVal groupMetadata As SyncGroupMetadata, ByVal syncSession As SyncSession) As SyncContext
<OperationContract()> _
Function GetSchema(ByVal tableNames As Collection(Of String), ByVal syncSession As SyncSession) As SyncSchema
<OperationContract()> _
Function GetServerInfo(ByVal syncSession As SyncSession) As SyncServerInfo
End Interface
下列程式碼範例會建立一項服務。此服務會實作在上一個程式碼範例中建立的介面，並參考伺服器提供者。
public class ServiceForSync : IServiceForSync
{
private SampleServerSyncProvider _serverSyncProvider;
public ServiceForSync()
{
this._serverSyncProvider = new SampleServerSyncProvider();
}
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
public virtual SyncContext ApplyChanges(SyncGroupMetadata groupMetadata, DataSet dataSet, SyncSession syncSession) {
return this._serverSyncProvider.ApplyChanges(groupMetadata, dataSet, syncSession);
}
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
public virtual SyncContext GetChanges(SyncGroupMetadata groupMetadata, SyncSession syncSession) {
return this._serverSyncProvider.GetChanges(groupMetadata, syncSession);
}
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
public virtual SyncSchema GetSchema(Collection<string> tableNames, SyncSession syncSession) {
return this._serverSyncProvider.GetSchema(tableNames, syncSession);
}
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
public virtual SyncServerInfo GetServerInfo(SyncSession syncSession) {
return this._serverSyncProvider.GetServerInfo(syncSession);
}
}
Public Class ServiceForSync
Implements IServiceForSync
Private _serverSyncProvider As SampleServerSyncProvider
Public Sub New()
Me._serverSyncProvider = New SampleServerSyncProvider()
End Sub
<System.Diagnostics.DebuggerNonUserCodeAttribute()> _
Public Overridable Function ApplyChanges(ByVal groupMetadata As SyncGroupMetadata, ByVal dataSet As DataSet, ByVal syncSession As SyncSession) As SyncContext
Return Me._serverSyncProvider.ApplyChanges(groupMetadata, dataSet, syncSession)
End Function
<System.Diagnostics.DebuggerNonUserCodeAttribute()> _
Public Overridable Function GetChanges(ByVal groupMetadata As SyncGroupMetadata, ByVal syncSession As SyncSession) As SyncContext
Return Me._serverSyncProvider.GetChanges(groupMetadata, syncSession)
End Function
<System.Diagnostics.DebuggerNonUserCodeAttribute()> _
Public Overridable Function GetSchema(ByVal tableNames As Collection(Of String), ByVal syncSession As SyncSession) As SyncSchema
Return Me._serverSyncProvider.GetSchema(tableNames, syncSession)
End Function
<System.Diagnostics.DebuggerNonUserCodeAttribute()> _
Public Overridable Function GetServerInfo(ByVal syncSession As SyncSession) As SyncServerInfo
Return Me._serverSyncProvider.GetServerInfo(syncSession)
End Function
End Class