In this topic, you will learn how to synchronize a subscription asynchronously by using the SqlCeReplication class. Asynchronous data synchronization lets your application perform other actions while synchronization is occurring. For more information about using the SqlServerCe namespace, see the SqlServerCe namespace reference documentation.
To start asynchronous data synchronization
Initialize a SqlCeReplication object. You must declare the object outside any method so that it can be accessed.
private SqlCeReplication repl;Within the method that begins synchronization, create an instance of the SqlCeReplication object, and then set the necessary properties for synchronization with a Publisher.
this.repl = new SqlCeReplication(); repl.InternetUrl = "https://www.adventure-works.com/sqlmobile/sqlcesa35.dll"; repl.InternetLogin = "MyInternetLogin"; repl.InternetPassword = "<password>"; repl.Publisher = "MyPublisher"; repl.PublisherDatabase = "MyPublisherDatabase"; repl.PublisherLogin = "MyPublisherLogin"; repl.PublisherPassword = "<password>"; repl.Publication = "MyPublication"; repl.Subscriber = "MySubscriber"; repl.SubscriberConnectionString = "Data Source=MyDatabase.sdf";Call the BeginSynchronize method. This returns an IAsyncResult object. When you call BeginSynchronize, you must pass in an AsyncCallback event handler and the SqlCeReplication object. The AsyncCallback event is fired when synchronization is completed. You can also pass in event handlers for the OnStartTableUpload, OnStartTableDownload, and OnSynchronization events.
IAsyncResult ar = repl.BeginSynchronize (new syncCallback(this.SyncCompletedCallback), new OnStartTableUpload(this.OnStartTableUploadCallback), new OnStartTableDownload(this.OnStartTableDownloadCallback), new OnSynchronization(this.OnSynchronizationCallback), repl);
To handle synchronization events:
The only required event is the AsyncCallback, which takes the IAsyncResult as its only parameter.
public void SyncCompletedCallback(IAsyncResult ar) { ... }The OnStartTableUpload and OnStartTableDownload event handlers both take the IAsyncResult and the table name (as a string) as parameters.
public void OnStartTableUploadCallback(IAsyncResult ar, string tableName) { ... } public void OnStartTableDownloadCallback(IAsyncResult ar,string tableName) { ... }The OnSynchronization event handler takes the IAsyncResult and an integer that represents the percent of synchronization that has completed as parameters.
public void OnSynchronizationCallback(IAsyncResult ar, int percentComplete) { ... }
To end asynchronous data synchronization
Within the AsyncCallback event handler, use the passed-in SqlCeReplication object and IAsyncResult object to call the EndSynchronize method.
SqlCeReplication repl = (SqlCeReplication)ar.AsyncState; repl.EndSynchronize(ar);
Example
This example shows how to implement asynchronous data synchronization. In this example, the application uses the SyncStatus to update the user interface during synchronization so that the user knows about the progress. The user interface is updated whenever a synchronization event is fired and every time that a table is uploaded and downloaded. When synchronization is complete, the application obtains the time of the last successful synchronization from the __sysMergeSubscriptions table and displays the results.
public class MyForm : Form
{
private string tableName;
private int percentage;
private SyncStatus eventStatus;
private SqlCeReplication repl;
private EventHandler myUserInterfaceUpdateEvent;
internal enum SyncStatus
{
PercentComplete,
BeginUpload,
BeginDownload,
SyncComplete
}
public MyForm()
{
// InitializeComponent();
this.myUserInterfaceUpdateEvent = new EventHandler(MyUserInterfaceUpdateEvent);
}
public void MyUserInterfaceUpdateEvent(object sender, System.EventArgs e)
{
switch (this.eventStatus)
{
case SyncStatus.BeginUpload:
//this.labelStatusValue.Text = "Began uploading table : " + tableName;
break;
case SyncStatus.PercentComplete:
//this.labelStatusValue.Text = "Sync with SQL Server is " + percentage.ToString() + "% complete.";
break;
case SyncStatus.BeginDownload:
//this.labelStatusValue.Text = "Began downloading table : " + tableName;
break;
case SyncStatus.SyncComplete:
//this.labelStatusValue.Text = "Synchronization has completed successfully";
//this.labelLastSyncValue.Text = GetLastSuccessfulSyncTime().ToString();
break;
}
}
public void SyncCompletedCallback(IAsyncResult ar)
{
try
{
SqlCeReplication repl = (SqlCeReplication)ar.AsyncState;
repl.EndSynchronize(ar);
repl.SaveProperties();
this.eventStatus = SyncStatus.SyncComplete;
}
catch (SqlCeException e)
{
MessageBox.Show(e.Message);
}
finally
{
// NOTE: If you want to set Control properties from within this
// method, you must use Control.Invoke method to marshal
// the call to the UI thread; otherwise you might deadlock your
// application; See Control.Invoke documentation for more information
//
this.Invoke(this.myUserInterfaceUpdateEvent);
}
}
public void OnStartTableUploadCallback(IAsyncResult ar, string tableName)
{
this.tableName = tableName;
this.eventStatus = SyncStatus.BeginUpload;
// NOTE: If you want to set Control properties from within this
// method, you must use Control.Invoke method to marshal
// the call to the UI thread; otherwise you might deadlock your
// application; See Control.Invoke documentation for more information
//
this.Invoke(this.myUserInterfaceUpdateEvent);
}
public void OnSynchronizationCallback(IAsyncResult ar, int percentComplete)
{
this.percentage = percentComplete;
this.eventStatus = SyncStatus.PercentComplete;
// NOTE: If you want to set Control properties from within this
// method, you must use Control.Invoke method to marshal
// the call to the UI thread; otherwise you might deadlock your
// application; See Control.Invoke documentation for more information
//
this.Invoke(this.myUserInterfaceUpdateEvent);
}
public void OnStartTableDownloadCallback(IAsyncResult ar, string tableName)
{
this.tableName = tableName;
this.eventStatus = SyncStatus.BeginDownload;
// NOTE: If you want to set Control properties from within this
// method, you must use Control.Invoke method to marshal
// the call to the UI thread; otherwise you might deadlock your
// application; See Control.Invoke documentation for more information
//
this.Invoke(this.myUserInterfaceUpdateEvent);
}
private void ButtonSynchronize_Click(object sender, System.EventArgs e)
{
try
{
this.repl = new SqlCeReplication();
repl.SubscriberConnectionString = "Data Source=Test.sdf";
if (false == File.Exists("Test.sdf"))
{
repl.AddSubscription(AddOption.CreateDatabase);
repl.PublisherSecurityMode = SecurityType.DBAuthentication;
repl.Publisher = "MyPublisher";
repl.PublisherLogin = "PublisherLogin";
repl.PublisherPassword = "<Password>";
repl.PublisherDatabase = "AdventureWorksDW";
repl.Publication = "AdventureWorksDW";
repl.InternetUrl = "https://www.adventure-works.com/sqlmobile/sqlcesa35.dll";
repl.InternetLogin = "MyInternetLogin";
repl.InternetPassword = "<Password";
repl.Subscriber = "MySubscriber";
}
else
{
repl.LoadProperties();
}
IAsyncResult ar = repl.BeginSynchronize(
new AsyncCallback(this.SyncCompletedCallback),
new OnStartTableUpload(this.OnStartTableUploadCallback),
new OnStartTableDownload(this.OnStartTableDownloadCallback),
new OnSynchronization(this.OnSynchronizationCallback),
repl);
}
catch (SqlCeException ex)
{
MessageBox.Show(ex.Message);
}
}
public DateTime GetLastSuccessfulSyncTime()
{
DateTime localDateTime;
SqlCeConnection conn = null;
SqlCeCommand cmd = null;
try
{
conn = new SqlCeConnection("Data Source = Test.sdf");
conn.Open();
cmd = conn.CreateCommand();
cmd.CommandText = "SELECT LastSuccessfulSync FROM __sysMergeSubscriptions " +
"WHERE Publication=@publication";
cmd.Parameters.Add("@publication", SqlDbType.NVarChar, 4000);
cmd.Parameters["@publication"].Value = "AdventureWorksDW";
//Note: LastSuccessfulSync is stored in local time, not UTC time
localDateTime = (DateTime)cmd.ExecuteScalar();
return localDateTime;
}
finally
{
conn.Close();
}
}
}
Public Class MyForm
Inherits Form
Private myUserInterfaceUpdateEvent As EventHandler
Private tableName As String
Private percentage As Integer
Private eventStatus As SyncStatus
Private repl As SqlCeReplication
Friend Enum SyncStatus
PercentComplete
BeginUpload
BeginDownload
SyncComplete
End Enum 'SyncStatus
Public Sub New()
' InitializeComponent();
Me.myUserInterfaceUpdateEvent = New EventHandler(AddressOf UserInterfaceUpdateEvent)
End Sub 'New
Public Sub UserInterfaceUpdateEvent(ByVal sender As Object, ByVal e As System.EventArgs)
Select Case Me.eventStatus
Case SyncStatus.BeginUpload
'this.labelStatusValue.Text = "Began uploading table : " & tableName;
Case SyncStatus.PercentComplete
'this.labelStatusValue.Text = "Sync with SQL Server is " & percentage.ToString() & "% complete.";
Case SyncStatus.BeginDownload
'this.labelStatusValue.Text = "Began downloading table : " & tableName;
Case SyncStatus.SyncComplete
'this.labelStatusValue.Text = "Synchronization has completed successfully";
'this.labelLastSyncValue.Text = GetLastSuccessfulSyncTime().ToString();
End Select
End Sub 'UserInterfaceUpdateEvent
Public Sub SyncCompletedCallback(ByVal ar As IAsyncResult)
Try
Dim repl As SqlCeReplication = CType(ar.AsyncState, SqlCeReplication)
repl.EndSynchronize(ar)
repl.SaveProperties()
Me.eventStatus = SyncStatus.SyncComplete
Catch e As SqlCeException
MessageBox.Show(e.Message)
Finally
' NOTE: If you want to set Control properties from within this
' method, you must use Control.Invoke method to marshal
' the call to the UI thread; otherwise you might deadlock your
' application; See Control.Invoke documentation for more information
'
Me.Invoke(Me.myUserInterfaceUpdateEvent)
End Try
End Sub 'SyncCompletedCallback
Public Sub OnStartTableUploadCallback(ByVal ar As IAsyncResult, ByVal tableName As String)
Me.tableName = tableName
Me.eventStatus = SyncStatus.BeginUpload
' NOTE: If you want to set Control properties from within this
' method, you must use Control.Invoke method to marshal
' the call to the UI thread; otherwise you might deadlock your
' application; See Control.Invoke documentation for more information
'
Me.Invoke(Me.myUserInterfaceUpdateEvent)
End Sub 'OnStartTableUploadCallback
Public Sub OnSynchronizationCallback(ByVal ar As IAsyncResult, ByVal percentComplete As Integer)
Me.percentage = percentComplete
Me.eventStatus = SyncStatus.PercentComplete
' NOTE: If you want to set Control properties from within this
' method, you must use Control.Invoke method to marshal
' the call to the UI thread; otherwise you might deadlock your
' application; See Control.Invoke documentation for more information
'
Me.Invoke(Me.myUserInterfaceUpdateEvent)
End Sub 'OnSynchronizationCallback
Public Sub OnStartTableDownloadCallback(ByVal ar As IAsyncResult, ByVal tableName As String)
Me.tableName = tableName
Me.eventStatus = SyncStatus.BeginDownload
' NOTE: If you want to set Control properties from within this
' method, you must use Control.Invoke method to marshal
' the call to the UI thread; otherwise you might deadlock your
' application; See Control.Invoke documentation for more information
'
Me.Invoke(Me.myUserInterfaceUpdateEvent)
End Sub 'OnStartTableDownloadCallback
Private Sub ButtonSynchronize_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Try
Me.repl = New SqlCeReplication()
repl.SubscriberConnectionString = "Data Source=Test.sdf"
If False = File.Exists("Test.sdf") Then
repl.AddSubscription(AddOption.CreateDatabase)
repl.PublisherSecurityMode = SecurityType.DBAuthentication
repl.Publisher = "MyPublisher"
repl.PublisherLogin = "PublisherLogin"
repl.PublisherPassword = "<Password>"
repl.PublisherDatabase = "AdventureWorksDW"
repl.Publication = "AdventureWorksDW"
repl.InternetUrl = "https://www.adventure-works.com/sqlmobile/sqlcesa35.dll"
repl.InternetLogin = "InternetLogin"
repl.InternetPassword = "<Password>"
repl.Subscriber = "MySubscriber"
Else
repl.LoadProperties()
End If
Dim ar As IAsyncResult = repl.BeginSynchronize( _
New AsyncCallback(AddressOf Me.SyncCompletedCallback), _
New OnStartTableUpload(AddressOf Me.OnStartTableUploadCallback), _
New OnStartTableDownload(AddressOf Me.OnStartTableDownloadCallback), _
New OnSynchronization(AddressOf Me.OnSynchronizationCallback), repl)
Catch ex As SqlCeException
MessageBox.Show(ex.Message)
End Try
End Sub 'ButtonSynchronize_Click
Public Function GetLastSuccessfulSyncTime() As DateTime
Dim localDateTime As DateTime
Dim conn As SqlCeConnection = Nothing
Dim cmd As SqlCeCommand = Nothing
Try
conn = New SqlCeConnection("Data Source = Test.sdf")
conn.Open()
cmd = conn.CreateCommand()
cmd.CommandText = "SELECT LastSuccessfulSync FROM __sysMergeSubscriptions " & _
"WHERE Publication=@publication"
cmd.Parameters.Add("@publication", SqlDbType.NVarChar, 4000)
cmd.Parameters("@publication").Value = "AdventureWorksDW"
'Note: LastSuccessfulSync is stored in local time, not UTC time
localDateTime = CType(cmd.ExecuteScalar(), DateTime)
Return localDateTime
Finally
conn.Close()
End Try
End Function 'GetLastSuccessfulSyncTime
End Class 'MyForm