Como tratar conflitos de dados e erros
Este tópico mostra como tratar conflitos de dados e erros no Sync Framework. Os exemplos neste tópico se concentram nos seguintes eventos e tipos do Sync Framework:
Os eventos DbServerSyncProvider ApplyChangeFailed e SqlCeClientSyncProvider ApplyChangeFailed e ApplyChangeFailedEventArgs
Para obter informações sobre como executar o código de exemplo, consulte "Exemplo de aplicativos nos tópicos de instruções" em Programando tarefas comuns de sincronização do cliente e do servidor.
Entendendo os conflitos de dados e erros
No Sync Framework, os conflitos e erros são detectados no nível da linha. Uma linha está em conflito se ela foi alterada em mais de um nó entre as sincronizações. Normalmente, os erros que ocorrem durante a sincronização envolvem uma violação de restrição, por exemplo, uma chave primária duplicada. Os aplicativos devem ser projetados para evitar conflitos, se puderem, uma vez que a resolução e detecção de conflitos introduzem complexidade, processamento e tráfego de rede adicionais. As maneiras mais comuns de evitar conflitos são: atualizar uma tabela em apenas um nó (geralmente no servidor) ou filtrar dados para que somente um nó atualize uma determinada linha. Para obter mais informações sobre filtragem, consulte Como filtrar linhas e colunas. Em alguns aplicativos, os conflitos não podem ser evitados. Por exemplo, em um aplicativo de força de vendas, dois vendedores podem dividir um território. Ambos os vendedores podem atualizar os dados para o mesmo cliente e as mesmas ordens. Portanto, o Sync Framework fornece um conjunto de recursos que podem ser usados para detectar e resolver conflitos.
Os conflitos de dados podem ocorrer em qualquer cenário de sincronização no qual as alterações sejam feitas em mais de um nó. Obviamente, os conflitos podem ocorrer na sincronização bidirecional, mas também podem ocorrer nas sincronizações somente para download e somente para upload. Por exemplo, se uma linha for excluída no servidor e a mesma linha for atualizada no cliente, haverá um conflito quando o Sync Framework tentar aplicar a atualização carregada no servidor. Os conflitos são sempre entre o servidor e o cliente que atualmente está sincronizando. Considere o exemplo a seguir:
O cliente A e o cliente B sincronizam com o servidor.
Uma linha é atualizada no cliente A e, em seguida, o cliente A sincroniza. Não há nenhum conflito, e a linha é aplicada no servidor.
A mesma linha é atualizada no cliente B e, em seguida, o cliente B sincroniza. A linha do cliente B agora está em conflito com a linha do servidor por causa da atualização gerada no cliente A.
Se você resolver esse conflito a favor do servidor, o Sync Framework poderá aplicar a linha do servidor no cliente B. Se você resolver a favor do cliente B, o Sync Framework poderá aplicar a linha do cliente B no servidor. Durante uma sincronização posterior entre o cliente A e o servidor, a atualização originada no cliente B é aplicada no cliente A.
Tipos de conflitos e erros
O Sync Framework detecta os seguintes tipos de conflitos. Esses conflitos são definidos na enumeração ConflictType:
Ocorre um conflito de ClientInsertServerInsert quando o cliente e o servidor inserem uma linha com a mesma chave primária. Esse tipo de conflito também é conhecido como uma colisão de chave primária.
Ocorre um conflito de ClientUpdateServerUpdate quando o cliente e o servidor alteram a mesma linha. Este é o tipo mais comum de conflito.
Ocorre um conflito de ClientUpdateServerDelete quando o cliente atualiza uma linha e o servidor exclui a mesma linha.
Ocorre um conflito de ClientDeleteServerUpdate quando o cliente exclui uma linha e o servidor atualiza a mesma linha.
Um conflito ErrorsOccurred ocorre quando um erro impede que uma linha seja aplicada.
Detecção de conflitos e erros
Se uma linha não puder ser aplicada durante a sincronização, normalmente será devido a um erro ou conflito de dados. Em ambos os casos, o evento DbServerSyncProvider ApplyChangeFailed ou SqlCeClientSyncProvider ApplyChangeFailed é gerado, dependendo se o erro ou o conflito ocorreu durante uma fase de upload ou download da sincronização. Se o evento ApplyChangeFailed do cliente for gerado, o Sync Framework selecionará quaisquer linhas conflitantes para você. Em seguida, decida como resolver esses conflitos. Se o evento ApplyChangeFailed do servidor for gerado, as linhas conflitantes serão selecionadas com dois comandos definidos no SyncAdapter para cada tabela:
A consulta ou o procedimento armazenado que você especifica para a propriedade SelectConflictUpdatedRowsCommand seleciona as linhas em conflito na tabela base do banco de dados do servidor. O Sync Framework executará esse comando se uma operação de inserção, atualização ou exclusão retornar um valor @sync_row_count igual a 0. Esse valor indica que houve falha na operação. Esse comando seleciona as linhas de conflitos de ClientInsertServerInsert, ClientUpdateServerUpdate e ClientDeleteServerUpdate.
A consulta ou o procedimento armazenado especificado para o SelectConflictDeletedRowsCommand seleciona as linhas conflitantes a partir da tabela de marcas de exclusão no banco de dados do servidor. O Sync Framework executa esse comando se a linha conflitante não foi encontrada na tabela base. Esse comando seleciona as linhas do conflito ClientUpdateServerDelete.
Os dados de cada linha em conflito são armazenados em uma coleção SyncConflict. Essa coleção pode ficar grande o bastante para causar um erro de memória insuficiente nestas situações:
Há muitas linhas conflitantes. Considere a possibilidade de sincronizar um número menor de linhas em cada sessão ou limite o número de conflitos atualizando uma determinada linha em apenas um nó.
As linhas em conflito contêm colunas que usam tipos de dados grandes. Considere a possibilidade de não incluir as colunas que usam tipos de dados grandes no conjunto de colunas a ser sincronizado. Para obter mais informações, consulte Como filtrar linhas e colunas.
Resolução de conflitos e erros
A resolução de conflitos e erros deve ser tratada em resposta aos eventos DbServerSyncProvider ApplyChangeFailed e SqlCeClientSyncProvider ApplyChangeFailed. O objeto ApplyChangeFailedEventArgs fornece acesso a várias propriedades que podem ser usadas durante a resolução de conflitos:
Especifique como resolver o conflito definindo a propriedade Action para um dos valores da enumeração ApplyAction:
Continue: ignorar o conflito e continuar a sincronização.
RetryApplyingRow: repetir a aplicação da linha. Haverá falha na nova tentativa, e o evento será gerado novamente se você não solucionar a causa do conflito, alterando uma ou ambas as linhas conflitantes.
RetryWithForceWrite: repetir com lógica para forçar a aplicação da alteração. O SqlCeClientSyncProvider possui suporte interno para essa opção. Para usar essa opção no servidor, use o parâmetro @sync_force_write e adicione suporte nos comandos que aplicam alterações ao banco de dados do servidor. Por exemplo, para um conflito ClientUpdateServerDelete, você poderia alterar a atualização em uma inserção se @sync_force_write estivesse definido como 1. Para ver o código de exemplo, consulte a seção "Exemplos" mais adiante neste tópico.
Obtenha o tipo de conflito e visualize as linhas conflitantes a partir do cliente e servidor com a propriedade Conflict.
Obtenha o conjunto de dados das alterações que está sendo sincronizado usando a propriedade Context. As linhas expostas pela propriedade Conflict são cópias; portanto, a substituição delas não altera as linhas aplicadas. Use o conjunto de dados exposto pela propriedade Context para desenvolver os esquemas de resolução personalizados se o aplicativo os exigir. Para ver o código de exemplo, consulte a seção "Exemplos" mais adiante neste tópico.
O SqlCeClientSyncProvider também inclui uma propriedade ConflictResolver que pode ser usada para resolver conflitos no cliente. Para cada tipo de conflito, você pode definir um valor a partir da enumeração ResolveAction:
ClientWins: equivalente a definir ApplyAction de Continue.
ServerWins: equivalente a definir ApplyAction de RetryWithForceWrite.
FireEvent: disparar o evento ApplyChangeFailed (o padrão) e, em seguida, tratar o evento.
Não há nenhum requisito para definir ConflictResolver para cada tipo de conflito. Você pode resolver conflitos da mesma maneira como no servidor, tratando o evento ApplyChangeFailed. No entanto, a propriedade ConflictResolver fornece uma maneira fácil de especificar as opções de resolução de conflitos no cliente.
Exemplo
Os exemplos de código a seguir mostram como configurar a resolução e detecção de conflitos para a tabela Customer no banco de dados de amostra Sync Framework. Nesse exemplo, os comandos sincronização são criados manualmente em vez de usar o SqlSyncAdapterBuilder. Você pode usar a resolução e detecção de conflitos com os comandos gerados pelo SqlSyncAdapterBuilder, mas os comandos manuais fornecem muito mais flexibilidade, especialmente sobre como você pode forçar a aplicação de alterações conflitantes.
Partes principais da API
Esta seção fornece exemplos de código que destacam as partes principais da API usadas na resolução e detecção de conflitos. A consulta a seguir seleciona linhas conflitantes a partir da tabela base no banco de dados do servidor.
SqlCommand customerUpdateConflicts = new SqlCommand();
customerUpdateConflicts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE CustomerId = @CustomerId";
customerUpdateConflicts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerUpdateConflicts.Connection = serverConn;
customerSyncAdapter.SelectConflictUpdatedRowsCommand = customerUpdateConflicts;
Dim customerUpdateConflicts As New SqlCommand()
With customerUpdateConflicts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " + "WHERE CustomerId = @CustomerId"
.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectConflictUpdatedRowsCommand = customerUpdateConflicts
A consulta a seguir seleciona linhas conflitantes a partir da tabela de marcas de exclusão no banco de dados do servidor.
SqlCommand customerDeleteConflicts = new SqlCommand();
customerDeleteConflicts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer_Tombstone " +
"WHERE CustomerId = @CustomerId";
customerDeleteConflicts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerDeleteConflicts.Connection = serverConn;
customerSyncAdapter.SelectConflictDeletedRowsCommand = customerDeleteConflicts;
Dim customerDeleteConflicts As New SqlCommand()
With customerDeleteConflicts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer_Tombstone " + "WHERE CustomerId = @CustomerId"
.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectConflictDeletedRowsCommand = customerDeleteConflicts
O exemplo de código a seguir cria um procedimento armazenado que aplica atualizações no banco de dados do servidor. Esse procedimento é especificado para a propriedade UpdateCommand. Os procedimentos armazenados também podem ser usados para aplicar inserções e exclusões no banco de dados do servidor. Para obter exemplos desses procedimentos, consulte Scripts de instalação para tópicos de instruções do provedor de banco de dados.
O procedimento de atualização usp_CustomerApplyUpdate tenta uma operação de atualização ou inserção, com base no valor do parâmetro @sync_force_write e se a linha para atualização existir no banco de dados do servidor. Se a linha não existir, o procedimento transforma a atualização em uma operação de inserção. Nesse exemplo, a linha ausente é gerada por um conflito de atualização/exclusão.
CREATE PROCEDURE usp_CustomerApplyUpdate (
@sync_last_received_anchor binary(8),
@sync_client_id uniqueidentifier,
@sync_force_write int,
@sync_row_count int out,
@CustomerId uniqueidentifier,
@CustomerName nvarchar(100),
@SalesPerson nvarchar(100),
@CustomerType nvarchar(100))
AS
-- Try to apply an update if the RetryWithForceWrite option
-- was not specified for the sync adapter's update command.
IF @sync_force_write = 0
BEGIN
UPDATE Sales.Customer
SET CustomerName = @CustomerName, SalesPerson = @SalesPerson,
CustomerType = @CustomerType, UpdateId = @sync_client_id
WHERE CustomerId = @CustomerId
AND (UpdateTimestamp <= @sync_last_received_anchor
OR UpdateId = @sync_client_id)
END
ELSE
-- Try to apply an update if the RetryWithForceWrite option
-- was specified for the sync adapter's update command.
BEGIN
--If the row exists, update it.
-- You might want to include code here to handle
-- possible error conditions.
IF EXISTS (SELECT CustomerId FROM Sales.Customer
WHERE CustomerId = @CustomerId)
BEGIN
UPDATE Sales.Customer
SET CustomerName = @CustomerName, SalesPerson = @SalesPerson,
CustomerType = @CustomerType, UpdateId = @sync_client_id
WHERE CustomerId = @CustomerId
END
-- The row does not exist, possibly due to a client-update/
-- server-delete conflict. Change the update into an insert.
ELSE
BEGIN
INSERT INTO Sales.Customer
(CustomerId, CustomerName, SalesPerson,
CustomerType, UpdateId)
VALUES (@CustomerId, @CustomerName, @SalesPerson,
@CustomerType, @sync_client_id)
END
END
SET @sync_row_count = @@rowcount
O exemplo de código a seguir define as opções de resolução de conflito para SqlCeClientSyncProvider. Como pode ter sido observado antes, essas opções não são obrigatórias, mas elas fornecem uma maneira fácil de resolver conflitos. Nesse exemplo, as atualizações sempre devem prevalecer nos conflitos de atualização/exclusão, e todos os outros conflitos devem gerar o evento ApplyChangeFailed do cliente.
this.ConflictResolver.ClientDeleteServerUpdateAction = ResolveAction.ServerWins;
this.ConflictResolver.ClientUpdateServerDeleteAction = ResolveAction.ClientWins;
//If any of the following conflicts or errors occur, the ApplyChangeFailed
//event is raised.
this.ConflictResolver.ClientInsertServerInsertAction = ResolveAction.FireEvent;
this.ConflictResolver.ClientUpdateServerUpdateAction = ResolveAction.FireEvent;
this.ConflictResolver.StoreErrorAction = ResolveAction.FireEvent;
//Log information for the ApplyChangeFailed event and handle any
//ResolveAction.FireEvent cases.
this.ApplyChangeFailed +=new EventHandler<ApplyChangeFailedEventArgs>(SampleClientSyncProvider_ApplyChangeFailed);
Me.ConflictResolver.ClientDeleteServerUpdateAction = ResolveAction.ServerWins
Me.ConflictResolver.ClientUpdateServerDeleteAction = ResolveAction.ClientWins
'If any of the following conflicts or errors occur, the ApplyChangeFailed
'event is raised.
Me.ConflictResolver.ClientInsertServerInsertAction = ResolveAction.FireEvent
Me.ConflictResolver.ClientUpdateServerUpdateAction = ResolveAction.FireEvent
Me.ConflictResolver.StoreErrorAction = ResolveAction.FireEvent
'Log information for the ApplyChangeFailed event and handle any
'ResolveAction.FireEvent cases.
AddHandler Me.ApplyChangeFailed, AddressOf SampleClientSyncProvider_ApplyChangeFailed
Para os conflitos de atualização de cliente/exclusão de servidor, a atualização é gravada forçada no servidor, como pode ser visto no exemplo de código a seguir. O conflito de atualização de cliente/exclusão de servidor é controlado no servidor com a opção RetryWithForceWrite no manipulador de eventos ApplyChangeFailed do servidor. Quando você usa essa opção, isso significa que o parâmetro @sync_force_write está definido como 1 quando o procedimento armazenado de atualização é chamado no servidor.
if (e.Conflict.ConflictType == ConflictType.ClientUpdateServerDelete)
{
//For client-update/server-delete conflicts, we force the client
//change to be applied at the server. The stored procedure specified for
//customerSyncAdapter.UpdateCommand accepts the @sync_force_write parameter
//and includes logic to handle this case.
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client update / server delete conflict was detected.");
e.Action = ApplyAction.RetryWithForceWrite;
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.");
Console.WriteLine("***********************************");
Console.WriteLine(String.Empty);
}
If e.Conflict.ConflictType = ConflictType.ClientUpdateServerDelete Then
'For client-update/server-delete conflicts, we force the client
'change to be applied at the server. The stored procedure specified for
'customerSyncAdapter.UpdateCommand accepts the @sync_force_write parameter
'and includes logic to handle this case.
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client update / server delete conflict was detected.")
e.Action = ApplyAction.RetryWithForceWrite
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.")
Console.WriteLine("***********************************")
Console.WriteLine(String.Empty)
End If
O exemplo de código a seguir registra as informações de conflito e faz gravações forçadas de quaisquer inserções conflitantes no manipulador de eventos ApplyChangeFailed do cliente.
private void SampleClientSyncProvider_ApplyChangeFailed(object sender, ApplyChangeFailedEventArgs e)
{
//Log event data from the client side.
EventLogger.LogEvents(sender, e);
//Force write any inserted server rows that are in conflict
//when they are downloaded.
if (e.Conflict.ConflictType == ConflictType.ClientInsertServerInsert)
{
e.Action = ApplyAction.RetryWithForceWrite;
}
if (e.Conflict.ConflictType == ConflictType.ClientUpdateServerUpdate)
{
//Logic goes here.
}
if (e.Conflict.ConflictType == ConflictType.ErrorsOccurred)
{
//Logic goes here.
}
}
Private Sub SampleClientSyncProvider_ApplyChangeFailed(ByVal sender As Object, ByVal e As ApplyChangeFailedEventArgs)
'Log event data from the client side.
EventLogger.LogEvents(sender, e)
'Force write any inserted server rows that are in conflict
'when they are downloaded.
If e.Conflict.ConflictType = ConflictType.ClientInsertServerInsert Then
e.Action = ApplyAction.RetryWithForceWrite
End If
If e.Conflict.ConflictType = ConflictType.ClientUpdateServerUpdate Then
'Logic goes here.
End If
If e.Conflict.ConflictType = ConflictType.ErrorsOccurred Then
'Logic goes here.
End If
End Sub 'SampleClientSyncProvider_ApplyChangeFailed
Exemplo de código completo
O exemplo de código completo a seguir inclui os exemplos de código descritos anteriormente e o código adicional para executar a sincronização. Além disso, saiba que o exemplo fornece aos usuários do aplicativo uma opção de como resolver os conflitos de atualização/atualização. Uma das opções é um esquema de resolução personalizado que combina valores de coluna das linhas conflitantes. O código para o esquema de resolução personalizado está contido nos manipuladores de eventos SampleServerSyncProvider_ApplyChangeFailed e SampleServerSyncProvider_ChangesApplied. O exemplo requer a classe Utility disponível em Classe de utilitário para tópicos de instruções do provedor de banco de dados.
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlServerCe;
using Microsoft.Synchronization;
using Microsoft.Synchronization.Data;
using Microsoft.Synchronization.Data.Server;
using Microsoft.Synchronization.Data.SqlServerCe;
namespace Microsoft.Samples.Synchronization
{
class Program
{
static void Main(string[] args)
{
//The SampleStats class handles information from the SyncStatistics
//object that the Synchronize method returns.
SampleStats sampleStats = new SampleStats();
//Request a password for the client database, and delete
//and re-create the database. The client synchronization
//provider also enables you to create the client database
//if it does not exist.
Utility.SetPassword_SqlCeClientSync();
Utility.DeleteAndRecreateCompactDatabase(Utility.ConnStr_SqlCeClientSync, true);
//Initial synchronization. Instantiate the SyncAgent
//and call Synchronize.
SampleSyncAgent sampleSyncAgent = new SampleSyncAgent();
SyncStatistics syncStatistics = sampleSyncAgent.Synchronize();
sampleStats.DisplayStats(syncStatistics, "initial");
//Make a change at the client that fails when it is
//applied at the server.
Utility.MakeFailingChangeOnClient();
//Make changes at the client and server that conflict
//when they are synchronized.
Utility.MakeConflictingChangesOnClientAndServer();
//Subsequent synchronization.
syncStatistics = sampleSyncAgent.Synchronize();
sampleStats.DisplayStats(syncStatistics, "subsequent");
//Return server data back to its original state.
//Comment out this line if you want to view the
//state of the data after all conflicts are resolved.
Utility.CleanUpServer();
//Exit.
Console.Write("\nPress Enter to close the window.");
Console.ReadLine();
}
}
//Create a class that is derived from
//Microsoft.Synchronization.SyncAgent.
public class SampleSyncAgent : SyncAgent
{
public SampleSyncAgent()
{
//Instantiate a client synchronization provider and specify it
//as the local provider for this synchronization agent.
this.LocalProvider = new SampleClientSyncProvider();
//Instantiate a server synchronization provider and specify it
//as the remote provider for this synchronization agent.
this.RemoteProvider = new SampleServerSyncProvider();
//Add the Customer table: specify a synchronization direction
//of Bidirectional.
SyncTable customerSyncTable = new SyncTable("Customer");
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerSyncTable.SyncDirection = SyncDirection.Bidirectional;
this.Configuration.SyncTables.Add(customerSyncTable);
}
}
//Create a class that is derived from
//Microsoft.Synchronization.Server.DbServerSyncProvider.
public class SampleServerSyncProvider : DbServerSyncProvider
{
public SampleServerSyncProvider()
{
//Create a connection to the sample server database.
Utility util = new Utility();
SqlConnection serverConn = new SqlConnection(Utility.ConnStr_DbServerSync);
this.Connection = serverConn;
//Create a command to retrieve a new anchor value from
//the server. In this case, we use a timestamp value
//that is retrieved and stored in the client database.
//During each synchronization, the new anchor value and
//the last anchor value from the previous synchronization
//are used: the set of changes between these upper and
//lower bounds is synchronized.
//
//SyncSession.SyncNewReceivedAnchor is a string constant;
//you could also use @sync_new_received_anchor directly in
//your queries.
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, and then define
//the commands to synchronize changes:
//* SelectConflictUpdatedRowsCommand SelectConflictDeletedRowsCommand
// are used to detect if there are conflicts on the server during
// synchronization.
//* SelectIncrementalInsertsCommand, SelectIncrementalUpdatesCommand,
// and SelectIncrementalDeletesCommand are used to select changes
// from the server that the client provider then applies to the client.
//* InsertCommand, UpdateCommand, and DeleteCommand are used to apply
// to the server the changes that the client provider has selected
// from the client.
//Create the SyncAdapter.
SyncAdapter customerSyncAdapter = new SyncAdapter("Customer");
//This command is used if @sync_row_count returns
//0 when changes are applied to the server.
SqlCommand customerUpdateConflicts = new SqlCommand();
customerUpdateConflicts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE CustomerId = @CustomerId";
customerUpdateConflicts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerUpdateConflicts.Connection = serverConn;
customerSyncAdapter.SelectConflictUpdatedRowsCommand = customerUpdateConflicts;
//This command is used if the server provider cannot find
//a row in the base table.
SqlCommand customerDeleteConflicts = new SqlCommand();
customerDeleteConflicts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer_Tombstone " +
"WHERE CustomerId = @CustomerId";
customerDeleteConflicts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerDeleteConflicts.Connection = serverConn;
customerSyncAdapter.SelectConflictDeletedRowsCommand = customerDeleteConflicts;
//Select inserts from the server.
SqlCommand customerIncrInserts = new SqlCommand();
customerIncrInserts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE (InsertTimestamp > @sync_last_received_anchor " +
"AND InsertTimestamp <= @sync_new_received_anchor " +
"AND InsertId <> @sync_client_id)";
customerIncrInserts.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrInserts.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrInserts.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerIncrInserts.Connection = serverConn;
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts;
//Apply inserts to the server.
SqlCommand customerInserts = new SqlCommand();
customerInserts.CommandType = CommandType.StoredProcedure;
customerInserts.CommandText = "usp_CustomerApplyInsert";
customerInserts.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerInserts.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit);
customerInserts.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output;
customerInserts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerInserts.Parameters.Add("@CustomerName", SqlDbType.NVarChar);
customerInserts.Parameters.Add("@SalesPerson", SqlDbType.NVarChar);
customerInserts.Parameters.Add("@CustomerType", SqlDbType.NVarChar);
customerInserts.Connection = serverConn;
customerSyncAdapter.InsertCommand = customerInserts;
//Select updates from the server.
SqlCommand customerIncrUpdates = new SqlCommand();
customerIncrUpdates.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE (UpdateTimestamp > @sync_last_received_anchor " +
"AND UpdateTimestamp <= @sync_new_received_anchor " +
"AND UpdateId <> @sync_client_id " +
"AND NOT (InsertTimestamp > @sync_last_received_anchor " +
"AND InsertId <> @sync_client_id))";
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerIncrUpdates.Connection = serverConn;
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates;
//Apply updates to the server.
SqlCommand customerUpdates = new SqlCommand();
customerUpdates.CommandType = CommandType.StoredProcedure;
customerUpdates.CommandText = "usp_CustomerApplyUpdate";
customerUpdates.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerUpdates.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerUpdates.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit);
customerUpdates.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output;
customerUpdates.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerUpdates.Parameters.Add("@CustomerName", SqlDbType.NVarChar);
customerUpdates.Parameters.Add("@SalesPerson", SqlDbType.NVarChar);
customerUpdates.Parameters.Add("@CustomerType", SqlDbType.NVarChar);
customerUpdates.Connection = serverConn;
customerSyncAdapter.UpdateCommand = customerUpdates;
//Select deletes from the server.
SqlCommand customerIncrDeletes = new SqlCommand();
customerIncrDeletes.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer_Tombstone " +
"WHERE (@sync_initialized = 1 " +
"AND DeleteTimestamp > @sync_last_received_anchor " +
"AND DeleteTimestamp <= @sync_new_received_anchor " +
"AND DeleteId <> @sync_client_id)";
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncInitialized, SqlDbType.Bit);
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerIncrDeletes.Connection = serverConn;
customerSyncAdapter.SelectIncrementalDeletesCommand = customerIncrDeletes;
//Apply deletes to the server.
SqlCommand customerDeletes = new SqlCommand();
customerDeletes.CommandType = CommandType.StoredProcedure;
customerDeletes.CommandText = "usp_CustomerApplyDelete";
customerDeletes.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerDeletes.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier);
customerDeletes.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit);
customerDeletes.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output;
customerDeletes.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier);
customerDeletes.Connection = serverConn;
customerSyncAdapter.DeleteCommand = customerDeletes;
//Add the SyncAdapter to the server synchronization provider.
this.SyncAdapters.Add(customerSyncAdapter);
//Handle the ApplyChangeFailed and ChangesApplied events.
//This allows us to respond to any conflicts that occur, and to
//make changes that are downloaded to the client during the same
//session.
this.ApplyChangeFailed +=new EventHandler<ApplyChangeFailedEventArgs>(SampleServerSyncProvider_ApplyChangeFailed);
this.ChangesApplied +=new EventHandler<ChangesAppliedEventArgs>(SampleServerSyncProvider_ChangesApplied);
}
//Create a list to hold primary keys from the Customer
//table. This list is used when we handle the ApplyChangeFailed
//and ChangesApplied events.
private List<Guid> _updateConflictGuids = new List<Guid>();
private void SampleServerSyncProvider_ApplyChangeFailed(object sender, ApplyChangeFailedEventArgs e)
{
//Log information for the ApplyChangeFailed event.
EventLogger.LogEvents(sender, e);
//Respond to four different types of conflicts:
// * ClientDeleteServerUpdate
// * ClientUpdateServerDelete
// * ClientInsertServerInsert
// * ClientUpdateServerUpdate
//
if (e.Conflict.ConflictType == ConflictType.ClientDeleteServerUpdate)
{
//With the commands we are using, the default is for the server
//change to win and be applied to the client. Here, we accept the
//default on the server side. We also set ConflictResolver.ServerWins
//for this conflict in the client provider. This ensures that the server
//change is applied to the client during the download phase.
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client delete / server update conflict was detected.");
e.Action = ApplyAction.Continue;
Console.WriteLine("The server change will be applied at the client.");
Console.WriteLine("***********************************");
Console.WriteLine(String.Empty);
}
if (e.Conflict.ConflictType == ConflictType.ClientUpdateServerDelete)
{
//For client-update/server-delete conflicts, we force the client
//change to be applied at the server. The stored procedure specified for
//customerSyncAdapter.UpdateCommand accepts the @sync_force_write parameter
//and includes logic to handle this case.
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client update / server delete conflict was detected.");
e.Action = ApplyAction.RetryWithForceWrite;
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.");
Console.WriteLine("***********************************");
Console.WriteLine(String.Empty);
}
if (e.Conflict.ConflictType == ConflictType.ClientInsertServerInsert)
{
//Similar to how we handled the client-delete/server-update conflict.
//In this case, we set ConflictResolver.FireEvent and use RetryWithForceWrite
//for this conflict in the client provider. This is equivalent to
//ConflictResolver.ServerWins, and ensures that the server
//change is applied to the client during the download phase.
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client insert / server insert conflict was detected.");
e.Action = ApplyAction.Continue;
Console.WriteLine("The server change will be applied at the client.");
Console.WriteLine("***********************************");
Console.WriteLine(String.Empty);
}
if (e.Conflict.ConflictType == ConflictType.ClientUpdateServerUpdate)
{
//For client-update/server-update conflicts, we want to
//allow the user to specify the conflict resolution option.
//
//It is possible for the Conflict object from the
//server to have more than one row. Because our custom
//resolution code only works with one row at a time,
//we only allow the user to select a resolution
//option if the object contains a single row.
if (e.Conflict.ServerChange.Rows.Count > 1)
{
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client update / server update conflict was detected.");
e.Action = ApplyAction.Continue;
Console.WriteLine("The server change will be applied at the client.");
Console.WriteLine("***********************************");
Console.WriteLine(String.Empty);
}
else
{
Console.WriteLine(String.Empty);
Console.WriteLine("***********************************");
Console.WriteLine("A client update / server update conflict was detected.");
Console.WriteLine("Conflicting rows are displayed below.");
Console.WriteLine("***********************************");
//Get the conflicting changes from the Conflict object
//and display them. The Conflict object holds a copy
//of the changes; updates to this object will not be
//applied. To make changes, use the Context object,
//which is demonstrated in the next section of code
//under ' case "CU" '.
DataTable conflictingServerChange = e.Conflict.ServerChange;
DataTable conflictingClientChange = e.Conflict.ClientChange;
int serverColumnCount = conflictingServerChange.Columns.Count;
int clientColumnCount = conflictingClientChange.Columns.Count;
Console.WriteLine(String.Empty);
Console.WriteLine("Server row: ");
Console.Write(" | ");
//Display the server row.
for (int i = 0; i < serverColumnCount; i++)
{
Console.Write(conflictingServerChange.Rows[0][i] + " | ");
}
Console.WriteLine(String.Empty);
Console.WriteLine(String.Empty);
Console.WriteLine("Client row: ");
Console.Write(" | ");
//Display the client row.
for (int i = 0; i < clientColumnCount; i++)
{
Console.Write(conflictingClientChange.Rows[0][i] + " | ");
}
Console.WriteLine(String.Empty);
Console.WriteLine(String.Empty);
//Ask for a conflict resolution option.
Console.WriteLine("Enter a resolution option for this conflict:");
Console.WriteLine("SE = server change wins");
Console.WriteLine("CL = client change wins");
Console.WriteLine("CU = custom resolution (combine rows)");
string conflictResolution = Console.ReadLine();
conflictResolution.ToUpper();
switch (conflictResolution)
{
case "SE":
//Again, this this is the default for the commands we are using:
//the server change is persisted and then downloaded to the client.
e.Action = ApplyAction.Continue;
Console.WriteLine(String.Empty);
Console.WriteLine("The server change will be applied at the client.");
break;
case "CL":
//Override the default by specifying that the client row
//should be applied at the server. The stored procedure specified
//for customerSyncAdapter.UpdateCommand accepts the @sync_force_write
//parameter and includes logic to handle this case.
e.Action = ApplyAction.RetryWithForceWrite;
Console.WriteLine(String.Empty);
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.");
break;
case "CU":
//Provide a custom resolution scheme that takes each conflicting
//column and applies the combined contents of the column to the
//client and server. This is not necessarily a resolution scheme
//that you would use in production. Instead, it is used to
//demonstrate the various ways you can interact with conflicting
//data during synchronization.
//
//Get the ID for the conflicting row from the client data table,
//and add it to a list of GUIDs. We update rows at the server
//based on this list.
Guid customerId = (Guid)conflictingClientChange.Rows[0]["CustomerId"];
_updateConflictGuids.Add(customerId);
//Create a dictionary to hold the column ordinal and value for
//any columns that are in confict.
Dictionary<int, string> conflictingColumns = new Dictionary<int, string>();
string combinedColumnValue;
//Determine which columns are different at the client and server.
//We already looped through these columns once, but we wanted to
//keep this code separate from the display code above.
for (int i = 0; i < clientColumnCount; i++)
{
if (conflictingClientChange.Rows[0][i].ToString() != conflictingServerChange.Rows[0][i].ToString())
{
//If we find a column that is different, combine the values from
//the client and server, and write "| conflict |" between them.
combinedColumnValue = conflictingClientChange.Rows[0][i] + " | conflict | " +
conflictingServerChange.Rows[0][i];
conflictingColumns.Add(i, combinedColumnValue);
}
}
//Loop through the rows in the Context object, which exposes
//the set of changes that are uploaded from the client.
//Note: In the ApplyChangeFailed event for the client provider,
//you have access to the set of changes that was downloaded from
//the server.
DataTable allClientChanges = e.Context.DataSet.Tables["Customer"];
int allClientRowCount = allClientChanges.Rows.Count;
int allClientColumnCount = allClientChanges.Columns.Count;
for (int i = 0; i < allClientRowCount; i++)
{
//Find the changed row with the GUID from the Conflict object.
if (allClientChanges.Rows[i].RowState == DataRowState.Modified &&
(Guid)allClientChanges.Rows[i]["CustomerId"] == customerId)
{
//Loop through the columns and check whether the column
//is in the conflictingColumns dictionary. If it is,
//update the value in the allClientChanges Context object.
for (int j = 0; j < allClientColumnCount; j++)
{
if (conflictingColumns.ContainsKey(j))
{
allClientChanges.Rows[i][j] = conflictingColumns[j];
}
}
}
}
//Apply the changed row with its combined values to the server.
//This change will persist at the server, but it will not be
//downloaded with the SelectIncrementalUpdate command that we use.
//It will not download the change because it checks for the UpdateId,
//which is still set to the client that made the upload.
//We use the ChangesApplied event to set the UpdateId for the
//change to a value that represents the server. This ensures
//that the change is applied at the client during the download
//phase of synchronization (see SampleServerSyncProvider_ChangesApplied).
e.Action = ApplyAction.RetryWithForceWrite;
Console.WriteLine(String.Empty);
Console.WriteLine("The custom change was retried at the server with RetryWithForceWrite.");
break;
default:
Console.WriteLine(String.Empty);
Console.WriteLine("Not a valid resolution option.");
break;
}
}
Console.WriteLine(String.Empty);
}
}
private void SampleServerSyncProvider_ChangesApplied(object sender, ChangesAppliedEventArgs e)
{
//If _updateConflictGuids contains at least one GUID, update the UpdateId
//column so that each change is downloaded to the client. For more
//information, see SampleServerSyncProvider_ApplyChangeFailed.
if (_updateConflictGuids.Count > 0)
{
SqlCommand updateTable = new SqlCommand();
updateTable.Connection = (SqlConnection)e.Connection;
updateTable.Transaction = (SqlTransaction)e.Transaction;
updateTable.CommandText = String.Empty;
for (int i = 0; i < _updateConflictGuids.Count; i++)
{
updateTable.CommandText +=
" UPDATE Sales.Customer SET UpdateId = '00000000-0000-0000-0000-000000000000' " +
" WHERE CustomerId='" + _updateConflictGuids[i].ToString() + "'";
}
updateTable.ExecuteNonQuery();
}
}
}
//Create a class that is derived from
//Microsoft.Synchronization.Data.SqlServerCe.SqlCeClientSyncProvider.
//You can just instantiate the provider directly and associate it
//with the SyncAgent, but here we use this class to handle client
//provider events.
public class SampleClientSyncProvider : SqlCeClientSyncProvider
{
public SampleClientSyncProvider()
{
//Specify a connection string for the sample client database.
//By default, the client database is created if it does not
//exist.
Utility util = new Utility();
this.ConnectionString = Utility.ConnStr_SqlCeClientSync;
//Specify conflict resolution options for each type of
//conflict or error that can occur. The client and server are
//independent; therefore, these settings have no effect when changes
//are applied at the server. However, settings should agree with each
//other. For example:
// * We specify a value of ServerWins for client delete /
// server update. On the server side, by default our commands will
// ignore the conflicting delete and download the update to the
// client. ServerWins is equivalent to setting RetryWithForceWrite
// on the client.
// * Conversely, we specify a value of ClientWins for client update /
// server delete. On the server side, we specify that our commands
// should force write the update by turning it into an insert.
this.ConflictResolver.ClientDeleteServerUpdateAction = ResolveAction.ServerWins;
this.ConflictResolver.ClientUpdateServerDeleteAction = ResolveAction.ClientWins;
//If any of the following conflicts or errors occur, the ApplyChangeFailed
//event is raised.
this.ConflictResolver.ClientInsertServerInsertAction = ResolveAction.FireEvent;
this.ConflictResolver.ClientUpdateServerUpdateAction = ResolveAction.FireEvent;
this.ConflictResolver.StoreErrorAction = ResolveAction.FireEvent;
//Log information for the ApplyChangeFailed event and handle any
//ResolveAction.FireEvent cases.
this.ApplyChangeFailed +=new EventHandler<ApplyChangeFailedEventArgs>(SampleClientSyncProvider_ApplyChangeFailed);
//Use the following events to fix up schema on the client.
//We use the CreatingSchema event to change the schema
//by using the API. We use the SchemaCreated event
//to change the schema by using SQL.
this.CreatingSchema += new EventHandler<CreatingSchemaEventArgs>(SampleClientSyncProvider_CreatingSchema);
this.SchemaCreated += new EventHandler<SchemaCreatedEventArgs>(SampleClientSyncProvider_SchemaCreated);
}
private void SampleClientSyncProvider_ApplyChangeFailed(object sender, ApplyChangeFailedEventArgs e)
{
//Log event data from the client side.
EventLogger.LogEvents(sender, e);
//Force write any inserted server rows that are in conflict
//when they are downloaded.
if (e.Conflict.ConflictType == ConflictType.ClientInsertServerInsert)
{
e.Action = ApplyAction.RetryWithForceWrite;
}
if (e.Conflict.ConflictType == ConflictType.ClientUpdateServerUpdate)
{
//Logic goes here.
}
if (e.Conflict.ConflictType == ConflictType.ErrorsOccurred)
{
//Logic goes here.
}
}
private void SampleClientSyncProvider_CreatingSchema(object sender, CreatingSchemaEventArgs e)
{
//Set the RowGuid property because it is not copied
//to the client by default. This is also a good time
//to specify literal defaults with .Columns[ColName].DefaultValue,
//but we will specify defaults like NEWID() by calling
//ALTER TABLE after the table is created.
e.Schema.Tables["Customer"].Columns["CustomerId"].RowGuid = true;
}
private void SampleClientSyncProvider_SchemaCreated(object sender, SchemaCreatedEventArgs e)
{
string tableName = e.Table.TableName;
Utility util = new Utility();
//Call ALTER TABLE on the client. This must be done
//over the same connection and within the same
//transaction that Sync Framework uses
//to create the schema on the client.
Utility.MakeSchemaChangesOnClient(e.Connection, e.Transaction, "Customer");
}
}
//Handle the statistics that are returned by the SyncAgent.
public class SampleStats
{
public void DisplayStats(SyncStatistics syncStatistics, string syncType)
{
Console.WriteLine(String.Empty);
if (syncType == "initial")
{
Console.WriteLine("****** Initial Synchronization ******");
}
else if (syncType == "subsequent")
{
Console.WriteLine("***** Subsequent Synchronization ****");
}
Console.WriteLine("Start Time: " + syncStatistics.SyncStartTime);
Console.WriteLine("Upload Changes Applied: " + syncStatistics.UploadChangesApplied);
Console.WriteLine("Upload Changes Failed: " + syncStatistics.UploadChangesFailed);
Console.WriteLine("Total Changes Uploaded: " + syncStatistics.TotalChangesUploaded);
Console.WriteLine("Download Changes Applied: " + syncStatistics.DownloadChangesApplied);
Console.WriteLine("Download Changes Failed: " + syncStatistics.DownloadChangesFailed);
Console.WriteLine("Total Changes Downloaded: " + syncStatistics.TotalChangesDownloaded);
Console.WriteLine("Complete Time: " + syncStatistics.SyncCompleteTime);
Console.WriteLine(String.Empty);
}
}
public class EventLogger
{
//Create client and server log files, and write to them
//based on data from the ApplyChangeFailedEventArgs.
public static void LogEvents(object sender, ApplyChangeFailedEventArgs e)
{
string logFile = String.Empty;
string site = String.Empty;
if (sender is SampleServerSyncProvider)
{
logFile = "ServerLogFile.txt";
site = "server";
}
else if (sender is SampleClientSyncProvider)
{
logFile = "ClientLogFile.txt";
site = "client";
}
StreamWriter streamWriter = File.AppendText(logFile);
StringBuilder outputText = new StringBuilder();
outputText.AppendLine("** CONFLICTING CHANGE OR ERROR AT " + site.ToUpper() + " **");
outputText.AppendLine("Table for which error or conflict occurred: " + e.TableMetadata.TableName);
outputText.AppendLine("Sync stage: " + e.Conflict.SyncStage);
outputText.AppendLine("Conflict type: " + e.Conflict.ConflictType);
//If it is a data conflict instead of an error, print out
//the values of the rows at the client and server.
if (e.Conflict.ConflictType != ConflictType.ErrorsOccurred &&
e.Conflict.ConflictType != ConflictType.Unknown)
{
DataTable serverChange = e.Conflict.ServerChange;
DataTable clientChange = e.Conflict.ClientChange;
int serverRows = serverChange.Rows.Count;
int clientRows = clientChange.Rows.Count;
int serverColumns = serverChange.Columns.Count;
int clientColumns = clientChange.Columns.Count;
for (int i = 0; i < serverRows; i++)
{
outputText.Append("Server row: ");
for (int j = 0; j < serverColumns; j++)
{
outputText.Append(serverChange.Rows[i][j] + " | ");
}
outputText.AppendLine(String.Empty);
}
for (int i = 0; i < clientRows; i++)
{
outputText.Append("Client row: ");
for (int j = 0; j < clientColumns; j++)
{
outputText.Append(clientChange.Rows[i][j] + " | ");
}
outputText.AppendLine(String.Empty);
}
}
if (e.Conflict.ConflictType == ConflictType.ErrorsOccurred)
{
outputText.AppendLine("Error message: " + e.Error.Message);
}
streamWriter.WriteLine(DateTime.Now.ToShortTimeString() + " | " + outputText.ToString());
streamWriter.Flush();
streamWriter.Dispose();
}
}
}
Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.IO
Imports System.Text
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlServerCe
Imports Microsoft.Synchronization
Imports Microsoft.Synchronization.Data
Imports Microsoft.Synchronization.Data.Server
Imports Microsoft.Synchronization.Data.SqlServerCe
Class Program
Shared Sub Main(ByVal args() As String)
'The SampleStats class handles information from the SyncStatistics
'object that the Synchronize method returns.
Dim sampleStats As New SampleStats()
'Request a password for the client database, and delete
'and re-create the database. The client synchronization
'provider also enables you to create the client database
'if it does not exist.
Utility.SetPassword_SqlCeClientSync()
Utility.DeleteAndRecreateCompactDatabase(Utility.ConnStr_SqlCeClientSync, True)
'Initial synchronization. Instantiate the SyncAgent
'and call Synchronize.
Dim sampleSyncAgent As New SampleSyncAgent()
Dim syncStatistics As SyncStatistics = sampleSyncAgent.Synchronize()
sampleStats.DisplayStats(syncStatistics, "initial")
'Make a change at the client that fails when it is
'applied at the server.
Utility.MakeFailingChangeOnClient()
'Make changes at the client and server that conflict
'when they are synchronized.
Utility.MakeConflictingChangesOnClientAndServer()
'Subsequent synchronization.
syncStatistics = sampleSyncAgent.Synchronize()
sampleStats.DisplayStats(syncStatistics, "subsequent")
'Return server data back to its original state.
'Comment out this line if you want to view the
'state of the data after all conflicts are resolved.
Utility.CleanUpServer()
'Exit.
Console.Write(vbLf + "Press Enter to close the window.")
Console.ReadLine()
End Sub 'Main
End Class 'Program
'Create a class that is derived from
'Microsoft.Synchronization.SyncAgent.
Public Class SampleSyncAgent
Inherits SyncAgent
Public Sub New()
'Instantiate a client synchronization provider and specify it
'as the local provider for this synchronization agent.
Me.LocalProvider = New SampleClientSyncProvider()
'Instantiate a server synchronization provider and specify it
'as the remote provider for this synchronization agent.
Me.RemoteProvider = New SampleServerSyncProvider()
'Add the Customer table: specify a synchronization direction
'of Bidirectional.
Dim customerSyncTable As New SyncTable("Customer")
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerSyncTable.SyncDirection = SyncDirection.Bidirectional
Me.Configuration.SyncTables.Add(customerSyncTable)
End Sub 'New
End Class 'SampleSyncAgent
'Create a class that is derived from
'Microsoft.Synchronization.Server.DbServerSyncProvider.
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(Utility.ConnStr_DbServerSync)
Me.Connection = serverConn
'Create a command to retrieve a new anchor value from
'the server. In this case, we use a timestamp value
'that is retrieved and stored in the client database.
'During each synchronization, the new anchor value and
'the last anchor value from the previous synchronization
'are used: the set of changes between these upper and
'lower bounds is synchronized.
'
'SyncSession.SyncNewReceivedAnchor is a string constant;
'you could also use @sync_new_received_anchor directly in
'your queries.
Dim selectNewAnchorCommand As New SqlCommand()
Dim newAnchorVariable As String = "@" + SyncSession.SyncNewReceivedAnchor
With selectNewAnchorCommand
.CommandText = "SELECT " + newAnchorVariable + " = min_active_rowversion() - 1"
.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp)
.Parameters(newAnchorVariable).Direction = ParameterDirection.Output
.Connection = serverConn
End With
Me.SelectNewAnchorCommand = selectNewAnchorCommand
'Create a SyncAdapter for the Customer table, and then define
'the commands to synchronize changes:
'* SelectConflictUpdatedRowsCommand SelectConflictDeletedRowsCommand
' are used to detect if there are conflicts on the server during
' synchronization.
'* SelectIncrementalInsertsCommand, SelectIncrementalUpdatesCommand,
' and SelectIncrementalDeletesCommand are used to select changes
' from the server that the client provider then applies to the client.
'* InsertCommand, UpdateCommand, and DeleteCommand are used to apply
' to the server the changes that the client provider has selected
' from the client.
'Create the SyncAdapter.
Dim customerSyncAdapter As New SyncAdapter("Customer")
'This command is used if @sync_row_count returns
'0 when changes are applied to the server.
Dim customerUpdateConflicts As New SqlCommand()
With customerUpdateConflicts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " + "WHERE CustomerId = @CustomerId"
.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectConflictUpdatedRowsCommand = customerUpdateConflicts
'This command is used if the server provider cannot find
'a row in the base table.
Dim customerDeleteConflicts As New SqlCommand()
With customerDeleteConflicts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer_Tombstone " + "WHERE CustomerId = @CustomerId"
.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectConflictDeletedRowsCommand = customerDeleteConflicts
'Select inserts from the server.
Dim customerIncrInserts As New SqlCommand()
With customerIncrInserts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " _
& "WHERE (InsertTimestamp > @sync_last_received_anchor " _
& "AND InsertTimestamp <= @sync_new_received_anchor " _
& "AND InsertId <> @sync_client_id)"
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts
'Apply inserts to the server.
Dim customerInserts As New SqlCommand()
customerInserts.CommandType = CommandType.StoredProcedure
customerInserts.CommandText = "usp_CustomerApplyInsert"
customerInserts.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
customerInserts.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit)
customerInserts.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output
customerInserts.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
customerInserts.Parameters.Add("@CustomerName", SqlDbType.NVarChar)
customerInserts.Parameters.Add("@SalesPerson", SqlDbType.NVarChar)
customerInserts.Parameters.Add("@CustomerType", SqlDbType.NVarChar)
customerInserts.Connection = serverConn
customerSyncAdapter.InsertCommand = customerInserts
'Select updates from the server.
Dim customerIncrUpdates As New SqlCommand()
With customerIncrUpdates
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " _
& "WHERE (UpdateTimestamp > @sync_last_received_anchor " _
& "AND UpdateTimestamp <= @sync_new_received_anchor " _
& "AND UpdateId <> @sync_client_id " _
& "AND NOT (InsertTimestamp > @sync_last_received_anchor " _
& "AND InsertId <> @sync_client_id))"
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates
'Apply updates to the server.
Dim customerUpdates As New SqlCommand()
customerUpdates.CommandType = CommandType.StoredProcedure
customerUpdates.CommandText = "usp_CustomerApplyUpdate"
customerUpdates.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
customerUpdates.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
customerUpdates.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit)
customerUpdates.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output
customerUpdates.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
customerUpdates.Parameters.Add("@CustomerName", SqlDbType.NVarChar)
customerUpdates.Parameters.Add("@SalesPerson", SqlDbType.NVarChar)
customerUpdates.Parameters.Add("@CustomerType", SqlDbType.NVarChar)
customerUpdates.Connection = serverConn
customerSyncAdapter.UpdateCommand = customerUpdates
'Select deletes from the server.
Dim customerIncrDeletes As New SqlCommand()
With customerIncrDeletes
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer_Tombstone " _
& "WHERE (@sync_initialized = 1 " _
& "AND DeleteTimestamp > @sync_last_received_anchor " _
& "AND DeleteTimestamp <= @sync_new_received_anchor " _
& "AND DeleteId <> @sync_client_id)"
.Parameters.Add("@" + SyncSession.SyncInitialized, SqlDbType.Bit)
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalDeletesCommand = customerIncrDeletes
'Apply deletes to the server.
Dim customerDeletes As New SqlCommand()
customerDeletes.CommandType = CommandType.StoredProcedure
customerDeletes.CommandText = "usp_CustomerApplyDelete"
customerDeletes.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
customerDeletes.Parameters.Add("@" + SyncSession.SyncClientId, SqlDbType.UniqueIdentifier)
customerDeletes.Parameters.Add("@" + SyncSession.SyncForceWrite, SqlDbType.Bit)
customerDeletes.Parameters.Add("@" + SyncSession.SyncRowCount, SqlDbType.Int).Direction = ParameterDirection.Output
customerDeletes.Parameters.Add("@CustomerId", SqlDbType.UniqueIdentifier)
customerDeletes.Connection = serverConn
customerSyncAdapter.DeleteCommand = customerDeletes
'Add the SyncAdapter to the server synchronization provider.
Me.SyncAdapters.Add(customerSyncAdapter)
'Handle the ApplyChangeFailed and ChangesApplied events.
'This allows us to respond to any conflicts that occur, and to
'make changes that are downloaded to the client during the same
'session.
AddHandler Me.ApplyChangeFailed, AddressOf SampleServerSyncProvider_ApplyChangeFailed
AddHandler Me.ChangesApplied, AddressOf SampleServerSyncProvider_ChangesApplied
End Sub 'New
'Create a list to hold primary keys from the Customer
'table. This list is used when we handle the ApplyChangeFailed
'and ChangesApplied events.
Private _updateConflictGuids As ArrayList = New ArrayList
Private Sub SampleServerSyncProvider_ApplyChangeFailed(ByVal sender As Object, ByVal e As ApplyChangeFailedEventArgs)
'Log information for the ApplyChangeFailed event.
EventLogger.LogEvents(sender, e)
'Respond to four different types of conflicts:
' * ClientDeleteServerUpdate
' * ClientUpdateServerDelete
' * ClientInsertServerInsert
' * ClientUpdateServerUpdate
'
If e.Conflict.ConflictType = ConflictType.ClientDeleteServerUpdate Then
'With the commands we are using, the default is for the server
'change to win and be applied to the client. Here, we accept the
'default on the server side. We also set ConflictResolver.ServerWins
'for this conflict in the client provider. This ensures that the server
'change is applied to the client during the download phase.
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client delete / server update conflict was detected.")
e.Action = ApplyAction.Continue
Console.WriteLine("The server change will be applied at the client.")
Console.WriteLine("***********************************")
Console.WriteLine(String.Empty)
End If
If e.Conflict.ConflictType = ConflictType.ClientUpdateServerDelete Then
'For client-update/server-delete conflicts, we force the client
'change to be applied at the server. The stored procedure specified for
'customerSyncAdapter.UpdateCommand accepts the @sync_force_write parameter
'and includes logic to handle this case.
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client update / server delete conflict was detected.")
e.Action = ApplyAction.RetryWithForceWrite
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.")
Console.WriteLine("***********************************")
Console.WriteLine(String.Empty)
End If
If e.Conflict.ConflictType = ConflictType.ClientInsertServerInsert Then
'Similar to how we handled the client-delete/server-update conflict.
'In this case, we set ConflictResolver.FireEvent and use RetryWithForceWrite
'for this conflict in the client provider. This is equivalent to
'ConflictResolver.ServerWins, and ensures that the server
'change is applied to the client during the download phase.
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client insert / server insert conflict was detected.")
e.Action = ApplyAction.Continue
Console.WriteLine("The server change will be applied at the client.")
Console.WriteLine("***********************************")
Console.WriteLine(String.Empty)
End If
If e.Conflict.ConflictType = ConflictType.ClientUpdateServerUpdate Then
'For client-update/server-update conflicts, we want to
'allow the user to specify the conflict resolution option.
'
'It is possible for the Conflict object from the
'server to have more than one row. Because our custom
'resolution code only works with one row at a time,
'we only allow the user to select a resolution
'option if the object contains a single row.
If e.Conflict.ServerChange.Rows.Count > 1 Then
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client update / server update conflict was detected.")
e.Action = ApplyAction.Continue
Console.WriteLine("The server change will be applied at the client.")
Console.WriteLine("***********************************")
Console.WriteLine(String.Empty)
Else
Console.WriteLine(String.Empty)
Console.WriteLine("***********************************")
Console.WriteLine("A client update / server update conflict was detected.")
Console.WriteLine("Conflicting rows are displayed below.")
Console.WriteLine("***********************************")
'Get the conflicting changes from the Conflict object
'and display them. The Conflict object holds a copy
'of the changes; updates to this object will not be
'applied. To make changes, use the Context object,
'which is demonstrated in the next section of code
'under ' case "CU" '.
Dim conflictingServerChange As DataTable = e.Conflict.ServerChange
Dim conflictingClientChange As DataTable = e.Conflict.ClientChange
Dim serverColumnCount As Integer = conflictingServerChange.Columns.Count
Dim clientColumnCount As Integer = conflictingClientChange.Columns.Count
Console.WriteLine(String.Empty)
Console.WriteLine("Server row: ")
Console.Write(" | ")
'Display the server row.
Dim i As Integer
For i = 0 To serverColumnCount - 1
Console.Write(conflictingServerChange.Rows(0)(i).ToString() & " | ")
Next i
Console.WriteLine(String.Empty)
Console.WriteLine(String.Empty)
Console.WriteLine("Client row: ")
Console.Write(" | ")
'Display the client row.
For i = 0 To clientColumnCount - 1
Console.Write(conflictingClientChange.Rows(0)(i).ToString() & " | ")
Next i
Console.WriteLine(String.Empty)
Console.WriteLine(String.Empty)
'Ask for a conflict resolution option.
Console.WriteLine("Enter a resolution option for this conflict:")
Console.WriteLine("SE = server change wins")
Console.WriteLine("CL = client change wins")
Console.WriteLine("CU = custom resolution (combine rows)")
Dim conflictResolution As String = Console.ReadLine()
conflictResolution.ToUpper()
Select Case conflictResolution
Case "SE"
'Again, this this is the default for the commands we are using:
'the server change is persisted and then downloaded to the client.
e.Action = ApplyAction.Continue
Console.WriteLine(String.Empty)
Console.WriteLine("The server change will be applied at the client.")
Case "CL"
'Override the default by specifying that the client row
'should be applied at the server. The stored procedure specified
'for customerSyncAdapter.UpdateCommand accepts the @sync_force_write
'parameter and includes logic to handle this case.
e.Action = ApplyAction.RetryWithForceWrite
Console.WriteLine(String.Empty)
Console.WriteLine("The client change was retried at the server with RetryWithForceWrite.")
Case "CU"
'Provide a custom resolution scheme that takes each conflicting
'column and applies the combined contents of the column to the
'client and server. This is not necessarily a resolution scheme
'that you would use in production. Instead, it is used to
'demonstrate the various ways you can interact with conflicting
'data during synchronization.
'
'Get the ID for the conflicting row from the client data table,
'and add it to a list of GUIDs. We update rows at the server
'based on this list.
Dim customerId As Guid = CType(conflictingClientChange.Rows(0)("CustomerId"), Guid)
_updateConflictGuids.Add(customerId)
'Create a hashtable to hold the column ordinal and value for
'any columns that are in confict.
Dim conflictingColumns As Hashtable = New Hashtable()
Dim combinedColumnValue As String
'Determine which columns are different at the client and server.
'We already looped through these columns once, but we wanted to
'keep this code separate from the display code above.
For i = 0 To clientColumnCount - 1
If conflictingClientChange.Rows(0)(i).ToString() <> conflictingServerChange.Rows(0)(i).ToString() Then
'If we find a column that is different, combine the values from
'the client and server, and write "| conflict |" between them.
combinedColumnValue = conflictingClientChange.Rows(0)(i).ToString() _
& " | conflict | " & conflictingServerChange.Rows(0)(i).ToString()
conflictingColumns.Add(i, combinedColumnValue)
End If
Next i
'Loop through the rows in the Context object, which exposes
'the set of changes that are uploaded from the client.
'Note: In the ApplyChangeFailed event for the client provider,
'you have access to the set of changes that was downloaded from
'the server.
Dim allClientChanges As DataTable = e.Context.DataSet.Tables("Customer")
Dim allClientRowCount As Integer = allClientChanges.Rows.Count
Dim allClientColumnCount As Integer = allClientChanges.Columns.Count
For i = 0 To allClientRowCount - 1
'Find the changed row with the GUID from the Conflict object.
If allClientChanges.Rows(i).RowState = DataRowState.Modified AndAlso CType(allClientChanges.Rows(i)("CustomerId"), Guid) = customerId Then
'Loop through the columns and check whether the column
'is in the conflictingColumns hashtable. If it is,
'update the value in the allClientChanges Context object.
Dim j As Integer
For j = 0 To allClientColumnCount - 1
If conflictingColumns.ContainsKey(j) Then
allClientChanges.Rows(i)(j) = conflictingColumns(j)
End If
Next j
End If
Next i
'Apply the changed row with its combined values to the server.
'This change will persist at the server, but it will not be
'downloaded with the SelectIncrementalUpdate command that we use.
'It will not download the change because it checks for the UpdateId,
'which is still set to the client that made the upload.
'We use the ChangesApplied event to set the UpdateId for the
'change to a value that represents the server. This ensures
'that the change is applied at the client during the download
'phase of synchronization (see SampleServerSyncProvider_ChangesApplied).
e.Action = ApplyAction.RetryWithForceWrite
Console.WriteLine(String.Empty)
Console.WriteLine("The custom change was retried at the server with RetryWithForceWrite.")
Case Else
Console.WriteLine(String.Empty)
Console.WriteLine("Not a valid resolution option.")
End Select
End If
Console.WriteLine(String.Empty)
End If
End Sub 'SampleServerSyncProvider_ApplyChangeFailed
Private Sub SampleServerSyncProvider_ChangesApplied(ByVal sender As Object, ByVal e As ChangesAppliedEventArgs)
'If _updateConflictGuids contains at least one GUID, update the UpdateId
'column so that each change is downloaded to the client. For more
'information, see SampleServerSyncProvider_ApplyChangeFailed.
If _updateConflictGuids.Count > 0 Then
Dim updateTable As New SqlCommand()
updateTable.Connection = CType(e.Connection, SqlConnection)
updateTable.Transaction = CType(e.Transaction, SqlTransaction)
updateTable.CommandText = String.Empty
Dim i As Integer
For i = 0 To _updateConflictGuids.Count - 1
updateTable.CommandText += _
" UPDATE Sales.Customer SET UpdateId = '00000000-0000-0000-0000-000000000000' " _
+ " WHERE CustomerId='" + _updateConflictGuids(i).ToString() + "'"
Next i
updateTable.ExecuteNonQuery()
End If
End Sub 'SampleServerSyncProvider_ChangesApplied
End Class 'SampleServerSyncProvider
'Create a class that is derived from
'Microsoft.Synchronization.Data.SqlServerCe.SqlCeClientSyncProvider.
'You can just instantiate the provider directly and associate it
'with the SyncAgent, but here we use this class to handle client
'provider events.
Public Class SampleClientSyncProvider
Inherits SqlCeClientSyncProvider
Public Sub New()
'Specify a connection string for the sample client database.
'By default, the client database is created if it does not
'exist.
Dim util As New Utility()
Me.ConnectionString = Utility.ConnStr_SqlCeClientSync
'Specify conflict resolution options for each type of
'conflict or error that can occur. The client and server are
'independent; therefore, these settings have no effect when changes
'are applied at the server. However, settings should agree with each
'other. For example:
' * We specify a value of ServerWins for client delete /
' server update. On the server side, by default our commands will
' ignore the conflicting delete and download the update to the
' client. ServerWins is equivalent to setting RetryWithForceWrite
' on the client.
' * Conversely, we specify a value of ClientWins for client update /
' server delete. On the server side, we specify that our commands
' should force write the update by turning it into an insert.
Me.ConflictResolver.ClientDeleteServerUpdateAction = ResolveAction.ServerWins
Me.ConflictResolver.ClientUpdateServerDeleteAction = ResolveAction.ClientWins
'If any of the following conflicts or errors occur, the ApplyChangeFailed
'event is raised.
Me.ConflictResolver.ClientInsertServerInsertAction = ResolveAction.FireEvent
Me.ConflictResolver.ClientUpdateServerUpdateAction = ResolveAction.FireEvent
Me.ConflictResolver.StoreErrorAction = ResolveAction.FireEvent
'Log information for the ApplyChangeFailed event and handle any
'ResolveAction.FireEvent cases.
AddHandler Me.ApplyChangeFailed, AddressOf SampleClientSyncProvider_ApplyChangeFailed
'Use the following events to fix up schema on the client.
'We use the CreatingSchema event to change the schema
'by using the API. We use the SchemaCreated event
'to change the schema by using SQL.
AddHandler Me.CreatingSchema, AddressOf SampleClientSyncProvider_CreatingSchema
AddHandler Me.SchemaCreated, AddressOf SampleClientSyncProvider_SchemaCreated
End Sub 'New
Private Sub SampleClientSyncProvider_ApplyChangeFailed(ByVal sender As Object, ByVal e As ApplyChangeFailedEventArgs)
'Log event data from the client side.
EventLogger.LogEvents(sender, e)
'Force write any inserted server rows that are in conflict
'when they are downloaded.
If e.Conflict.ConflictType = ConflictType.ClientInsertServerInsert Then
e.Action = ApplyAction.RetryWithForceWrite
End If
If e.Conflict.ConflictType = ConflictType.ClientUpdateServerUpdate Then
'Logic goes here.
End If
If e.Conflict.ConflictType = ConflictType.ErrorsOccurred Then
'Logic goes here.
End If
End Sub 'SampleClientSyncProvider_ApplyChangeFailed
Private Sub SampleClientSyncProvider_CreatingSchema(ByVal sender As Object, ByVal e As CreatingSchemaEventArgs)
'Set the RowGuid property because it is not copied
'to the client by default. This is also a good time
'to specify literal defaults with .Columns[ColName].DefaultValue,
'but we will specify defaults like NEWID() by calling
'ALTER TABLE after the table is created.
e.Schema.Tables("Customer").Columns("CustomerId").RowGuid = True
End Sub 'SampleClientSyncProvider_CreatingSchema
Private Sub SampleClientSyncProvider_SchemaCreated(ByVal sender As Object, ByVal e As SchemaCreatedEventArgs)
Dim tableName As String = e.Table.TableName
Dim util As New Utility()
'Call ALTER TABLE on the client. This must be done
'over the same connection and within the same
'transaction that Sync Framework uses
'to create the schema on the client.
Utility.MakeSchemaChangesOnClient(e.Connection, e.Transaction, "Customer")
End Sub 'SampleClientSyncProvider_SchemaCreated
End Class 'SampleClientSyncProvider
'Handle the statistics that are returned by the SyncAgent.
Public Class SampleStats
Public Sub DisplayStats(ByVal syncStatistics As SyncStatistics, ByVal syncType As String)
Console.WriteLine(String.Empty)
If syncType = "initial" Then
Console.WriteLine("****** Initial Synchronization ******")
ElseIf syncType = "subsequent" Then
Console.WriteLine("***** Subsequent Synchronization ****")
End If
Console.WriteLine("Start Time: " & syncStatistics.SyncStartTime)
Console.WriteLine("Upload Changes Applied: " & syncStatistics.UploadChangesApplied)
Console.WriteLine("Upload Changes Failed: " & syncStatistics.UploadChangesFailed)
Console.WriteLine("Total Changes Uploaded: " & syncStatistics.TotalChangesUploaded)
Console.WriteLine("Download Changes Applied: " & syncStatistics.DownloadChangesApplied)
Console.WriteLine("Download Changes Failed: " & syncStatistics.DownloadChangesFailed)
Console.WriteLine("Total Changes Downloaded: " & syncStatistics.TotalChangesDownloaded)
Console.WriteLine("Complete Time: " & syncStatistics.SyncCompleteTime)
Console.WriteLine(String.Empty)
End Sub 'DisplayStats
End Class 'SampleStats
Public Class EventLogger
'Create client and server log files, and write to them
'based on data from the ApplyChangeFailedEventArgs.
Public Shared Sub LogEvents(ByVal sender As Object, ByVal e As ApplyChangeFailedEventArgs)
Dim logFile As String = String.Empty
Dim site As String = String.Empty
If TypeOf sender Is SampleServerSyncProvider Then
logFile = "ServerLogFile.txt"
site = "server"
ElseIf TypeOf sender Is SampleClientSyncProvider Then
logFile = "ClientLogFile.txt"
site = "client"
End If
Dim streamWriter As StreamWriter = File.AppendText(logFile)
Dim outputText As New StringBuilder()
outputText.AppendLine("** CONFLICTING CHANGE OR ERROR AT " & site.ToUpper() & " **")
outputText.AppendLine("Table for which error or conflict occurred: " & e.TableMetadata.TableName)
outputText.AppendLine("Sync stage: " & e.Conflict.SyncStage.ToString())
outputText.AppendLine("Conflict type: " & e.Conflict.ConflictType.ToString())
'If it is a data conflict instead of an error, print out
'the values of the rows at the client and server.
If e.Conflict.ConflictType <> ConflictType.ErrorsOccurred AndAlso e.Conflict.ConflictType <> ConflictType.Unknown Then
Dim serverChange As DataTable = e.Conflict.ServerChange
Dim clientChange As DataTable = e.Conflict.ClientChange
Dim serverRows As Integer = serverChange.Rows.Count
Dim clientRows As Integer = clientChange.Rows.Count
Dim serverColumns As Integer = serverChange.Columns.Count
Dim clientColumns As Integer = clientChange.Columns.Count
Dim i As Integer
For i = 0 To serverRows - 1
outputText.Append("Server row: ")
Dim j As Integer
For j = 0 To serverColumns - 1
outputText.Append(serverChange.Rows(i)(j).ToString() & " | ")
Next j
outputText.AppendLine(String.Empty)
Next i
For i = 0 To clientRows - 1
outputText.Append("Client row: ")
Dim j As Integer
For j = 0 To clientColumns - 1
outputText.Append(clientChange.Rows(i)(j).ToString() & " | ")
Next j
outputText.AppendLine(String.Empty)
Next i
End If
If e.Conflict.ConflictType = ConflictType.ErrorsOccurred Then
outputText.AppendLine("Error message: " + e.Error.Message)
End If
streamWriter.WriteLine(DateTime.Now.ToShortTimeString() & " | " + outputText.ToString())
streamWriter.Flush()
streamWriter.Dispose()
End Sub 'LogEvents
End Class 'EventLogger
Consulte também
Conceitos
Programando tarefas comuns de sincronização do cliente e do servidor