Sincronizando o provedor de sincronização de arquivos com outros provedores

Artigo
10/17/2009

Este tópico descreve como criar um aplicativo gerenciado que permite que um provedor de sincronização de arquivos seja sincronizado com outro provedor do Sync Framework. Nesse caso, o outro provedor é um provedor simples, mas você também poderia usar um provedor personalizado padrão. Para obter mais informações sobre provedores simples, consulte Implementando um provedor personalizado simples.

Há dois requisitos principais para o aplicativo:

O aplicativo deve implementar IFileDataRetriever como a interface de transferência de dados entre os dois provedores.
O provedor simples deve usar o mesmo formato para IDs que o provedor de sincronização de arquivos: um GUID de 16 bytes para IDs de réplica; um GUID de 16 bytes precedido por um prefixo de 8 bytes para IDs de item; e um inteiro de 4 bytes para IDs de unidade de alteração.

Exemplos de código gerenciado

Os exemplos desta seção mostram parte do código relevante para sincronizar um provedor de sincronização de arquivos e um provedor simples, concentrando-se nos requisitos de ID e de interface de transferência. Para exibir esse código no contexto de um aplicativo completo, consulte o aplicativo "Sync 101 - Synchronizing a File Synchronization Provider with a Simple Provider" disponível na Code Gallery.

O exemplo de código a seguir mostra como a definição da propriedade IdFormats para o provedor simples corresponde aos requisitos mencionados anteriormente.

public override SyncIdFormatGroup IdFormats
{
    get
    {
        SyncIdFormatGroup idFormats = new SyncIdFormatGroup();
        idFormats.ItemIdFormat.Length = 24;
        idFormats.ItemIdFormat.IsVariableLength = false;
        idFormats.ReplicaIdFormat.Length = 16;
        idFormats.ReplicaIdFormat.IsVariableLength = false;
        idFormats.ChangeUnitIdFormat.Length = 4;
        idFormats.ChangeUnitIdFormat.IsVariableLength = false;

        return idFormats;
    }
}

Public Overrides ReadOnly Property IdFormats() As SyncIdFormatGroup
    Get
        Dim FormatGroup As New SyncIdFormatGroup()

        FormatGroup.ItemIdFormat.Length = 24
        FormatGroup.ItemIdFormat.IsVariableLength = False
        FormatGroup.ReplicaIdFormat.Length = 16
        FormatGroup.ReplicaIdFormat.IsVariableLength = False
        FormatGroup.ChangeUnitIdFormat.Length = 4
        FormatGroup.ChangeUnitIdFormat.IsVariableLength = False

        Return FormatGroup
    End Get
End Property

Os exemplos de código a seguir mostram dois dos métodos necessários para provedores simples: LoadChangeData e InsertItem. Grande parte do código nesses métodos é específica para a implementação de um provedor simples, mas existem duas áreas a serem consideradas.

LoadChangeData é usado para carregar dados enumerados no repositório local (o repositório servido pelo provedor simples). Esse método retorna dados como um objeto SimpleFileDataRetriever, que é a implementação do exemplo de IFileDataRetriever.

public override object LoadChangeData(ItemFieldDictionary keyAndExpectedVersion,
    IEnumerable<SyncId> changeUnitsToLoad,
    RecoverableErrorReportingContext recoverableErrorReportingContext)
{
    // Figure out which item is being asked for

    string localRelativePath;
    long expectedLMT;
    ParseDictionary(keyAndExpectedVersion, out localRelativePath, out expectedLMT);

    string localPath = Path.Combine(this.rootFolder, localRelativePath);
    string currentVersion = File.GetLastWriteTimeUtc(localPath).Ticks.ToString();

    // Check if it changed --- race condition!

    if (File.GetLastWriteTimeUtc(localPath).Ticks != expectedLMT)
    {
        recoverableErrorReportingContext.RecordRecoverableErrorForChange(
            new RecoverableErrorData(null));
        return null;
    }

    // Return
    return new SimpleFileDataRetriever(localRelativePath, null, localPath, File.GetAttributes(localPath));
}

Public Overrides Function LoadChangeData(ByVal keyAndExpectedVersion As ItemFieldDictionary, ByVal changeUnitsToLoad As IEnumerable(Of SyncId), ByVal recoverableErrorReportingContext As RecoverableErrorReportingContext) As Object
    ' Figure out which item is being asked for 

    Dim localRelativePath As String = ""
    Dim expectedLMT As Long
    ParseDictionary(keyAndExpectedVersion, localRelativePath, expectedLMT)

    Dim localPath As String = Path.Combine(Me.rootFolder, localRelativePath)
    Dim currentVersion As String = File.GetLastWriteTimeUtc(localPath).Ticks.ToString()

    ' Check if it changed --- race condition! 

    If File.GetLastWriteTimeUtc(localPath).Ticks <> expectedLMT Then
        recoverableErrorReportingContext.RecordRecoverableErrorForChange(Nothing)
        Return Nothing
    End If

    ' Return 
    Return New SimpleFileDataRetriever(localRelativePath, Nothing, localPath, File.GetAttributes(localPath))
End Function

InsertItem é usado para inserir dados no repositório local oriundos do repositório remoto (o repositório servido pelo provedor de sincronização de arquivos). Esse método converte os dados de item recebidos em um objeto IFileDataRetriever. O método InsertItem também converte os dados.

public override void InsertItem(object itemData,
    IEnumerable<SyncId> changeUnitsToCreate,
    RecoverableErrorReportingContext recoverableErrorReportingContext,
    out ItemFieldDictionary keyAndUpdatedVersion,
    out bool commitKnowledgeAfterThisItem)
{
    // Figure out where to create it

    IFileDataRetriever fileData = (IFileDataRetriever)itemData;

    string localPath = Path.Combine(this.rootFolder, Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name));

    // Check if it is already there --- name collision

    if (File.Exists(localPath))
    {
        recoverableErrorReportingContext.RecordConstraintError(
            ConstructDictionary(Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name)));

        keyAndUpdatedVersion = null;
        commitKnowledgeAfterThisItem = false;

        return;
    }

    // Create it

    File.Copy(fileData.AbsoluteSourceFilePath, localPath);

    // Return particulars to Simple Provider framework

    keyAndUpdatedVersion = ConstructDictionary(
        Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name),
        File.GetLastWriteTimeUtc(localPath).Ticks);

    commitKnowledgeAfterThisItem = false;
}

Public Overrides Sub InsertItem(ByVal itemData As Object, ByVal changeUnitsToCreate As IEnumerable(Of SyncId), ByVal recoverableErrorReportingContext As RecoverableErrorReportingContext, ByRef keyAndUpdatedVersion As ItemFieldDictionary, ByRef commitKnowledgeAfterThisItem As Boolean)
    ' Figure out where to create it 

    Dim fileData As IFileDataRetriever = DirectCast(itemData, IFileDataRetriever)

    Dim localPath As String = Path.Combine(Me.rootFolder, Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name))

    ' Check if it is already there --- name collision 

    If File.Exists(localPath) Then
        recoverableErrorReportingContext.RecordConstraintError(ConstructDictionary(Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name)))

        keyAndUpdatedVersion = Nothing
        commitKnowledgeAfterThisItem = False

        Exit Sub
    End If

    ' Create it 

    File.Copy(fileData.AbsoluteSourceFilePath, localPath)

    ' Return particulars to Simple Provider framework 

    keyAndUpdatedVersion = ConstructDictionary(Path.Combine(fileData.RelativeDirectoryPath, fileData.FileData.Name), File.GetLastWriteTimeUtc(localPath).Ticks)

    commitKnowledgeAfterThisItem = False
End Sub

O exemplo de código a seguir cria a classe SimpleFileDataRetriever, que usa AbsoluteSourceFilePath e RelativeDirectoryPath para identificar os locais de arquivos e usa FileData e FileStream para transferir os dados reais.

class SimpleFileDataRetriever : IFileDataRetriever, IDisposable
{
    private string _relativeLocalFilePath;
    private Stream _sourceStream;
    private string _absoluteSourceFilePath;
    private FileAttributes _attributes;

    public SimpleFileDataRetriever(string relativeLocalFilePath, Stream sourceStream, string absoluteSourceFilePath, FileAttributes attributes)
    { 
        this._relativeLocalFilePath = relativeLocalFilePath;
        this._sourceStream = sourceStream;
        this._attributes = attributes;
        this._absoluteSourceFilePath = absoluteSourceFilePath;
    }

    #region IFileDataRetriever Members

    // If the local store has no concept of absolute file path then return a NotImplementedException here.  
    // The FSP will instead use the stream for file copying.
    // If implemented, return absolute local path including file name.
    public string AbsoluteSourceFilePath
    {
        get 
        { 
            return this._absoluteSourceFilePath; 
        }
    }

    public FileData FileData
    {
        get
        {
            FileInfo fi = new FileInfo(_absoluteSourceFilePath);

            //For the relative path on FileData, provide relative path including file name
            return new FileData(
                _relativeLocalFilePath,
                _attributes,
                fi.CreationTimeUtc,
                fi.LastAccessTimeUtc,
                fi.LastWriteTimeUtc,
                fi.Length);
        }
    }

    public System.IO.Stream FileStream
    {
        get 
        {
            if (this._sourceStream == null)
            {
                this._sourceStream = new FileStream(this._absoluteSourceFilePath, FileMode.Open);
            }

            return _sourceStream; 
        }
    }

    // Must return the relative path without the filename
    public string RelativeDirectoryPath
    {
        get
        {
            return Path.GetDirectoryName(_relativeLocalFilePath);
        }
    }

    #endregion

    #region IDisposable Members

    public void Dispose()
    {
        if (this._sourceStream != null)
        {
            this._sourceStream.Close();
        }
    }

    #endregion
}

    Class SimpleFileDataRetriever
        Implements IFileDataRetriever
        '        Implements IDisposable
        Private _relativeLocalFilePath As String
        Private _sourceStream As Stream
        Private _absoluteSourceFilePath As String
        Private _attributes As FileAttributes

        Public Sub New(ByVal relativeLocalFilePath As String, ByVal sourceStream As Stream, ByVal absoluteSourceFilePath As String, ByVal attributes As FileAttributes)
            Me._relativeLocalFilePath = relativeLocalFilePath
            Me._sourceStream = sourceStream
            Me._attributes = attributes
            Me._absoluteSourceFilePath = absoluteSourceFilePath
        End Sub

#Region "IFileDataRetriever Members"

        ' If the local store has no concept of absolute file path then return a NotImplementedException here. 
        ' The FSP will instead use the stream for file copying. 
        ' If implemented, return absolute local path including file name. 
        Public ReadOnly Property AbsoluteSourceFilePath() As String Implements IFileDataRetriever.AbsoluteSourceFilePath
            Get
                Return Me._absoluteSourceFilePath
            End Get
        End Property

        Public ReadOnly Property FileData() As FileData Implements IFileDataRetriever.FileData
            Get
                Dim fi As New FileInfo(_absoluteSourceFilePath)

                'For the relative path on FileData, provide relative path including file name 
                Return New FileData(_relativeLocalFilePath, _attributes, fi.CreationTimeUtc, fi.LastAccessTimeUtc, fi.LastWriteTimeUtc, fi.Length)
            End Get
        End Property

        Public ReadOnly Property FileStream() As System.IO.Stream Implements IFileDataRetriever.FileStream
            Get
                If Me._sourceStream Is Nothing Then
                    Me._sourceStream = New FileStream(Me._absoluteSourceFilePath, FileMode.Open)
                End If

                Return _sourceStream
            End Get
        End Property

        ' Must return the relative path without the filename 
        Public ReadOnly Property RelativeDirectoryPath() As String Implements IFileDataRetriever.RelativeDirectoryPath
            Get
                Return Path.GetDirectoryName(_relativeLocalFilePath)
            End Get
        End Property

#End Region

#Region "IDisposable Members"

        Public Sub Dispose()
            If Me._sourceStream IsNot Nothing Then
                Me._sourceStream.Close()
            End If
        End Sub

#End Region
    End Class

O exemplo de código a seguir sincroniza os dois provedores. O processo de sincronização é o mesmo se você sincroniza dois provedores de sincronização de arquivos ou dois provedores simples: implemente a interface IFileDataRetriever e use os formatos de ID apropriados para garantir que os dados sejam transferidos da forma correta.

static void DoBidirectionalSync(string pathA, Guid replicaA, string pathB, Guid replicaB)
{
    SyncOperationStatistics stats;
    MySimpleFileProvider providerA = new MySimpleFileProvider(replicaA, pathA);
    FileSyncProvider providerB = new FileSyncProvider(replicaB, pathB);

    //Set the custom provider's conflict resolution policy to custom in order to show 
    //how to perform complex resolution actions.
    providerA.Configuration.ConflictResolutionPolicy = ConflictResolutionPolicy.ApplicationDefined;

    //Register callbacks so that we can handle conflicts if they are detected, and other events.
    RegisterCallbacks(providerA);
    RegisterCallbacks(providerB);

    //Synchronize the two providers that are specified.           
    Console.WriteLine("Sync {0} and {1}...", pathA, pathB);
    SyncOrchestrator agent = new SyncOrchestrator();

    //To avoid writing conflict resolution logic in your matching provider it is good practice to always sync from custom provider
    //to FSP provider first.  That way the FSP will handle all the conflicts itself.  Here we do the opposite to show our custom
    //constraint conflict resolution.
    agent.Direction = SyncDirectionOrder.UploadAndDownload;

    agent.LocalProvider = providerB;
    agent.RemoteProvider = providerA;
    stats = agent.Synchronize();

    //Display the statistics from the SyncOperationStatistics object that is returned 
    //by Synchronize().
    Console.WriteLine("Download Applied:\t {0}", stats.DownloadChangesApplied);
    Console.WriteLine("Download Failed:\t {0}", stats.DownloadChangesFailed);
    Console.WriteLine("Download Total:\t\t {0}", stats.DownloadChangesTotal);
    Console.WriteLine("Upload Total:\t\t {0}", stats.UploadChangesApplied);
    Console.WriteLine("Upload Total:\t\t {0}", stats.UploadChangesFailed);
    Console.WriteLine("Upload Total:\t\t {0}", stats.UploadChangesTotal);
}

Private Shared Sub DoBidirectionalSync(ByVal pathA As String, ByVal replicaA As Guid, ByVal pathB As String, ByVal replicaB As Guid)
    Dim stats As SyncOperationStatistics
    Dim providerA As New MySimpleFileProvider(replicaA, pathA)
    Dim providerB As New FileSyncProvider(replicaB, pathB)

    'Set the custom provider's conflict resolution policy to custom in order to show 
    'how to perform complex resolution actions. 
    providerA.Configuration.ConflictResolutionPolicy = ConflictResolutionPolicy.ApplicationDefined

    'Register callbacks so that we can handle conflicts if they are detected, and other events. 
    RegisterCallbacks(providerA)
    RegisterCallbacks(providerB)

    'Synchronize the two providers that are specified. 
    Console.WriteLine("Sync {0} and {1}...", pathA, pathB)
    Dim agent As New SyncOrchestrator()

    'To avoid writing conflict resolution logic in your matching provider it is good practice to always sync from custom provider 
    'to FSP provider first. That way the FSP will handle all the conflicts itself. Here we do the opposite to show our custom 
    'constraint conflict resolution. 
    agent.Direction = SyncDirectionOrder.UploadAndDownload

    agent.LocalProvider = providerB
    agent.RemoteProvider = providerA
    stats = agent.Synchronize()

    'Display the statistics from the SyncOperationStatistics object that is returned 
    'by Synchronize(). 
    Console.WriteLine("Download Applied:" & vbTab & " {0}", stats.DownloadChangesApplied)
    Console.WriteLine("Download Failed:" & vbTab & " {0}", stats.DownloadChangesFailed)
    Console.WriteLine("Download Total:" & vbTab & vbTab & " {0}", stats.DownloadChangesTotal)
    Console.WriteLine("Upload Total:" & vbTab & vbTab & " {0}", stats.UploadChangesApplied)
    Console.WriteLine("Upload Total:" & vbTab & vbTab & " {0}", stats.UploadChangesFailed)
    Console.WriteLine("Upload Total:" & vbTab & vbTab & " {0}", stats.UploadChangesTotal)
End Sub

Consulte também

Conceitos

Implementando um provedor personalizado simples
Integrando dados de provedores diferentes
Sincronizando arquivos

Sincronizando o provedor de sincronização de arquivos com outros provedores

Exemplos de código gerenciado

Consulte também

Conceitos

Recursos adicionais