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Welcome to Xceed Data Manipulation Compoents for .NET and .NET Standard / Task-Based Help / FTP capabilities / Working with the FtpClient interface / How to send custom commands

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    How to send custom commands
    In This Topic

    The SendCustomCommand method of the FtpClient class and the BeginSendCustomCommand/ EndSendCustomCommand methods of the AsyncFtpClient class are used to send custom FTP commands to an FTP server. This means that commands that can be used from the command prompt FTP, although they might be recognized by some FTP servers, are not guaranteed to work. 

    Not all commands are supported by all FTP servers. In order to determine which commands are supported, you can use the SendCustomCommand or BeginSendCustomCommand/EndSendCustomCommand methods to send the "HELP" command. 

    The SendCustomCommand and BeginSendCustomCommand/EndSendCustomCommand methods do not support custom commands that require a data connection such as STOR (SendFile, BeginSendFile/ EndSendFile), RETR (ReceiveFile, BeginReceiveFile/ EndReceiveFile), NLST and LIST ( GetFolderContents, BeginGetFolderContents/ EndGetFolderContents), etc. For a complete list of the FTP commands that can be sent to an FTP server using either the SendCustomCommand and BeginSendCustomCommand/EndSendCustomCommand methods or another of the FtpClient's methods/properties, refer to the FTP commands glossary topic. 

    AsyncFtpClient's methods now call the corresponding synchronous methods on a background thread. For this reason, the AsyncFtpClient class is now considered obsolete. It is therefore recommended to use FtpClient instead to improve code readability.
    When using Xceed FTP for .NET in a WinForms application, it is recommended that a SynchronizingObject be assigned to the SynchronizingObject property of the FtpClient class. For more information, jump to the WinForms applications and threading topic.

    Synchronous (blocking) and asynchronous (non-blocking) demonstration using FtpClient

    The following example demonstrates how to send the "HELP" command to an FTP server using the SendCustomCommand method. An asynchronous (non-blocking) demonstration is also available further below.

    VB.NET Copy Code

    Imports Xceed.Ftp

    ' When using FtpClient, you can instruct
    ' the library to automatically redirect events on the main UI thread
    ' by setting the SynchronizingObject property.
    ftp.SynchronizingObject = Me

    Dim ftp As New FtpClient()
     
    ftp.Connect( "localhost" )
    ftp.Login()

    Dim reply As String = ftp.SendCustomCommand( "HELP" )
    MessageBox.Show( reply )

    ftp.Disconnect()

    C# Copy Code

    using Xceed.Ftp;

    FtpClient ftp = new FtpClient();

    // When using FtpClient, you can instruct
    // the library to automatically redirect events on the main UI thread
    // by setting the SynchronizingObject property.
    ftp.SynchronizingObject = this;

    ftp.Connect( "localhost" );    
    ftp.Login();  

    string reply = ftp.SendCustomCommand( "HELP" );
    MessageBox.Show( reply );

    ftp.Disconnect();

    Asynchronous (non-blocking) demonstration

    AsyncFtpClient's methods now call the corresponding synchronous methods on a background thread. For this reason, the AsyncFtpClient class is now considered obsolete. It is therefore recommended to use FtpClient and assign a SynchronizingObject to its SynchronizingObject property to improve code readability.

    The following example demonstrates how to asynchronously send the "HELP" command to an FTP server using the BeginSendCustomCommand/ EndSendCustomCommand methods. A synchronous (non-blocking) demonstration is also available. 

    To clarify the code, instead of using callbacks, we will wait for completion of the operation before calling the matching "End" method. More information is available in the WinForms application and threading topic.

    VB.NET Copy Code

    Imports Xceed.Ftp

    Dim ftp As New AsyncFtpClient()
    Dim result As IAsyncResult = ftp.BeginConnect("localhost", Nothing, Nothing)

    While Not result.IsCompleted
      Application.DoEvents()
    End While

    ftp.EndConnect( result )
    result = ftp.BeginLogin( Nothing, Nothing )

    While Not result.IsCompleted
      Application.DoEvents()
    End While

    ftp.EndLogin( result )
    result = ftp.BeginSendCustomCommand( "HELP", Nothing, Nothing )

    While Not result.IsCompleted
      Application.DoEvents()
    End While

    Dim reply As String = ftp.EndSendCustomCommand(result)
    MessageBox.Show( reply )

    result = ftp.BeginDisconnect( Nothing, Nothing )

    While Not result.IsCompleted
      Application.DoEvents()
    End While

    ftp.EndDisconnect( result )

    C# Copy Code

    using Xceed.Ftp;

    AsyncFtpClient ftp = new AsyncFtpClient();

    IAsyncResult result = ftp.BeginConnect( "localhost", null, null );    

    while( !result.IsCompleted )
      Application.DoEvents();

    ftp.EndConnect( result );
    result = ftp.BeginLogin( null, null );

    while( !result.IsCompleted )
      Application.DoEvents();
      
    ftp.EndLogin( result );
    result = ftp.BeginSendCustomCommand( "HELP", null, null );

    while( !result.IsCompleted )
      Application.DoEvents();

    string reply = ftp.EndSendCustomCommand( result );
    MessageBox.Show( reply );
                                                     
    result = ftp.BeginDisconnect( null, null );

    while( !result.IsCompleted )
      Application.DoEvents();

    ftp.EndDisconnect( result );

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