File Transfer sample (.NET)

Overview

This sample demostrates some of the Remoting SDK fundamentals: complex types, arrays and binary data transfer.

Getting started

• Compile the entire solution.
• Run the server application.
• Run the client application.
• Set a directory in the client's edit box and click Go; see the list view below populated with the selected directory contents.
• Select a file to transfer and click Download File. Note: This sample is for illustration purposes only and contains no protective code against too large, inaccessible files and so on.

Examine the code

The server

• See the implementation of the GetDirectory method. Notice how the file information is packed into the array of TFileInfo structures, the structure is defined in the RODL.

public virtual TFileInfo[] GetDirectory(string FullPath) 
{
    DirectoryInfo dirinfo = new DirectoryInfo(FullPath);
    // Get Directories ...
    DirectoryInfo[] directories = dirinfo.GetDirectories(); 
    // Get Files ...
    FileInfo[] files = dirinfo.GetFiles("*.*");
    int folderCount = directories.GetLength(0);
    int fileCount = files.GetLength(0);
    int itemsCount = folderCount + fileCount;
    int i;
    
    // 
    TFileInfo[] result = new TFileInfo[itemsCount];
    for (i = 0; i < folderCount; i++)
    {
        result[i] = new TFileInfo();
        result[i].TypeName = "Folder";
        result[i].FileName = directories[i].Name;
        result[i].Size = 0;

    }
    for (i = 0; i < fileCount; i++)
    {
        result[i + folderCount] = new TFileInfo();
        result[i + folderCount].TypeName = files[i].Extension;
        result[i + folderCount].FileName = files[i].Name;
        result[i + folderCount].Size = files[i].Length;
    }               
    return result;
}

• See the implementation of the ReadFile method that prepares the Binary object.

public virtual RemObjects.SDK.Types.Binary ReadFile(string FileName) 
{
    Binary responsedata = new Binary();
    using (FileStream file = new FileStream(FileName, FileMode.Open, FileAccess.Read, FileShare.Read))
    {
        // ...
        StreamHelpers.CopyFromStreamToStream(file, responsedata);
        return responsedata;
    }
}

The client

• Creating the service proxy that persists during the application life time:

private void Form1_Load(object sender, System.EventArgs e)
{
    fFileTransfer = CoFileTransferService.Create(clientMessage, clientChannel);
}

• See how the array of structures sent by the server is consumed on the client side:

private void getFolderContents(String remotePath)
{
    // ...
    try
    {
        // ...
        TFileInfo[] files = fFileTransfer.GetDirectory(remotePath);
        foreach (TFileInfo file in files)
        {
            name = file.FileName;
            size = file.Size.ToString("#,#");
            typename = file.TypeName;
            // ...
        }

    }
    catch (Exception ex)
    {
        // Processing the exception that can happen during the remote call
        MessageBox.Show("The following exception occured:\n\n" + ex.Message);
    }
}

• Retrieving the binary data, i.e. the file contents:

private void bDownload_Click(object sender, System.EventArgs e)
{
    // ...
    try
    {
        // ...
            Binary lResult = fFileTransfer.ReadFile(remoteFileName);
            if (lResult != null)
            {
                // The file contents are retrieved
            }
        }
    }
    catch (Exception ex)
    {
        // Processing the exception that can happen during the remote call
        MessageBox.Show("The following exception occured:\n\n" + ex.Message);
    }
}

• Pay attention to the event handlers attached to the client channel. They allow to monitor data transfers through the channel, which is especially useful when transferring large data portions:

private void fClient_OnTransferStart(object aSender, RemObjects.SDK.TransferStartEventArgs ea)
{
    // ...
}

private void fClient_OnTransferProgress(object aSender, RemObjects.SDK.TransferProgressEventArgs ea)
{
    // ...
}

private void fClient_OnTransferEnd(object aSender, RemObjects.SDK.TransferEndEventArgs ea)
{
    // ...
}