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.NET FTP client
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Asynchronous operations
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Task-based Asynchronous Pattern (.NET 4.0 or later)
.NET 4.0 introduced the Task-based Asynchronous Pattern (TAP). Rebex SFTP supports it as well, just reference the assemblies for .NET 4.0 from your project.
// start async operation Task<SftpItemCollection> t = sftp.GetListAsync(); // set continuation method t.ContinueWith(GetListFinished);
' start async operation Dim t As Task(Of SftpItemCollection) = sftp.GetListAsync() ' set continuation method t.ContinueWith(AddressOf GetListFinished)
Sample asynchronous continuation method:
// this method is called when the async operation is completed private void GetListFinished(Task<SftpItemCollection> t) { // show error if any if (t.IsFaulted) { Console.WriteLine("An error occurred: {0}", t.Exception.ToString()); return; } // show cancel notification if (t.IsCanceled) { Console.WriteLine("Operation was canceled."); return; } // get operation result SftpItemCollection list = t.Result; // show result Console.WriteLine("Listed {0} item(s).", list.Count); }
' this is called when the async operation is completed Sub GetListFinished(ByVal t As Task(Of SftpItemCollection)) ' show error if any If t.IsFaulted Then Console.WriteLine("An error occurred: {0}", t.Exception.ToString()) Return End If ' show cancel notification If t.IsCanceled Then Console.WriteLine("Operation was canceled.") Return End If ' get operation result Dim list As SftpItemCollection = t.Result ' show result Console.WriteLine("Listed {0} item(s).", list.Count) End Sub
'await' operator support (.NET 4.5 or later)
.NET 4.5 introduced the 'await' operator, which makes writing asynchronous code more easy than ever before. Rebex SFTP supports it as well, just reference the assemblies for .NET 4.0 from your project.
private async void GetList() { try { // get list asynchronously SftpItemCollection list = await sftp.GetListAsync(); // show result Console.WriteLine("Listed {0} item(s).", list.Count); } catch (SftpException ex) { if (ex.Status == SftpExceptionStatus.OperationAborted) Console.WriteLine("Operation was canceled."); else Console.WriteLine("An error occurred: {0}.", ex.Message); } catch (Exception ex) { Console.WriteLine("An error occurred: {0}", ex.ToString()); } }
Public Async Sub GetList() Try ' get list asynchronously Dim list As SftpItemCollection = Await sftp.GetListAsync() ' show result Console.WriteLine("Listed {0} item(s).", list.Count) Catch ex As SftpException If ex.Status = SftpExceptionStatus.OperationAborted Then Console.WriteLine("Operation was canceled.") Else Console.WriteLine("An error occurred: {0}.", ex.Message) End If Catch ex As Exception Console.WriteLine("An error occurred: {0}", ex.ToString()) End Try End Sub
IAsyncResult pattern (Begin/End methods)
The Asynchronous Programming Model (APM) pattern, also known as IAsyncResult (or Begin/End) pattern, was introduced in .NET 1.0. When you reference Rebex assemblies for .NET 2.0 in your project, this is the pattern you can use.
// start async operation, specify callback IAsyncResult ar = sftp.BeginGetList(GetListFinished, null);
' start async operation, specify callback Dim ar = sftp.BeginGetList(AddressOf GetListFinished, Nothing)
Sample asynchronous callback method:
// this method is called when the Begin method is completed private void GetListFinished(IAsyncResult ar) { try { // get operation result SftpItemCollection list = sftp.EndGetList(ar); // show result Console.WriteLine("Listed {0} item(s).", list.Count); } catch (SftpException ex) { if (ex.Status == SftpExceptionStatus.OperationAborted) Console.WriteLine("Operation was canceled."); else Console.WriteLine("An error occurred: {0}.", ex.Message); } catch (Exception ex) { Console.WriteLine("An error occurred: {0}", ex.ToString()); } }
' this method is called when the Begin method is completed Sub GetListFinished(ByVal ar As IAsyncResult) Try ' get operation result Dim list As SftpItemCollection = sftp.EndGetList(ar) ' show result Console.WriteLine("Listed {0} item(s).", list.Count) Catch ex As SftpException If ex.Status = SftpExceptionStatus.OperationAborted Then Console.WriteLine("Operation was canceled.") Else Console.WriteLine("An error occurred: {0}.", ex.Message) End If Catch ex As Exception Console.WriteLine("An error occurred: {0}", ex.ToString()) End Try End Sub
Using IAsyncResult in .NET 4.0 or later
If you reference Rebex assemblies for .NET 4.0 or later from your project,
but still wish to use the old-style IAsyncResult asynchronous pattern, include the Rebex.Legacy
namespace.
By default, .NET 4.0 assemblies only present a Task-based pattern (TAP) asynchronous API.
Rebex.Legacy
namespace defines all the Begin/End methods as extension methods, making it possible to use
to easily port old code to .NET 4.0 or higher.
using Rebex.Legacy;
#If LEGACY Then Imports Rebex.Legacy #End If
SynchronizationContext support for events
When an asynchronous method on the Sftp
object raises an event, it's dispatched using
the synchronization context captured when
the operation was started.
This greatly simplifies writing GUI applications (Windows Forms and WPF) because all the events are raised on the applications GUI thread, eliminating the need
to explicitly marshal the calls using the Invoke
method.
If you need to disable this functionality, set Sftp.Settings.RaiseEventsFromCurrentThread
to true
. This will
cause all the events to be raised on the background operation's thread.
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