(.NET Core C#) Async Task Chain (another example)

Demonstrates using a task chain to run a sequence of FTP tasks asynchronously.

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// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
Chilkat.Global chilkatGlob = new Chilkat.Global();
bool success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
if (success != true) {
    Debug.WriteLine(chilkatGlob.LastErrorText);
    return;
}

Chilkat.Ftp2 ftp = new Chilkat.Ftp2();

ftp.Hostname = "ftp.someFtpServer.com";
ftp.Username = "****";
ftp.Password = "****";

// Connect and login to the FTP server.
success = ftp.Connect();
if (success != true) {
    Debug.WriteLine(ftp.LastErrorText);
    return;
}

Chilkat.TaskChain taskChain = new Chilkat.TaskChain();

// Create a task to change to the remote directory where the file will be uploaded.
Chilkat.Task task = ftp.ChangeRemoteDirAsync("junk");
if (ftp.LastMethodSuccess == false) {
    Debug.WriteLine(ftp.LastErrorText);
    return;
}

// Add this task to the task chain.
success = taskChain.Append(task);

// Create a task to upload a file.
string localFilename = "c:/temp/hamlet.xml";
string remoteFilename = "hamlet.xml";

task = ftp.PutFileAsync(localFilename,remoteFilename);
if (ftp.LastMethodSuccess == false) {
    Debug.WriteLine(ftp.LastErrorText);
    return;
}

// Add this task to the task chain.
success = taskChain.Append(task);

// Start the task chain running in a background thread.
// Each task is run one after the other (on the same background thread) until all tasks have completed.
// The task chain will stop at the first task that fails.
taskChain.StopOnFailedTask = true;
success = taskChain.Run();
if (!success) {
    Debug.WriteLine(taskChain.LastErrorText);
    return;
}

// The application is now free to do anything else
// while the FTP commands are being run...

// For this example, we'll simply sleep and periodically
// check to see if the taskchain if finished. 
while (taskChain.Finished != true) {

    // Sleep 100 ms.
    taskChain.SleepMs(100);

}

// A finished task chain could be one that was canceled, aborted, or truly finished.  

// If the task chain "completed", then it ran to completion.  A "completed" task will
// have a StatusInt equal to 7.   If the task finished, but was not completed, then it must've
// been aborted or canceled:
if (taskChain.StatusInt != 7) {
    Debug.WriteLine("Task did not complete.");
    Debug.WriteLine("task chain status: " + taskChain.Status);
    return;
}

// If we got to this point, the ChangeRemoteDir and PutFile were successful.
// We can visually verify by examining the LastErrorText that was recorded for each
// of these method calls..
int numTasks = taskChain.NumTasks;
int taskIdx = 0;

while ((taskIdx < numTasks)) {

    task = taskChain.GetTask(taskIdx);

    // Examine the status of this task, and the ResultErrorText
    // (the ResultErrorText is the ftp.LastErrorText captured for FTP method called by the task).
    // Everything should indicate success.
    Debug.WriteLine("task status: " + task.Status);
    Debug.WriteLine("task log: " + task.ResultErrorText);

    taskIdx = taskIdx + 1;
}

success = ftp.Disconnect();