---
product: Chilkat
product_version: 11.7.0
language: csharp
language_label: C#
class: TaskChain
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/csTaskChainRef.html
---
# Chilkat TaskChain — C# — v11.7.0

> Chilkat 11.7.0 · language=csharp · class=TaskChain
> Other versions: replace `11.7.0` in this URL. Other languages: `https://www.chilkatsoft.com/ai-docs/v/11.7.0/<lang>/classes/TaskChain.md`.
> Language-wide rules (install, unlock, error model, strings/bytes): `https://www.chilkatsoft.com/ai-docs/v/11.7.0/csharp/guide.md`.

## Purpose

**Run multiple asynchronous Chilkat tasks in a defined sequence.**

`Chilkat.TaskChain` manages a sequence of `Chilkat.Task` objects and runs them one after another. It is useful when multiple asynchronous Chilkat operations must execute in a predictable order while still allowing the entire chain to be started, monitored, waited on, canceled, or run synchronously. A task chain can stop when a task fails, or continue depending on the configured behavior.

**Sequential async workflow**

Append multiple `Task` objects and run them in order when one operation must finish before the next begins.

**Chain-level execution**

Start the entire chain, run it synchronously, wait for completion, or cancel the chain as a single coordinated operation.

**Monitor progress and status**

Inspect whether the chain is live, finished, inert, canceled, failed, or still running.

**Access individual tasks**

Retrieve tasks by index after execution to inspect each task's status, success flag, error text, and result.

**Stop-on-failure control**

Use `StopOnFailedTask` to control whether the chain stops at the first failed task or continues to later tasks.

**Diagnostics**

Use task and chain status information together with `LastErrorText` and each task's result details to troubleshoot ordered async workflows.

**Common pattern:** Create the individual async tasks, append them to a `TaskChain` in the required order, set `StopOnFailedTask` as appropriate, run the chain, wait for completion, then inspect each task's success status and result. Use `TaskChain` when operations must run sequentially; use individual `Task` objects when each async operation can be managed on its own.

For an extended overview, see [TaskChain Class Overview](https://www.chilkatsoft.com/taskchain_class_overview.asp).

## Object creation, unlocking and error handling

**Object Creation**

```csharp
Chilkat.TaskChain obj = new Chilkat.TaskChain();
```

Call `Global.UnlockBundle` once at the start of the program, before using this or any other Chilkat class. Any string unlocks a fully functional 30-day trial; a purchased unlock code is used in production. See `guide.md` for the exact code in C#.

Minimal complete program:

```csharp
// Required once per process. Any string unlocks a 30-day trial; use your purchased code in production.
Chilkat.Global glob = new Chilkat.Global();
if (!glob.UnlockBundle("Anything for 30-day trial"))
{
    Console.WriteLine(glob.LastErrorText);
    return;
}

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

How failure is reported depends on the method's return type and is stated in the note under each method below. In every case the diagnostic text is in the `LastErrorText` property of the object whose method was called.

## Members common to every Chilkat class

Documented once per language in `common-members.md`; listed here so this page is self-contained.

| Property | Signature | Access | Meaning |
|---|---|---|---|
| `DebugLogFilePath` | `public string DebugLogFilePath {get; set; }` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastErrorHtml` | `public string LastErrorHtml {get; }` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `public string LastErrorText {get; }` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `public string LastErrorXml {get; }` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `public bool LastMethodSuccess {get; set; }` | read/write | Indicates the success or failure of the most recent method call: `true` means success, `false` means failure. |
| `VerboseLogging` | `public bool VerboseLogging {get; set; }` | read/write | If set to `true`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `public string Version {get; }` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `Finished` | property, read-only | `public bool Finished {get; }` |
| `HeartbeatMs` | property, read/write | `public int HeartbeatMs {get; set; }` |
| `Inert` | property, read-only | `public bool Inert {get; }` |
| `Live` | property, read-only | `public bool Live {get; }` |
| `NumTasks` | property, read-only | `public int NumTasks {get; }` |
| `Status` | property, read-only | `public string Status {get; }` |
| `StatusInt` | property, read-only | `public int StatusInt {get; }` |
| `StopOnFailedTask` | property, read/write | `public bool StopOnFailedTask {get; set; }` |
| `Append` | method | `public bool Append(Task task);` |
| `Cancel` | method | `public bool Cancel();` |
| `GetTask` | method | `public Task GetTask(int index);` |
| `Run` | method | `public bool Run();` |
| `RunSynchronously` | method | `public bool RunSynchronously();` |
| `SleepMs` | method | `public void SleepMs(int numMs);` |
| `Wait` | method | `public bool Wait(int maxWaitMs);` |

## Properties

### TaskChain.Finished

`Chilkat 11.7.0 · csharp · TaskChain · Finished · property · read-only · since 9.5.0.52`

```csharp
public bool Finished {get; }
```

`true` if the task status is `canceled`, `aborted`, or `completed`. A task chain can only reach the `canceled` status if it was activated via the Run method, made it onto the internal thread pool thread's queue, was waiting for a pool thread to become available, and was then canceled prior to the task actually starting.

### TaskChain.HeartbeatMs

`Chilkat 11.7.0 · csharp · TaskChain · HeartbeatMs · property · read/write · since 9.5.0.52`

```csharp
public int HeartbeatMs {get; set; }
```

The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort the Wait method. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire. **Note:** An asynchronous task chain running in a background thread (in one of the thread pool threads) does not fire events. The task chain's event callbacks pertain only to the Wait method.

### TaskChain.Inert

`Chilkat 11.7.0 · csharp · TaskChain · Inert · property · read-only · since 9.5.0.52`

```csharp
public bool Inert {get; }
```

`true` if the task status is `empty` or `loaded`. When a task chain is inert, it has been loaded but is not scheduled to run yet.

### TaskChain.Live

`Chilkat 11.7.0 · csharp · TaskChain · Live · property · read-only · since 9.5.0.52`

```csharp
public bool Live {get; }
```

`true` if the task status is `queued` or `running`. When a task chain is live, it is either already running, or is on the thread pool thread's queue waiting for a thread to become available.

### TaskChain.NumTasks

`Chilkat 11.7.0 · csharp · TaskChain · NumTasks · property · read-only · since 9.5.0.52`

```csharp
public int NumTasks {get; }
```

The number of tasks contained within the task chain.

### TaskChain.Status

`Chilkat 11.7.0 · csharp · TaskChain · Status · property · read-only · since 9.5.0.52`

```csharp
public string Status {get; }
```

The current status of the task chain. Possible values are:

- `empty` -- No tasks have yet been appended to the task chain.
- `loaded` -- The task chain has been loaded (appended) with one or more task objects.
- `queued` -- The task chain is in the thread pool's queue of tasks awaiting to be run.
- `running` -- The task chain is currently running.
- `canceled` -- The task chain was canceled before it entered the `running` state.
- `aborted` -- The task chain was canceled while it was in the running state.
- `completed` -- The task chain completed.

### TaskChain.StatusInt

`Chilkat 11.7.0 · csharp · TaskChain · StatusInt · property · read-only · since 9.5.0.52`

```csharp
public int StatusInt {get; }
```

The current status of the task as an integer value. Possible values are:

- **1** -- `empty` -- No tasks have yet been appended to the task chain.
- **2** -- `loaded` -- The task chain has been loaded (appended) with one or more task objects.
- **3** -- `queued` -- The task chain is in the thread pool's queue of tasks awaiting to be run.
- **4** -- `running` -- The task chain is currently running.
- **5** -- `canceled` -- The task chain was canceled before it entered the `running` state.
- **6** -- `aborted` -- The task chain was canceled while it was in the running state.
- **7** -- `completed` -- The task chain completed.

### TaskChain.StopOnFailedTask

`Chilkat 11.7.0 · csharp · TaskChain · StopOnFailedTask · property · read/write · since 9.5.0.52`

```csharp
public bool StopOnFailedTask {get; set; }
```

If `true` then stops execution of the task chain if any individual task fails. Task failure is defined by the standard LastMethodSuccess property. If `false`, then all of the tasks in the chain will be run even if some fail. The default value of this property is `true`.

## Methods

### TaskChain.Append

`Chilkat 11.7.0 · csharp · TaskChain · Append · method · since 9.5.0.52`

```csharp
public bool Append(Task task);
```

Appends a task to the task chain. Can fail if the task is already part of another chain. (A task can only be part of a single chain.)

Returns true for success, false for failure.

### TaskChain.Cancel

`Chilkat 11.7.0 · csharp · TaskChain · Cancel · method · since 9.5.0.52`

```csharp
public bool Cancel();
```

Cancels execution of the asynchronous task chain.

Returns true for success, false for failure.

### TaskChain.GetTask

`Chilkat 11.7.0 · csharp · TaskChain · GetTask · method · since 9.5.0.52`

```csharp
public Task GetTask(int index);
```

Returns the Nth task in the chain. The 1st task is at index 0.

Returns `null` on failure

### TaskChain.Run

`Chilkat 11.7.0 · csharp · TaskChain · Run · method · since 9.5.0.52`

```csharp
public bool Run();
```

Queues the task chain to run on the internal Chilkat thread pool. Each task in the chain will run, one after the other.

Returns true for success, false for failure.

### TaskChain.RunSynchronously

`Chilkat 11.7.0 · csharp · TaskChain · RunSynchronously · method · since 9.5.0.52`

```csharp
public bool RunSynchronously();
```

Runs the task chain synchronously. Then this method returns after all the tasks in the chain have been run.

Returns true for success, false for failure.

### TaskChain.SleepMs

`Chilkat 11.7.0 · csharp · TaskChain · SleepMs · method · since 9.5.0.52`

```csharp
public void SleepMs(int numMs);
```

Convenience method to force the calling thread to sleep for a number of milliseconds.

### TaskChain.Wait

`Chilkat 11.7.0 · csharp · TaskChain · Wait · method · since 9.5.0.52`

```csharp
public bool Wait(int maxWaitMs);
```

Waits for the task chain to complete. Returns when all of the tasks in the chain have completed, or after `maxWaitMs` milliseconds have elapsed. (A `maxWaitMs` value of 0 is to wait indefinitely.) Returns (`false`) if the task chain has not yet been started by calling the Run method, or if the `maxWaitMs` expired. If the task chain completed, was already completed, was canceled, or aborted, then this method returns `true`.

Returns true for success, false for failure.

## Events and callbacks

### TaskChain.AbortCheck (event)

`Chilkat 11.7.0 · csharp · TaskChain · AbortCheck · event`

```csharp
public event AbortCheckEventHandler OnAbortCheck;
```

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the `HeartbeatMs` property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

### Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

**Event callback implementation:**

```csharp
private void taskchain_OnAbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
taskchain.OnAbortCheck += taskchain_OnAbortCheck;
```

### Chilkat .NET Core Event Implementation

**Event callback implementation:**

```csharp
public void handleAbortCheck(out bool abort)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
// ...
Chilkat.TaskChain.AbortCheck abortCheck = new Chilkat.TaskChain.AbortCheck(handleAbortCheck);
taskchain.setAbortCheckCb(abortCheck);
```

### TaskChain.PercentDone (event)

`Chilkat 11.7.0 · csharp · TaskChain · PercentDone · event`

```csharp
public event PercentDoneEventHandler OnPercentDone;
```

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The `pctDone` argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have `pctDone` equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an `AbortCheck` event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the `abort` output argument to `true`. This will cause the method to terminate and return a failure status or corresponding failure value.

### Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

**Event callback implementation:**

```csharp
private void taskchain_OnPercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
taskchain.OnPercentDone += taskchain_OnPercentDone;
```

### Chilkat .NET Core Event Implementation

**Event callback implementation:**

```csharp
public void handlePercentDone(int pctDone, out bool abort)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
// ...
Chilkat.TaskChain.PercentDone percentDone = new Chilkat.TaskChain.PercentDone(handlePercentDone);
taskchain.setPercentDoneCb(percentDone);
```

### TaskChain.ProgressInfo (event)

`Chilkat 11.7.0 · csharp · TaskChain · ProgressInfo · event`

```csharp
public event ProgressInfoEventHandler OnProgressInfo;
```

This event callback provides `tag name`/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

Note: Some Chilkat methods don't fire any ProgressInfo events.

### Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

**Event callback implementation:**

```csharp
private void taskchain_OnProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
taskchain.OnProgressInfo += taskchain_OnProgressInfo;
```

### Chilkat .NET Core Event Implementation

**Event callback implementation:**

```csharp
public void handleProgressInfo(string name, string value)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
// ...
Chilkat.TaskChain.ProgressInfo progressInfo = new Chilkat.TaskChain.ProgressInfo(handleProgressInfo);
taskchain.setProgressInfoCb(progressInfo);
```

### TaskChain.TaskCompleted (event)

`Chilkat 11.7.0 · csharp · TaskChain · TaskCompleted · event`

```csharp
public event TaskCompletedEventHandler OnTaskCompleted;
```

Called from the background thread when an asynchronous task completes.

### Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

**Event callback implementation:**

```csharp
private void taskchain_OnTaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
taskchain.OnTaskCompleted += taskchain_OnTaskCompleted;
```

### Chilkat .NET Core Event Implementation

**Event callback implementation:**

```csharp
public void handleTaskIdCompleted(int taskId)
	{
	    // application code goes here.
	}
```

**To add an event handler:**

```csharp
Chilkat.TaskChain taskchain = new Chilkat.TaskChain();
// ...
Chilkat.TaskChain.TaskIdCompleted taskIdCompleted = new Chilkat.TaskChain.TaskIdCompleted(handleTaskIdCompleted);
taskchain.setTaskIdCompletedCb(taskIdCompleted);
```

## Related classes

[`Task`](https://www.chilkatsoft.com/ai-docs/v/11.7.0/csharp/classes/Task.md)