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

> Chilkat 11.7.0 · language=activex · 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/activex/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**

```clike
Note:
For a specific major version, use "Chilkat.TaskChain.<major_version>", such as "Chilkat.TaskChain.10" for Chilkat v10.*.*
See Chilkat ActiveX Object Creation

(ASP)
set obj = Server.CreateObject("Chilkat.TaskChain")

(AutoIt)
$obj = ObjCreate("Chilkat.TaskChain")

(Visual Basic 6.0)
Dim obj As New ChilkatTaskChain

(VBScript)
set obj = CreateObject("Chilkat.TaskChain")

(VBA, such as Excel)
Dim obj As New ChilkatTaskChain
See How to Use ActiveX in Excel

(Delphi)
obj := TChilkatTaskChain.Create(Self);

(FoxPro)
loObject = CreateObject('Chilkat.TaskChain')

(Xbase++)
oObject := CreateObject("Chilkat.TaskChain")

(PowerBuilder)
lole_object = create oleobject
li_rc = lole_object.ConnectToNewObject("Chilkat.TaskChain")

(SQL Server)
EXEC @hr = sp_OACreate 'Chilkat.TaskChain', @obj OUT

(Javascript)
var obj = new ActiveXObject("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 ActiveX.

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` | `DebugLogFilePath As String` | read/write | If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. |
| `LastBinaryResult` | `LastBinaryResult As Variant (read-only)` | read-only | This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. |
| `LastErrorHtml` | `LastErrorHtml As String (read-only)` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `LastErrorText As String (read-only)` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `LastErrorXml As String (read-only)` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `LastMethodSuccess As Long` | read/write | Indicates the success or failure of the most recent method call: `1` means success, `0` means failure. |
| `LastStringResult` | `LastStringResult As String (read-only)` | read-only | In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. |
| `LastStringResultLen` | `LastStringResultLen As Long (read-only)` | read-only | The length, in characters, of the string contained in the LastStringResult property. |
| `VerboseLogging` | `VerboseLogging As Long` | read/write | If set to `1`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `Version As String (read-only)` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `Finished` | property, read-only | `Finished As Long (read-only)` |
| `HeartbeatMs` | property, read/write | `HeartbeatMs As Long` |
| `Inert` | property, read-only | `Inert As Long (read-only)` |
| `Live` | property, read-only | `Live As Long (read-only)` |
| `NumTasks` | property, read-only | `NumTasks As Long (read-only)` |
| `Status` | property, read-only | `Status As String (read-only)` |
| `StatusInt` | property, read-only | `StatusInt As Long (read-only)` |
| `StopOnFailedTask` | property, read/write | `StopOnFailedTask As Long` |
| `Append` | method | `Append(task As ChilkatTask) As Long` |
| `Cancel` | method | `Cancel() As Long` |
| `GetTask` | method | `GetTask(ByVal index As Long) As ChilkatTask` |
| `Run` | method | `Run() As Long` |
| `RunSynchronously` | method | `RunSynchronously() As Long` |
| `SleepMs` | method | `SleepMs(ByVal numMs As Long)` |
| `Wait` | method | `Wait(ByVal maxWaitMs As Long) As Long` |

## Properties

### TaskChain.Finished

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

```
Finished As Long (read-only)
```

`1` 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 · activex · TaskChain · HeartbeatMs · property · read/write · since 9.5.0.52`

```
HeartbeatMs As Long
```

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 · activex · TaskChain · Inert · property · read-only · since 9.5.0.52`

```
Inert As Long (read-only)
```

`1` 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 · activex · TaskChain · Live · property · read-only · since 9.5.0.52`

```
Live As Long (read-only)
```

`1` 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 · activex · TaskChain · NumTasks · property · read-only · since 9.5.0.52`

```
NumTasks As Long (read-only)
```

The number of tasks contained within the task chain.

### TaskChain.Status

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

```
Status As String (read-only)
```

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 · activex · TaskChain · StatusInt · property · read-only · since 9.5.0.52`

```
StatusInt As Long (read-only)
```

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 · activex · TaskChain · StopOnFailedTask · property · read/write · since 9.5.0.52`

```
StopOnFailedTask As Long
```

If `1` then stops execution of the task chain if any individual task fails. Task failure is defined by the standard LastMethodSuccess property. If `0`, then all of the tasks in the chain will be run even if some fail. The default value of this property is `1`.

## Methods

### TaskChain.Append

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

```
Append(task As ChilkatTask) As Long
```

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 1 for success, 0 for failure.

### TaskChain.Cancel

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

```
Cancel() As Long
```

Cancels execution of the asynchronous task chain.

Returns 1 for success, 0 for failure.

### TaskChain.GetTask

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

```
GetTask(ByVal index As Long) As ChilkatTask
```

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

Returns `Nothing` on failure

### TaskChain.Run

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

```
Run() As Long
```

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

Returns 1 for success, 0 for failure.

### TaskChain.RunSynchronously

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

```
RunSynchronously() As Long
```

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

Returns 1 for success, 0 for failure.

### TaskChain.SleepMs

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

```
SleepMs(ByVal numMs As Long)
```

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

### TaskChain.Wait

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

```
Wait(ByVal maxWaitMs As Long) As Long
```

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 (`0`) 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 `1`.

Returns 1 for success, 0 for failure.

## Events and callbacks

### TaskChain.AbortCheck (event)

`Chilkat 11.7.0 · activex · TaskChain · AbortCheck · event`

```
AbortCheck(abort As Long)
```

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.

**VB6 Event callback implementation:**

**Important:** Event callbacks from ***asynchronous method calls*** are generally not possible from the ActiveX. See [VB6 Event Callbacks](https://www.chilkatsoft.com/vb6_event_callbacks.asp)

```vb
Dim WithEvents myTaskchain As ChilkatTaskChain

Private Sub myTaskchain_AbortCheck(abort As Long)

	'Insert application code here.

End Sub
```

### TaskChain.PercentDone (event)

`Chilkat 11.7.0 · activex · TaskChain · PercentDone · event`

```
PercentDone(ByVal pctDone As Long, abort As Long)
```

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 `1`. This will cause the method to terminate and return a failure status or corresponding failure value.

**VB6 Event callback implementation:**

**Important:** Event callbacks from ***asynchronous method calls*** are generally not possible from the ActiveX. See [VB6 Event Callbacks](https://www.chilkatsoft.com/vb6_event_callbacks.asp)

```vb
Dim WithEvents myTaskchain As ChilkatTaskChain

Private Sub myTaskchain_PercentDone(ByVal pctDone As Long, abort As Long)

	'Insert application code here.

End Sub
```

### TaskChain.ProgressInfo (event)

`Chilkat 11.7.0 · activex · TaskChain · ProgressInfo · event`

```
ProgressInfo(ByVal name As String, ByVal value As String)
```

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.

**VB6 Event callback implementation:**

**Important:** Event callbacks from ***asynchronous method calls*** are generally not possible from the ActiveX. See [VB6 Event Callbacks](https://www.chilkatsoft.com/vb6_event_callbacks.asp)

```vb
Dim WithEvents myTaskchain As ChilkatTaskChain

Private Sub myTaskchain_ProgressInfo(ByVal name As String, ByVal value As String)

	'Insert application code here.

End Sub
```

### TaskChain.TaskCompleted (event)

`Chilkat 11.7.0 · activex · TaskChain · TaskCompleted · event`

```
TaskCompleted(task As ChilkatTask)
```

Called from the background thread when an asynchronous task completes.

**VB6 Event callback implementation:**

**Important:** Event callbacks from ***asynchronous method calls*** are generally not possible from the ActiveX. See [VB6 Event Callbacks](https://www.chilkatsoft.com/vb6_event_callbacks.asp)

```vb
Dim WithEvents myTaskchain As ChilkatTaskChain

Private Sub myTaskchain_TaskCompleted(task As ChilkatTask)

	'Insert application code here.

End Sub
```

## Related classes

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