---
product: Chilkat
product_version: 11.7.0
language: vbnet
language_label: VB.NET
class: Task
license: bundle
deprecated: false
reference_html: https://www.chilkatsoft.com/refdoc/vbnetTaskRef.html
---
# Chilkat Task — VB.NET — v11.7.0

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

## Purpose

**Run, monitor, wait for, cancel, and retrieve results from asynchronous Chilkat operations.**

`Chilkat.Task` represents an asynchronous Chilkat method call. A task is typically returned by a Chilkat method whose name ends in `Async`. The task can be started, queued, monitored, waited on, canceled, and queried for its final result, including success status, error text, progress information, percent-done values, and typed return values such as strings, integers, booleans, or byte data.

**Async method results**

Receive a `Task` from Chilkat methods ending in `Async` and use it to control or observe the operation.

**Run or wait**

Start a task, run it synchronously when needed, wait for completion, or poll its status from application code.

**Status and progress**

Inspect whether the task is live, finished, inert, canceled, or failed, and monitor percent-done and progress log information.

**Cancel operations**

Request cancellation of a running task when the application needs to stop a long-running network, file, or cryptographic operation.

**Retrieve typed results**

After completion, retrieve the result as a boolean, integer, string, byte data, or other supported result form depending on the async method.

**Diagnostics**

Use `TaskSuccess`, `ResultErrorText`, `Status`, and `LastErrorText` to diagnose task execution and result-handling problems.

**Common pattern:** Call a Chilkat method ending in `Async`, start the returned `Task` with `Run`, optionally monitor status and progress, wait for completion, check `TaskSuccess`, then retrieve the final value using the result method that matches the original async operation. Use `Task` for one asynchronous operation; use `Chilkat.TaskChain` when multiple tasks should run in sequence.

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

## Object creation, unlocking and error handling

**Object Creation**

```vbnet
Dim obj As New Chilkat.Task()
```

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 VB.NET.

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. |
| `LastErrorHtml` | `LastErrorHtml As String (ReadOnly)` | read-only | Provides HTML-formatted information about the last called method or property. |
| `LastErrorText` | `LastErrorText As String (ReadOnly)` | read-only | Provides plain text information about the last called method or property. |
| `LastErrorXml` | `LastErrorXml As String (ReadOnly)` | read-only | Provides XML-formatted information about the last called method or property. |
| `LastMethodSuccess` | `LastMethodSuccess As Boolean` | read/write | Indicates the success or failure of the most recent method call: `True` means success, `False` means failure. |
| `VerboseLogging` | `VerboseLogging As Boolean` | read/write | If set to `True`, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. |
| `Version` | `Version As String (ReadOnly)` | read-only | Version of the component/library, such as "10.1.0" |

## Member index

| Member | Kind | Signature |
|---|---|---|
| `Finished` | property, read-only | `Finished As Boolean (ReadOnly)` |
| `HeartbeatMs` | property, read/write | `HeartbeatMs As Integer` |
| `Inert` | property, read-only | `Inert As Boolean (ReadOnly)` |
| `KeepProgressLog` | property, read/write | `KeepProgressLog As Boolean` |
| `Live` | property, read-only | `Live As Boolean (ReadOnly)` |
| `PercentDone` | property, read-only | `PercentDone As Integer (ReadOnly)` |
| `ProgressLogSize` | property, read-only | `ProgressLogSize As Integer (ReadOnly)` |
| `ResultErrorText` | property, read-only | `ResultErrorText As String (ReadOnly)` |
| `ResultType` | property, read-only | `ResultType As String (ReadOnly)` |
| `Status` | property, read-only | `Status As String (ReadOnly)` |
| `StatusInt` | property, read-only | `StatusInt As Integer (ReadOnly)` |
| `TaskId` | property, read-only | `TaskId As Integer (ReadOnly)` |
| `TaskSuccess` | property, read-only | `TaskSuccess As Boolean (ReadOnly)` |
| `UserData` | property, read/write | `UserData As String` |
| `Cancel` | method | `Function Cancel() As Boolean` |
| `ClearProgressLog` | method | `Sub ClearProgressLog()` |
| `CopyResultBytes` | method | `Function CopyResultBytes() As Byte()` |
| `GetResultBool` | method | `Function GetResultBool() As Boolean` |
| `GetResultBytes` | method | `Function GetResultBytes() As Byte()` |
| `GetResultInt` | method | `Function GetResultInt() As Integer` |
| `GetResultString` | method | `Function GetResultString() As String` |
| `ProgressInfoName` | method | `Function ProgressInfoName(ByVal index As Integer) As String` |
| `ProgressInfoValue` | method | `Function ProgressInfoValue(ByVal index As Integer) As String` |
| `RemoveProgressInfo` | method | `Sub RemoveProgressInfo(ByVal index As Integer)` |
| `Run` | method | `Function Run() As Boolean` |
| `RunSynchronously` | method | `Function RunSynchronously() As Boolean` |
| `SleepMs` | method | `Sub SleepMs(ByVal numMs As Integer)` |
| `Wait` | method | `Function Wait(ByVal maxWaitMs As Integer) As Boolean` |

## Properties

### Task.Finished

`Chilkat 11.7.0 · vbnet · Task · Finished · property · read-only · since 9.5.0.52`

```vbnet
Finished As Boolean (ReadOnly)
```

`True` if the task status is `canceled`, `aborted`, or `completed`. A task 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.

### Task.HeartbeatMs

`Chilkat 11.7.0 · vbnet · Task · HeartbeatMs · property · read/write · since 9.5.0.52`

```vbnet
HeartbeatMs As Integer
```

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 running in a background thread (in one of the thread pool threads) does not fire events. The task's event callbacks pertain only to the Wait method.

### Task.Inert

`Chilkat 11.7.0 · vbnet · Task · Inert · property · read-only · since 9.5.0.52`

```vbnet
Inert As Boolean (ReadOnly)
```

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

### Task.KeepProgressLog

`Chilkat 11.7.0 · vbnet · Task · KeepProgressLog · property · read/write · since 9.5.0.52`

```vbnet
KeepProgressLog As Boolean
```

Determines if the in-memory progress info event log is kept. The default value is `False` and therefore no log is kept. To enable progress info logging, set this property equal to `True` (prior to running the task).

### Task.Live

`Chilkat 11.7.0 · vbnet · Task · Live · property · read-only · since 9.5.0.52`

```vbnet
Live As Boolean (ReadOnly)
```

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

### Task.PercentDone

`Chilkat 11.7.0 · vbnet · Task · PercentDone · property · read-only · since 9.5.0.52`

```vbnet
PercentDone As Integer (ReadOnly)
```

Indicates the percent completion while the task is running. The percent completed information is only available in cases where it is possible to know the percentage completed. For some methods, it is never possible to know, such as for methods that establish TCP or TLS connections. For other methods it is always possible to know -- such as for sending email (because the size of the email to be sent is already known). For some methods, it may or may not be possible to know the percent completed. For example, if an HTTP response is `chunked`, there is no Content-Length header and therefore the receiver has no knowledge of the size of the forthcoming response body.

Also, the value of the PercentDoneScale property of the asynchronous method's object determines the scale, such as 0 to 100, or 0 to 1000, etc.

### Task.ProgressLogSize

`Chilkat 11.7.0 · vbnet · Task · ProgressLogSize · property · read-only · since 9.5.0.52`

```vbnet
ProgressLogSize As Integer (ReadOnly)
```

What would normally be a ProgressInfo event callback (assuming Chilkat supports event callbacks for this language) is instead saved to an in-memory progress log that can be examined and pruned while the task is still running. This property returns the number of progress log entries that are currently available. (Note: the progress log is only kept if the KeepProgressLog property is turned on. By default, the KeepProgressLog is turned off.)

### Task.ResultErrorText

`Chilkat 11.7.0 · vbnet · Task · ResultErrorText · property · read-only · since 9.5.0.52`

```vbnet
ResultErrorText As String (ReadOnly)
```

The LastErrorText for the task's asynchronous method.

### Task.ResultType

`Chilkat 11.7.0 · vbnet · Task · ResultType · property · read-only · since 9.5.0.52`

```vbnet
ResultType As String (ReadOnly)
```

Indicates the data type of the task's result. This property is only available after the task has completed. Possible values are `bool`, `int`, `string`, `bytes`, `object`, and `void`. For example, if the result data type is `bool`, then call GetResultBool to get the boolean result of the underlying asynchronous method.

For example, if the synchronous version of the method returned a boolean, then in the asynchronous version of the method, the boolean return value is made available via the GetResultBool method.

### Task.Status

`Chilkat 11.7.0 · vbnet · Task · Status · property · read-only · since 9.5.0.52`

```vbnet
Status As String (ReadOnly)
```

The current status of the task. Possible values are:

- `empty` -- The method call and arguments are not yet loaded into the task object. This can only happen if a task was explicitly created instead of being returned by a method ending in `Async`.
- `loaded` -- The method call and arguments are loaded into the task object.
- `queued` -- The task is in the thread pool's queue of tasks awaiting to be run.
- `running` -- The task is currently running.
- `canceled` -- The task was canceled before it entered the `running` state.
- `aborted` -- The task was canceled while it was in the running state.
- `completed` -- The task completed. The success or failure depends on the semantics of the method call and the value of the result.

### Task.StatusInt

`Chilkat 11.7.0 · vbnet · Task · StatusInt · property · read-only · since 9.5.0.52`

```vbnet
StatusInt As Integer (ReadOnly)
```

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

- **1** -- The method call and arguments are not yet loaded into the task object. This can only happen if a task was explicitly created instead of being returned by a method ending in `Async`.
- **2** -- The method call and arguments are loaded into the task object.
- **3** -- The task is in the thread pool's queue of tasks awaiting to be run.
- **4** -- The task is currently running.
- **5** -- The task was canceled before it entered the `running` state.
- **6** -- The task was canceled while it was in the running state.
- **7** -- The task completed. The success or failure depends on the semantics of the method call and the value of the result.

### Task.TaskId

`Chilkat 11.7.0 · vbnet · Task · TaskId · property · read-only · since 9.5.0.52`

```vbnet
TaskId As Integer (ReadOnly)
```

A unique integer ID assigned to this task. The purpose of this property is to help an application identify the task if a TaskCompleted event callback is used.

### Task.TaskSuccess

`Chilkat 11.7.0 · vbnet · Task · TaskSuccess · property · read-only · since 9.5.0.52`

```vbnet
TaskSuccess As Boolean (ReadOnly)
```

This is the value of the LastMethodSuccess property of the underlying task object. This property is only valid for those methods where the LastMethodSuccess property would be valid had the method been called synchronously.

**Important:** This property is only meaningful for cases where the underlying method call has a non-boolean return value (such as for methods that return strings, other Chilkat objects, or integers). If the underlying method call returns a boolean, then call the GetResultBool() method instead to get the boolean return value.

### Task.UserData

`Chilkat 11.7.0 · vbnet · Task · UserData · property · read/write · since 9.5.0.52`

```vbnet
UserData As String
```

An application may use this property to attach some user-specific information with the task, which may be useful if a TaskCompleted event callback is used.

## Methods

### Task.Cancel

`Chilkat 11.7.0 · vbnet · Task · Cancel · method · since 9.5.0.52`

```vbnet
Function Cancel() As Boolean
```

Marks an asynchronous task for cancellation. The expected behavior depends on the current status of the task as described here:

- **`loaded`** - If the task has been loaded but has not yet been queued to run in the thread pool, then there is nothing to do. (There is nothing to cancel because the task's Run method has not yet been called.) The task will remain in the `loaded` state.
- **`queued`** - The task is marked for cancellation, is dequeued, and will not run. The task's status changes immediately to `canceled`.
- **`running`** - The already-running task is marked for cancellation. The task's status will **eventually** change to `aborted` when the asynchronous method returns. At that point in time, the ResultErrorText property will contain the `LastErrorText` of the method call. In the case where a task is marked for cancellation just at the time it's completing, the task status may instead change to `completed`.
- **`canceled`, `aborted`, `completed`** - In these cases the task has already finished, and there will be no change in status.

Cancel returns `True` if the task was in the `queued` or `running` state when it was marked for cancellation. Cancel returns `False` if the task was in any other state.

**Important:** Calling the Cancel method marks a task for cancellation. It sets a flag in memory that the running task will soon notice and then abort. It is important to realize that your application is likely calling Cancel from the main UI thread, whereas the asynchronous task is running in a background thread. If the task was in the `running` state when Cancel was called, it will still be in the `running` state when Cancel returns. It will take a short amount of time until the task actually aborts. This is because operating systems schedule threads in time slices, and the thread needs one or more time slices to notice the cancellation flag and abort. After calling Cancel, your application might wish to call the Wait method to wait until the task has actually aborted, or it could periodically check the task's status and then react once the status changes to `aborted`.

### Task.ClearProgressLog

`Chilkat 11.7.0 · vbnet · Task · ClearProgressLog · method · since 9.5.0.52`

```vbnet
Sub ClearProgressLog()
```

Removes all entries from the progress info log.

### Task.CopyResultBytes

`Chilkat 11.7.0 · vbnet · Task · CopyResultBytes · method · since 9.5.0.52`

```vbnet
Function CopyResultBytes() As Byte()
```

Returns the binary bytes result of the task. The bytes are copied to the caller.

Returns an empty byte array on failure

### Task.GetResultBool

`Chilkat 11.7.0 · vbnet · Task · GetResultBool · method · since 9.5.0.52`

```vbnet
Function GetResultBool() As Boolean
```

Returns the boolean result of the task.

### Task.GetResultBytes

`Chilkat 11.7.0 · vbnet · Task · GetResultBytes · method · since 9.5.0.52`

```vbnet
Function GetResultBytes() As Byte()
```

Returns the binary bytes result of the task. The bytes are transferred to the caller, not copied. Call CopyResultBytes instead to copy the result bytes.

Returns an empty byte array on failure

### Task.GetResultInt

`Chilkat 11.7.0 · vbnet · Task · GetResultInt · method · since 9.5.0.52`

```vbnet
Function GetResultInt() As Integer
```

Returns the integer result of the task.

### Task.GetResultString

`Chilkat 11.7.0 · vbnet · Task · GetResultString · method · since 9.5.0.52`

```vbnet
Function GetResultString() As String
```

Returns the string result of the task.

Returns `Nothing` on failure

### Task.ProgressInfoName

`Chilkat 11.7.0 · vbnet · Task · ProgressInfoName · method · since 9.5.0.52`

```vbnet
Function ProgressInfoName(ByVal index As Integer) As String
```

Returns the name of the Nth progress info event logged. The 1st entry is at index 0.

Returns `Nothing` on failure

### Task.ProgressInfoValue

`Chilkat 11.7.0 · vbnet · Task · ProgressInfoValue · method · since 9.5.0.52`

```vbnet
Function ProgressInfoValue(ByVal index As Integer) As String
```

Returns the value of the Nth progress info event logged. The 1st entry is at index 0.

Returns `Nothing` on failure

### Task.RemoveProgressInfo

`Chilkat 11.7.0 · vbnet · Task · RemoveProgressInfo · method · since 9.5.0.52`

```vbnet
Sub RemoveProgressInfo(ByVal index As Integer)
```

Removes the Nth progress info log entry.

### Task.Run

`Chilkat 11.7.0 · vbnet · Task · Run · method · since 9.5.0.52`

```vbnet
Function Run() As Boolean
```

Queues the task to run on the internal Chilkat thread pool.

Returns True for success, False for failure.

### Task.RunSynchronously

`Chilkat 11.7.0 · vbnet · Task · RunSynchronously · method · since 9.5.0.52`

```vbnet
Function RunSynchronously() As Boolean
```

Runs the task synchronously. Then this method returns after the task has been run.

Returns True for success, False for failure.

### Task.SleepMs

`Chilkat 11.7.0 · vbnet · Task · SleepMs · method · since 9.5.0.52`

```vbnet
Sub SleepMs(ByVal numMs As Integer)
```

Convenience method to force the calling thread to sleep for a number of milliseconds. (This does not cause the task's background thread to sleep.)

### Task.Wait

`Chilkat 11.7.0 · vbnet · Task · Wait · method · since 9.5.0.52`

```vbnet
Function Wait(ByVal maxWaitMs As Integer) As Boolean
```

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

Returns True for success, False for failure.

## Events and callbacks

### Task.AbortCheck (event)

`Chilkat 11.7.0 · vbnet · Task · AbortCheck · event`

```vbnet
Event 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.

Event arguments are passed in a Chilkat.AbortCheckEventArgs object.

**Event callback implementation:**

Declare the object with the **WithEvents** keyword, then write a Sub with a **Handles** clause for the event. Visual Basic connects the two automatically, so no AddHandler call is needed.

```vbnet
Dim WithEvents task As Chilkat.Task

Private Sub task_OnAbortCheck(sender As Object, args As Chilkat.AbortCheckEventArgs) Handles task.OnAbortCheck

    ' application code goes here.

End Sub
```

### Task.PercentDone (event)

`Chilkat 11.7.0 · vbnet · Task · PercentDone · event`

```vbnet
Event 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.

Event arguments are passed in a Chilkat.PercentDoneEventArgs object.

**Event callback implementation:**

Declare the object with the **WithEvents** keyword, then write a Sub with a **Handles** clause for the event. Visual Basic connects the two automatically, so no AddHandler call is needed.

```vbnet
Dim WithEvents task As Chilkat.Task

Private Sub task_OnPercentDone(sender As Object, args As Chilkat.PercentDoneEventArgs) Handles task.OnPercentDone

    ' application code goes here.

End Sub
```

### Task.ProgressInfo (event)

`Chilkat 11.7.0 · vbnet · Task · ProgressInfo · event`

```vbnet
Event 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.

Event arguments are passed in a Chilkat.ProgressInfoEventArgs object.

**Event callback implementation:**

Declare the object with the **WithEvents** keyword, then write a Sub with a **Handles** clause for the event. Visual Basic connects the two automatically, so no AddHandler call is needed.

```vbnet
Dim WithEvents task As Chilkat.Task

Private Sub task_OnProgressInfo(sender As Object, args As Chilkat.ProgressInfoEventArgs) Handles task.OnProgressInfo

    ' application code goes here.

End Sub
```

### Task.TaskCompleted (event)

`Chilkat 11.7.0 · vbnet · Task · TaskCompleted · event`

```vbnet
Event OnTaskCompleted
```

Called from the background thread when an asynchronous task completes.

Event arguments are passed in a Chilkat.TaskCompletedEventArgs object.

**Event callback implementation:**

Declare the object with the **WithEvents** keyword, then write a Sub with a **Handles** clause for the event. Visual Basic connects the two automatically, so no AddHandler call is needed.

```vbnet
Dim WithEvents task As Chilkat.Task

Private Sub task_OnTaskCompleted(sender As Object, args As Chilkat.TaskCompletedEventArgs) Handles task.OnTaskCompleted

    ' application code goes here.

End Sub
```