Task

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

• A timeout property set to 0, indicating an infinite timeout.
• A hang occurring within an event callback in the application code.
• An internal bug in the Chilkat code causing the hang.

1 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.

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.

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

Determines if the in-memory progress info event log is kept. The default value is 0 and therefore no log is kept. To enable progress info logging, set this property equal to 1 (prior to running the task).

This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to 1. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.

In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.

The length, in characters, of the string contained in the LastStringResult property.

1 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.

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.

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.)

The LastErrorText for the task's asynchronous method.

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.

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.

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.

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.

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.

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.

If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Version of the component/library, such as "10.1.0"

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.

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.

Removes all entries from the progress info log.

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

Returns a zero-length byte array (as a Variant) on failure.
An empty array will have a UBound of -1 meaning 0 elements.

Returns the boolean result of the task.

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 a zero-length byte array (as a Variant) on failure.
An empty array will have a UBound of -1 meaning 0 elements.

Returns the integer result of the task.

Returns the string result of the task.

Returns Nothing on failure

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

Returns Nothing on failure

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

Returns Nothing on failure

Removes the Nth progress info log entry.

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

Returns 1 for success, 0 for failure.

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

Returns 1 for success, 0 for failure.

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.)

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 (0) 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 1.

Returns 1 for success, 0 for failure.

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

Dim WithEvents myTask As ChilkatTask

Private Sub myTask_AbortCheck(abort As Long)

	'Insert application code here.

End Sub

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

Dim WithEvents myTask As ChilkatTask

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

	'Insert application code here.

End Sub

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.

VB6 Event callback implementation:

Important: Event callbacks from asynchronous method calls are generally not possible from the ActiveX. See VB6 Event Callbacks

Dim WithEvents myTask As ChilkatTask

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

	'Insert application code here.

End Sub

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

Dim WithEvents myTask As ChilkatTask

Private Sub myTask_TaskCompleted(task As ChilkatTask)

	'Insert application code here.

End Sub