(SQL Server) Starting an Asynchronous Task

Chilkat methods that have a name ending in "Async" return a task object. The task object can be run asynchronously on Chilkat's background thread pool. The purpose of this example is to demonstrate how a Task is started via the Run method. It also demonstrates how an application can check on the status of the task, and get the task return value. See the online reference documentation for the full details of the task and task chain objects. Also see the "Task" category on example-code.com for more examples.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- All Chilkat classes can be unlocked at once at the beginning of a program
    -- by calling UnlockBundle.  It requires a Bundle unlock code.
    DECLARE @chilkatGlob int
    -- Use "Chilkat_9_5_0.Global" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Global', @chilkatGlob OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @success int
    EXEC sp_OAMethod @chilkatGlob, 'UnlockBundle', @success OUT, 'Anything for 30-day trial.'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @chilkatGlob, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @chilkatGlob
        RETURN
      END

    DECLARE @mailman int
    -- Use "Chilkat_9_5_0.MailMan" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.MailMan', @mailman OUT

    -- Set the SMTP server and any required settings.
    EXEC sp_OASetProperty @mailman, 'SmtpHost', 'smtp.mymailserver.com'
    EXEC sp_OASetProperty @mailman, 'SmtpUsername', 'myLogin'
    EXEC sp_OASetProperty @mailman, 'SmtpPassword', 'myPassword'
    EXEC sp_OASetProperty @mailman, 'StartTLS', 1

    -- Create a new email object
    DECLARE @email int
    -- Use "Chilkat_9_5_0.Email" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Email', @email OUT

    EXEC sp_OASetProperty @email, 'Subject', 'This is a test'
    EXEC sp_OASetProperty @email, 'Body', 'This is a test'
    EXEC sp_OASetProperty @email, 'From', 'Chilkat Support <support@chilkatsoft.com>'
    EXEC sp_OAMethod @email, 'AddTo', @success OUT, 'Chilkat Admin', 'admin@chilkatsoft.com'

    -- Call the async version of the SendEmail method to return a task object.
    -- The task object is loaded, but is in the Inert state -- meaning it is
    -- not yet scheduled to run on Chilkat's background thread pool.
    DECLARE @task int
    EXEC sp_OAMethod @mailman, 'SendEmailAsync', @task OUT, @email
    EXEC sp_OAGetProperty @mailman, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @mailman, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @chilkatGlob
        EXEC @hr = sp_OADestroy @mailman
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    -- Schedule the task for running on the thread pool.  This changes the task's state
    -- from Inert to Live.
    EXEC sp_OAMethod @task, 'Run', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @task, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @task

        EXEC @hr = sp_OADestroy @chilkatGlob
        EXEC @hr = sp_OADestroy @mailman
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    -- The application is now free to do anything else
    -- while the email is being sent.

    -- For this example, we'll simply sleep and periodically
    -- check to see if the SendEmail if finished.  While checking
    -- however, we'll report on the progress.
    DECLARE @curPctDone int
    SELECT @curPctDone = 0
    EXEC sp_OAGetProperty @task, 'Finished', @iTmp0 OUT
    WHILE @iTmp0 <> 1
      BEGIN

        EXEC sp_OAGetProperty @task, 'PercentDone', @iTmp0 OUT
        IF @iTmp0 <> @curPctDone
          BEGIN
            EXEC sp_OAGetProperty @task, 'PercentDone', @curPctDone OUT

            PRINT @curPctDone + ' percent done'
          END

        -- Sleep 100 ms.
        EXEC sp_OAMethod @task, 'SleepMs', NULL, 100

      END

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

    -- If the task was "canceled", it was canceled prior to actually starting.  This could
    -- happen if the task was canceled while waiting in a thread pool queue to be scheduled by Chilkat's
    -- background thread pool scheduler.  

    -- If the task was "aborted", it indicates that it was canceled while running in a background thread.  
    -- The ResultErrorText will likely indicate that the task was aborted.

    -- If the task "completed", then it ran to completion, but the actual success/failure of the method
    -- is determined by the result obtained via a GetResult* method.  (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:
    EXEC sp_OAGetProperty @task, 'StatusInt', @iTmp0 OUT
    IF @iTmp0 <> 7
      BEGIN

        PRINT 'Task did not complete.'

        EXEC sp_OAGetProperty @task, 'Status', @sTmp0 OUT
        PRINT 'task status: ' + @sTmp0
        EXEC @hr = sp_OADestroy @task

        EXEC @hr = sp_OADestroy @chilkatGlob
        EXEC @hr = sp_OADestroy @mailman
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    -- The SendEmail method returns a boolean.  Therefore, after the task is finished,
    -- we can get the boolean result by calling GetResultBool.  This is the return value had
    -- we called SendEmail synchronously.
    EXEC sp_OAMethod @task, 'GetResultBool', @success OUT
    IF @success <> 1
      BEGIN
        -- The task's ResultErrorText contains what would have been in the LastErrorText property had
        -- the SendEmail method been called synchronously.
        EXEC sp_OAGetProperty @task, 'ResultErrorText', @sTmp0 OUT
        PRINT @sTmp0
      END
    ELSE
      BEGIN

        PRINT 'Email sent asynchronously.'
      END

    EXEC @hr = sp_OADestroy @task

    EXEC sp_OAMethod @mailman, 'CloseSmtpConnection', @success OUT
    IF @success <> 1
      BEGIN

        PRINT 'Connection to SMTP server not closed cleanly.'

      END

    EXEC @hr = sp_OADestroy @chilkatGlob
    EXEC @hr = sp_OADestroy @mailman
    EXEC @hr = sp_OADestroy @email


END
GO