(SQL Server) Async Methods Returning an String

Demonstrates how to call an asynchronous method that returns a string. This example sends an HTTPS GET request to a URL and gets the HTML response.

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)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @http int
    -- Use "Chilkat_9_5_0.Http" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Http', @http OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @task int
    EXEC sp_OAMethod @http, 'QuickGetStrAsync', @task OUT, 'https://www.chilkatsoft.com/helloWorld.html'
    EXEC sp_OAGetProperty @http, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @http, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        RETURN
      END
    -- Start the background task.
    DECLARE @success int
    EXEC sp_OAMethod @task, 'Run', @success OUT
    IF Not @success
      BEGIN
        EXEC sp_OAGetProperty @task, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @task

        EXEC @hr = sp_OADestroy @http
        RETURN
      END

    -- The application is now free to do anything else

    -- For this example, we'll simply sleep and periodically
    -- check to see if the HTTPS GET if finished.
    EXEC sp_OAGetProperty @task, 'Finished', @iTmp0 OUT
    WHILE @iTmp0 <> 1
      BEGIN
        -- 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 @http
        RETURN
      END

    -- The QuickGetStr method returns a string.  Therefore, after the task is finished,
    -- we can get the string result by calling GetResultString.  This is the return value had
    -- we called QuickGetStr synchronously.
    DECLARE @html nvarchar(4000)
    EXEC sp_OAMethod @task, 'GetResultString', @html OUT


    PRINT @html

    EXEC @hr = sp_OADestroy @task


    EXEC @hr = sp_OADestroy @http


END
GO