(SQL Server) Async Methods Returning an Object

Demonstrates how to call an asynchronous method that returns an object. This example reads email from a POP3 server using the Async versions of the Chilkat methods.

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
    DECLARE @iTmp1 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @sTmp1 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 POP3 server's hostname
    EXEC sp_OASetProperty @mailman, 'MailHost', 'pop.someMailServer.com'

    -- Set the POP3 login/password and any other requirements..
    EXEC sp_OASetProperty @mailman, 'PopUsername', 'myLogin'
    EXEC sp_OASetProperty @mailman, 'PopPassword', 'myPassword'
    EXEC sp_OASetProperty @mailman, 'PopSsl', 1
    EXEC sp_OASetProperty @mailman, 'MailPort', 995

    -- Connect to the POP3 server:
    DECLARE @task int
    EXEC sp_OAMethod @mailman, 'Pop3BeginSessionAsync', @task OUT
    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
        RETURN
      END
    -- Start the background task.
    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 @chilkatGlob
        EXEC @hr = sp_OADestroy @mailman
        RETURN
      END
    -- Wait for the POP3 connect task to finish.
    -- The 1/0 returned by Wait applies to the Wait method call, not the task.
    DECLARE @maxWaitMs int
    SELECT @maxWaitMs = 30000
    EXEC sp_OAMethod @task, 'Wait', @success OUT, @maxWaitMs
    EXEC sp_OAGetProperty @task, 'StatusInt', @iTmp0 OUT
    EXEC sp_OAGetProperty @task, 'TaskSuccess', @iTmp1 OUT
    IF Not @success or (@iTmp0 <> 7) or (@iTmp1 <> 1)
      BEGIN
        IF Not @success
          BEGIN
            -- The task.LastErrorText applies to the Wait method call.
            EXEC sp_OAGetProperty @task, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
          END
        ELSE
          BEGIN
            -- The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
            EXEC sp_OAGetProperty @task, 'Status', @sTmp0 OUT
            PRINT @sTmp0
            EXEC sp_OAGetProperty @task, 'ResultErrorText', @sTmp0 OUT
            PRINT @sTmp0
          END
        EXEC @hr = sp_OADestroy @task

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

    EXEC @hr = sp_OADestroy @task

    -- Get the number of messages in the mailbox.
    EXEC sp_OAMethod @mailman, 'GetMailboxCountAsync', @task OUT

    -- To keep the example short, we'll skip handling failures.
    -- The failures would be handled in the same way as shown above.

    EXEC sp_OAMethod @task, 'Run', @success OUT
    EXEC sp_OAMethod @task, 'Wait', @success OUT, @maxWaitMs
    DECLARE @numMessages int
    EXEC sp_OAMethod @task, 'GetResultInt', @numMessages OUT
    EXEC @hr = sp_OADestroy @task

    IF @numMessages = 0
      BEGIN
        EXEC @hr = sp_OADestroy @chilkatGlob
        EXEC @hr = sp_OADestroy @mailman
        RETURN
      END

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

    DECLARE @i int

    SELECT @i = 1
    WHILE @i <= @numMessages
      BEGIN

        EXEC sp_OAMethod @mailman, 'FetchByMsgnumAsync', @task OUT, @i
        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
        EXEC sp_OAMethod @task, 'Run', @success OUT
        EXEC sp_OAMethod @task, 'Wait', @success OUT, @maxWaitMs
        EXEC sp_OAGetProperty @task, 'StatusInt', @iTmp0 OUT
        EXEC sp_OAGetProperty @task, 'TaskSuccess', @iTmp1 OUT
        IF Not @success or (@iTmp0 <> 7) or (@iTmp1 <> 1)
          BEGIN
            IF Not @success
              BEGIN
                -- The task.LastErrorText applies to the Wait method call.
                EXEC sp_OAGetProperty @task, 'LastErrorText', @sTmp0 OUT
                PRINT @sTmp0
              END
            ELSE
              BEGIN
                -- The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
                EXEC sp_OAGetProperty @task, 'Status', @sTmp0 OUT
                PRINT @sTmp0
                EXEC sp_OAGetProperty @task, 'ResultErrorText', @sTmp0 OUT
                PRINT @sTmp0
              END
            EXEC @hr = sp_OADestroy @task

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

        -- Each Chilkat object that can be a return value of an asynchronous task will
        -- have a method named LoadTaskResult.  The object returned in the underlying
        -- asynchronous method call is retrieved by calling LoadTaskResult. 

        -- To say it another way: The application will provide a pre-existing object of
        -- the desired return type (in this case it is an email object).  This object is
        -- loaded by calling LoadTaskResult.  

        EXEC sp_OAMethod @email, 'LoadTaskResult', @success OUT, @task
        EXEC @hr = sp_OADestroy @task

        IF Not @success
          BEGIN
            EXEC sp_OAGetProperty @email, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @chilkatGlob
            EXEC @hr = sp_OADestroy @mailman
            EXEC @hr = sp_OADestroy @email
            RETURN
          END
        ELSE
          BEGIN
            EXEC sp_OAGetProperty @email, 'From', @sTmp0 OUT

            EXEC sp_OAGetProperty @email, 'Subject', @sTmp1 OUT

            PRINT @sTmp0 + ': ' + @sTmp1 + CHAR(10)
          END

        SELECT @i = @i + 1
      END

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


END
GO