SQL Server

Using IMAP IDLE to Wait for Updates

This example demonstrates how to use the IMAP IDLE functionality in Chilkat. SQL Server

-- 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)
    DECLARE @success int
    SELECT @success = 0

    DECLARE @imap int
    EXEC @hr = sp_OACreate 'Chilkat.Imap', @imap OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- ....
    -- ....
    -- ....

    -- Select an IMAP mailbox
    EXEC sp_OAMethod @imap, 'SelectMailbox', @success OUT, 'INBOX'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @imap, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @imap
        RETURN
      END

    -- After a mailbox has been selected, IDLE may begin.
    -- Idling tells the IMAP server to push unsolicited updates for the selected
    -- mailbox to the connected client (which is your application).
    EXEC sp_OAMethod @imap, 'IdleStart', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @imap, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @imap
        RETURN
      END

    -- Once idling has started, your code still has to periodically check to see
    -- if any updates have arrived.  However, this is significantly different
    -- then what normally occurs when checking email.  The IdleCheck does NOT
    -- send a message to the IMAP server.  It simply checks the connection to see
    -- if any data has arrived.  If so, it can be consumed and the client (your app)
    -- can react appropriately.  

    -- Note: It is recommended that idling only run for a max of 20 minutes before stopping and
    -- re-starting the IDLE.  This is to maintain a minimum low level of activity so that 
    -- the IMAP server does not disconnect (which it may do if it considers the connection to 
    -- be truly inactive, i.e. forgotten).

    -- To check the connection for IDLE updates, call IdleCheck.  The 1st argument indicates how
    -- long we're willing to wait. We'll wait 1 millisecond:
    DECLARE @idleResultXml nvarchar(4000)

    EXEC sp_OAMethod @imap, 'IdleCheck', @idleResultXml OUT, 1
    EXEC sp_OAGetProperty @imap, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @imap, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @imap
        RETURN
      END

    -- See the online reference documentation for details regarding the XML that is returned.
    -- Your application code would parse the XML to determine what action to take.
    -- If the XML contains "<idle></idle>", then no updates are available and your application
    -- would call IdleCheck again at some point in the future.

    -- If updates are available, the IDLE must be terminated by calling IdleDone, like this:
    EXEC sp_OAMethod @imap, 'IdleDone', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @imap, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @imap
        RETURN
      END

    -- Once the IDLE is terminated, your application can make calls to fetch email, etc.
    -- Any attempt to communicate with the IMAP server prior to terminating the IDLE will
    -- result in failure.

    -- IMPORTANT: Please realize that your application code will be structured differently than shown here.
    -- The call to IdleCheck will likely be in a function/procedure that is periodically called
    -- after the IdleStart has been called from some other location in your app

    EXEC @hr = sp_OADestroy @imap


END
GO