(SQL Server) Understanding Async Function Return Values

See more Async Examples

Explains how to get the return value of the function called synchonously in the background thread.

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
    -- Some Chilkat functions can be called asynchronously.
    -- If a function "Func" can be called asynchronously, there will be a corresponding "FuncAsync" function that returns a Task object.
    -- 
    -- When Task.Run is called, the synchronous "Func" runs in a background thread.
    -- 

    -- For Chilkat methods that return a status (1/0), get returned value by calling GetResultBool.
    -- For example..

    DECLARE @sock int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Socket', @sock OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- --------------------------------------------------------------
    -- Synchronous call returning 1/0
    DECLARE @success int
    EXEC sp_OAMethod @sock, 'Connect', @success OUT, 'example.com', 443, 1, 5000

    -- --------------------------------------------------------------
    -- Asynchronous call
    DECLARE @task int
    EXEC sp_OAMethod @sock, 'ConnectAsync', @task OUT, 'example.com', 443, 1, 5000
    -- ...
    EXEC sp_OAMethod @task, 'Run', @success OUT
    -- ...
    -- ...
    -- Get the status (1/0) value returned by the synchronous method called in the background thread.
    EXEC sp_OAMethod @task, 'GetResultBool', @success OUT

    -- --------------------------------------------------------------
    -- Synchronous call returning an integer
    DECLARE @count int
    EXEC sp_OAMethod @sock, 'ReceiveCount', @count OUT

    -- --------------------------------------------------------------
    -- Asynchronous call
    EXEC sp_OAMethod @sock, 'ReceiveCountAsync', @task OUT
    -- ...
    EXEC sp_OAMethod @task, 'Run', @success OUT
    -- ...
    -- ...
    -- Get the integer value returned by the synchronous method called in the background thread.
    EXEC sp_OAMethod @task, 'GetResultInt', @count OUT

    -- --------------------------------------------------------------
    -- Synchronous call returning an string
    DECLARE @s nvarchar(4000)
    EXEC sp_OAMethod @sock, 'ReceiveString', @s OUT

    -- --------------------------------------------------------------
    -- Asynchronous call
    EXEC sp_OAMethod @sock, 'ReceiveStringAsync', @task OUT
    -- ...
    EXEC sp_OAMethod @task, 'Run', @success OUT
    -- ...
    -- ...
    -- Get the string value returned by the synchronous method called in the background thread.
    EXEC sp_OAMethod @task, 'GetResultString', @s OUT

    -- --------------------------------------------------------------
    -- Synchronous call returning an object
    DECLARE @connection int
    EXEC sp_OAMethod @sock, 'AcceptNextConnection', @connection OUT, 5000

    -- --------------------------------------------------------------
    -- Asynchronous call
    EXEC sp_OAMethod @sock, 'AcceptNextConnectionAsync', @task OUT
    -- ...
    EXEC sp_OAMethod @task, 'Run', @success OUT
    -- ...
    -- ...
    -- Get the object returned by the synchronous method called in the background thread.
    -- We do this a little differently.  We create an new object of the same type,
    -- and then load it with the returned object (assuming it was not null).
    DECLARE @acceptedConnection int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Socket', @acceptedConnection OUT

    EXEC sp_OAGetProperty @task, 'TaskSuccess', @iTmp0 OUT
    IF @iTmp0 = 1
      BEGIN
        EXEC sp_OAMethod @acceptedConnection, 'LoadTaskResult', @success OUT, @task
      END

    EXEC @hr = sp_OADestroy @sock
    EXEC @hr = sp_OADestroy @acceptedConnection


END
GO