(SQL Server) Bidirectional Sockets (TLS or non-TLS, simultaneous reading and writing a connection)

This example demonstrates how to simultaneously read/write on a single socket connection.

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

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

    -- We'll just use an HTTPS server for this example...
    DECLARE @bUseTls int
    SELECT @bUseTls = 1
    DECLARE @maxWaitMs int
    SELECT @maxWaitMs = 5000
    DECLARE @success int
    EXEC sp_OAMethod @tlsRead, 'Connect', @success OUT, 'www.chilkatsoft.com', 443, @bUseTls, @maxWaitMs
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tlsRead, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tlsRead
        RETURN
      END

    -- Chilkat classes are thread-safe.  This means that only one method call can be active
    -- at a time for a given object instance.  It would seem that this would prevent the possibility
    -- to simultaneously read/write a given connection because it would require two method calls
    -- to be simultaneously active: one for reading and one for writing.
    -- 
    -- There's a trick to doing it...
    -- 
    -- The CloneSocket method is provided to get a new object instance that shares the same socket
    -- connection.  This allows for the coarse-grained object-level thread safety to be maintained, 
    -- while finer-grained thread-safety mechanisms keep things kosher internally.

    -- One object will be used for reading, and the cloned socket is used for writing.
    -- It doesn't matter which --  you can use the cloned socket for reading or the original for writing.
    -- However.. if you try to read simultneously from both the original and cloned objects at the same
    -- time, then one will block until the other finishes.  (This is because of the finer-grained thread
    -- safety internally.)  The same is true if you try to write both socket objects simultaneously.

    DECLARE @tlsWrite int
    EXEC sp_OAMethod @tlsRead, 'CloneSocket', @tlsWrite OUT

    -- Let's start an async read on the socket.  Nothing will be arriving until we actually send the GET
    -- request and the server responds.  This will read until the end of the HTTP response header.
    DECLARE @task int
    EXEC sp_OAMethod @tlsRead, 'ReceiveUntilMatchAsync', @task OUT, CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10)
    EXEC sp_OAMethod @task, 'Run', @success OUT

    -- Now send the request.  This should not block because the read is happening on the tlsRead object.
    DECLARE @httpGetReq nvarchar(4000)
    SELECT @httpGetReq = 'GET / HTTP/1.1' + CHAR(13) + CHAR(10) + 'Host: www.chilkatsoft.com' + CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10)
    EXEC sp_OAMethod @tlsWrite, 'SendString', @success OUT, @httpGetReq
    -- Assuming success for the example...

    -- Wait for the read task to finish.
    -- The 1/0 returned by Wait applies to the Wait method call, not the task.
    SELECT @maxWaitMs = 5000
    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 Connect)
            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 @tlsWrite

        EXEC @hr = sp_OADestroy @tlsRead
        RETURN
      END

    -- Examine the received HTTP response header:

    PRINT 'HTTP response header:'
    EXEC sp_OAMethod @task, 'GetResultString', @sTmp0 OUT
    PRINT @sTmp0

    -- We should get a response that looks like this:
    -- 	HTTP response header:
    -- 	HTTP/1.1 200 OK
    -- 	Cache-Control: private
    -- 	Content-Length: 7477
    -- 	Content-Type: text/html
    -- 	Server: Microsoft-IIS/8.5
    -- 	Set-Cookie: ASPSESSIONIDSWDSTRTQ=BBNMIKGCHFJNILFFPLDIOGDE; secure; path=/
    -- 	X-Powered-By: ASP.NET
    -- 	X-Powered-By-Plesk: PleskWin
    -- 	Date: Thu, 06 Apr 2017 12:03:30 GMT

    EXEC @hr = sp_OADestroy @task

    EXEC @hr = sp_OADestroy @tlsWrite

    -- Forget about the remainder of the HTTP response... The example was only to demonstrate
    -- simultaneous reading/writing..
    SELECT @maxWaitMs = 20
    EXEC sp_OAMethod @tlsRead, 'Close', @success OUT, @maxWaitMs

    EXEC @hr = sp_OADestroy @tlsRead


END
GO