(DataFlex) 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

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    Handle hoTlsRead
    Boolean iBUseTls
    Integer iMaxWaitMs
    Boolean iSuccess
    Variant vTlsWrite
    Handle hoTlsWrite
    Variant vTask
    Handle hoTask
    String sHttpGetReq
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

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

    Get Create (RefClass(cComChilkatSocket)) To hoTlsRead
    If (Not(IsComObjectCreated(hoTlsRead))) Begin
        Send CreateComObject of hoTlsRead
    End

    // We'll just use an HTTPS server for this example...
    Move True To iBUseTls
    Move 5000 To iMaxWaitMs
    Get ComConnect Of hoTlsRead "www.chilkatsoft.com" 443 iBUseTls iMaxWaitMs To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTlsRead To sTemp1
        Showln sTemp1
        Procedure_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.

    Get ComCloneSocket Of hoTlsRead To vTlsWrite
    If (IsComObject(vTlsWrite)) Begin
        Get Create (RefClass(cComChilkatSocket)) To hoTlsWrite
        Set pvComObject Of hoTlsWrite To vTlsWrite
    End

    // 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.
    Get ComReceiveUntilMatchAsync Of hoTlsRead (character(13)) + (character(10)) + (character(13)) + (character(10)) To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComRun Of hoTask To iSuccess

    // Now send the request.  This should not block because the read is happening on the tlsRead object.
    Move "GET / HTTP/1.1" + (character(13)) + (character(10)) + "Host: www.chilkatsoft.com" + (character(13)) + (character(10)) + (character(13)) + (character(10)) To sHttpGetReq
    Get ComSendString Of hoTlsWrite sHttpGetReq To iSuccess
    // Assuming success for the example...

    // Wait for the read task to finish.
    // The True/False returned by Wait applies to the Wait method call, not the task.
    Move 5000 To iMaxWaitMs
    Get ComWait Of hoTask iMaxWaitMs To iSuccess
    Get ComStatusInt Of hoTask To iTemp1
    Get ComTaskSuccess Of hoTask To bTemp1
    If (Not iSuccess Or (iTemp1 <> 7) Or (bTemp1 <> True)) Begin
        If (Not iSuccess) Begin
            // The task.LastErrorText applies to the Wait method call.
            Get ComLastErrorText Of hoTask To sTemp1
            Showln sTemp1
        End
        Else Begin
            // The ResultErrorText applies to the underlying task method call (i.e. the Connect)
            Get ComStatus Of hoTask To sTemp1
            Showln sTemp1
            Get ComResultErrorText Of hoTask To sTemp1
            Showln sTemp1
        End

        Send Destroy of hoTask
        Send Destroy of hoTlsWrite
        Procedure_Return
    End

    // Examine the received HTTP response header:
    Showln "HTTP response header:"
    Get ComGetResultString Of hoTask To sTemp1
    Showln sTemp1

    // 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

    Send Destroy of hoTask
    Send Destroy of hoTlsWrite

    // Forget about the remainder of the HTTP response... The example was only to demonstrate
    // simultaneous reading/writing..
    Move 20 To iMaxWaitMs
    Get ComClose Of hoTlsRead iMaxWaitMs To iSuccess


End_Procedure