DataFlex

Asynchronous Sockets - Reading/Writing Data

See more Socket/SSL/TLS Examples

Demonstrates the following using async methods:

Demonstrates receiving text on a socket connection up to and including when an expected CRLF arrives. The example sends an HTTP HEAD request to an HTTP server and then reads the response header using ReceiveToCRLF and ReceiveUntilMatch.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSocket
    Boolean iUseTls
    Integer iMaxWaitMillisec
    Variant vConnectTask
    Handle hoConnectTask
    Boolean iConnectSuccess
    Variant vSendTask
    Handle hoSendTask
    Boolean iSendSuccess
    Variant vReceiveTask
    Handle hoReceiveTask
    String sResponseStatusLine
    String sResponseHeaderLine
    String sRemainderOfHeader
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

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

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

    // Connect using TLS to www.chilkatsoft.com
    // We could also use a normal TCP connection also by specifying port 80 with useTls = False.
    Move True To iUseTls
    Move 20000 To iMaxWaitMillisec
    Get ComConnectAsync Of hoSocket "www.chilkatsoft.com" 443 iUseTls iMaxWaitMillisec To vConnectTask
    If (IsComObject(vConnectTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoConnectTask
        Set pvComObject Of hoConnectTask To vConnectTask
    End
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Schedule the task for running on the thread pool.  This changes the task's state
    // from Inert to Live.
    Get ComRun Of hoConnectTask To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoConnectTask To sTemp1
        Showln sTemp1
        Send Destroy of hoConnectTask
        Procedure_Return
    End

    // The application is now free to do anything else.
    // For programming languages where Chilkat supports events, a TaskCompleted
    // event will fire when the task is completed.

    // For this example, we'll simply sleep and periodically
    // check to see when the connection is ready.
    While ((ComFinished(hoConnectTask)) <> True)

        // Sleep 10 ms.
        Send ComSleepMs To hoConnectTask 10

    Loop

    // A finished task could be one that was canceled, aborted, or truly finished.  

    // If the task was "canceled", it was canceled prior to actually starting.  This could
    // happen if the task was canceled while waiting in a thread pool queue to be scheduled by Chilkat's
    // background thread pool scheduler.  

    // If the task was "aborted", it indicates that it was canceled while running in a background thread.  
    // The ResultErrorText will likely indicate that the task was aborted.

    // If the task "completed", then it ran to completion, but the actual success/failure of the method
    // is determined by the result obtained via a GetResult* method.  (A "completed" task will
    // have a StatusInt equal to 7.   If the task finished, but was not completed, then it must've
    // been aborted or canceled:
    Get ComStatusInt Of hoConnectTask To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoConnectTask To sTemp1
        Showln "task status: " sTemp1
        Send Destroy of hoConnectTask
        Procedure_Return
    End

    Get ComGetResultBool Of hoConnectTask To iConnectSuccess
    If (iConnectSuccess <> True) Begin
        Showln "Connect failed."
        Get ComResultErrorText Of hoConnectTask To sTemp1
        Showln sTemp1
        Send Destroy of hoConnectTask
        Procedure_Return
    End

    Send Destroy of hoConnectTask

    // Tell the socket object that all text is to be sent in the utf-8 encoding,
    // and the text received is assumed to be utf-8.
    Set ComStringCharset Of hoSocket To "utf-8"

    // Send an HTTP HEAD request:
    Get ComSendStringAsync Of hoSocket "HEAD / HTTP/1.1" + (character(13)) + (character(10)) + "Host: www.chilkatsoft.com" + (character(13)) + (character(10)) + (character(13)) + (character(10)) To vSendTask
    If (IsComObject(vSendTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoSendTask
        Set pvComObject Of hoSendTask To vSendTask
    End
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComRun Of hoSendTask To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSendTask To sTemp1
        Showln sTemp1
        Send Destroy of hoSendTask
        Procedure_Return
    End

    // The application is now free to do anything else.
    // For programming languages where Chilkat supports events, 
    // a TaskCompleted event will fire when the task is completed.
    // This example will simply wait until the task completes...
    While ((ComFinished(hoSendTask)) <> True)
        // Sleep 10 ms.
        Send ComSleepMs To hoSendTask 10
    Loop

    Get ComStatusInt Of hoSendTask To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoSendTask To sTemp1
        Showln "task status: " sTemp1
        Send Destroy of hoSendTask
        Procedure_Return
    End

    Get ComGetResultBool Of hoSendTask To iSendSuccess
    If (iSendSuccess <> True) Begin
        Showln "Send failed."
        Get ComResultErrorText Of hoSendTask To sTemp1
        Showln sTemp1
        Send Destroy of hoSendTask
        Procedure_Return
    End

    Send Destroy of hoSendTask

    // Wait a maximum of 4 seconds while no data is forthcoming:
    Set ComMaxReadIdleMs Of hoSocket To 4000

    // To explain MaxReadIdleMs further:  In Chilkat, a max "idle timeout" is the max time to wait
    // while no additional data arrives on the socket.  Imagine if 10MB of data will be received
    // where the 1st CRLF occurs at the very end.  As long as the data continues arriving and does not
    // halt for more than 4000ms, then the ReceiveToCRLF will continue receiving.  It is only after
    // the connection becomes idle for more than 4000ms that the app will giveup and fail the read.

    // Get the 1st response line, which should be "HTTP/1.1 200 OK"
    Get ComReceiveToCRLFAsync Of hoSocket To vReceiveTask
    If (IsComObject(vReceiveTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoReceiveTask
        Set pvComObject Of hoReceiveTask To vReceiveTask
    End
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComRun Of hoReceiveTask To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoReceiveTask To sTemp1
        Showln sTemp1
        Send Destroy of hoReceiveTask
        Procedure_Return
    End

    // The application is now free to do anything else.
    // For programming languages where Chilkat supports events, 
    // a TaskCompleted event will fire when the task is completed.
    // This example will simply wait until the task completes...
    While ((ComFinished(hoReceiveTask)) <> True)
        // Sleep 10 ms.
        Send ComSleepMs To hoReceiveTask 10
    Loop

    Get ComStatusInt Of hoReceiveTask To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoReceiveTask To sTemp1
        Showln "task status: " sTemp1
        Send Destroy of hoReceiveTask
        Procedure_Return
    End

    Get ComGetResultString Of hoReceiveTask To sResponseStatusLine

    Showln "StatusLine: " sResponseStatusLine
    Send Destroy of hoReceiveTask

    // Now get the 1st line of the response header:
    Get ComReceiveToCRLF Of hoSocket To sResponseHeaderLine
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "HeaderLine: " sResponseHeaderLine

    // Now read the remainder of the response header by reading until a double CRLF is seen:
    Get ComReceiveUntilMatchAsync Of hoSocket (character(13)) + (character(10)) + (character(13)) + (character(10)) To vReceiveTask
    If (IsComObject(vReceiveTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoReceiveTask
        Set pvComObject Of hoReceiveTask To vReceiveTask
    End
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComRun Of hoReceiveTask To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoReceiveTask To sTemp1
        Showln sTemp1
        Send Destroy of hoReceiveTask
        Procedure_Return
    End

    // The application is now free to do anything else.
    // For programming languages where Chilkat supports events, 
    // a TaskCompleted event will fire when the task is completed.
    // This example will simply wait until the task completes...
    While ((ComFinished(hoReceiveTask)) <> True)
        // Sleep 10 ms.
        Send ComSleepMs To hoReceiveTask 10
    Loop

    Get ComStatusInt Of hoReceiveTask To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoReceiveTask To sTemp1
        Showln "task status: " sTemp1
        Send Destroy of hoReceiveTask
        Procedure_Return
    End

    Get ComGetResultString Of hoReceiveTask To sRemainderOfHeader

    Showln "Remainder: " sRemainderOfHeader
    Send Destroy of hoReceiveTask

    // Close the connection with the server
    // Wait a max of 20 seconds (20000 millsec)
    Get ComClose Of hoSocket 20000 To iSuccess


End_Procedure