(Xojo Plugin) 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 Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim tlsRead As New Chilkat.Socket

// We'll just use an HTTPS server for this example...
Dim bUseTls As Boolean
bUseTls = True
Dim maxWaitMs As Int32
maxWaitMs = 5000
Dim success As Boolean
success = tlsRead.Connect("www.chilkatsoft.com",443,bUseTls,maxWaitMs)
If (success <> True) Then
    System.DebugLog(tlsRead.LastErrorText)
    Return
End If

// 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.

Dim tlsWrite As Chilkat.Socket
tlsWrite = tlsRead.CloneSocket()

// 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.
Dim task As Chilkat.Task
task = tlsRead.ReceiveUntilMatchAsync(EndOfLine.Windows + EndOfLine.Windows)
success = task.Run()

// Now send the request.  This should not block because the read is happening on the tlsRead object.
Dim httpGetReq As String
httpGetReq = "GET / HTTP/1.1" + EndOfLine.Windows + "Host: www.chilkatsoft.com" + EndOfLine.Windows + EndOfLine.Windows
success = tlsWrite.SendString(httpGetReq)
// 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.
maxWaitMs = 5000
success = task.Wait(maxWaitMs)
If (Not success Or (task.StatusInt <> 7) Or (task.TaskSuccess <> True)) Then
    If (Not success) Then
        // The task.LastErrorText applies to the Wait method call.
        System.DebugLog(task.LastErrorText)
    Else
        // The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        System.DebugLog(task.Status)
        System.DebugLog(task.ResultErrorText)
    End If

    Return
End If

// Examine the received HTTP response header:
System.DebugLog("HTTP response header:")
System.DebugLog(task.GetResultString())

// 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

// Forget about the remainder of the HTTP response... The example was only to demonstrate
// simultaneous reading/writing..
maxWaitMs = 20
success = tlsRead.Close(maxWaitMs)