VB.NET Requires Chilkat v11.0.0+

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

See more Socket/SSL/TLS Examples

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

Dim success As Boolean = False

'  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 = True
Dim maxWaitMs As Integer = 5000
success = tlsRead.Connect("www.chilkatsoft.com",443,bUseTls,maxWaitMs)
If (success = False) Then
    Debug.WriteLine(tlsRead.LastErrorText)
    Exit Sub
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 DupSocket 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 New Chilkat.Socket
success = tlsRead.DupSocket(tlsWrite)
If (success = False) Then
    Debug.WriteLine(tlsRead.LastErrorText)
    Exit Sub
End If


'  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 = tlsRead.ReceiveUntilMatchAsync(vbCrLf & vbCrLf)
task.Run()

'  Now send the request.  This should not block because the read is happening on the tlsRead object.
Dim httpGetReq As String = "GET / HTTP/1.1" & vbCrLf & "Host: www.chilkatsoft.com" & vbCrLf & vbCrLf
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.
        Debug.WriteLine(task.LastErrorText)
    Else
        '  The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        Debug.WriteLine(task.Status)
        Debug.WriteLine(task.ResultErrorText)
    End If


    Exit Sub
End If


'  Examine the received HTTP response header:
Debug.WriteLine("HTTP response header:")
Debug.WriteLine(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
tlsRead.Close(maxWaitMs)