Lianja

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. Lianja

llSuccess = .F.

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

loTlsRead = createobject("CkSocket")

// We'll just use an HTTPS server for this example...
llBUseTls = .T.
lnMaxWaitMs = 5000
llSuccess = loTlsRead.Connect("www.chilkatsoft.com",443,llBUseTls,lnMaxWaitMs)
if (llSuccess = .F.) then
    ? loTlsRead.LastErrorText
    release loTlsRead
    return
endif

// 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.

loTlsWrite = createobject("CkSocket")
llSuccess = loTlsRead.DupSocket(loTlsWrite)
if (llSuccess = .F.) then
    ? loTlsRead.LastErrorText
    release loTlsRead
    release loTlsWrite
    return
endif

// 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.
loTask = loTlsRead.ReceiveUntilMatchAsync(Chr(13) + Chr(10) + Chr(13) + Chr(10))
loTask.Run()

// Now send the request.  This should not block because the read is happening on the tlsRead object.
lcHttpGetReq = "GET / HTTP/1.1" + Chr(13) + Chr(10) + "Host: www.chilkatsoft.com" + Chr(13) + Chr(10) + Chr(13) + Chr(10)
llSuccess = loTlsWrite.SendString(lcHttpGetReq)
// Assuming success for the example...

// Wait for the read task to finish.
// The .T./.F. returned by Wait applies to the Wait method call, not the task.
lnMaxWaitMs = 5000
llSuccess = loTask.Wait(lnMaxWaitMs)
if (not llSuccess or (loTask.StatusInt <> 7) or (loTask.TaskSuccess <> .T.)) then
    if (not llSuccess) then
        // The task.LastErrorText applies to the Wait method call.
        ? loTask.LastErrorText
    else
        // The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        ? loTask.Status
        ? loTask.ResultErrorText
    endif

    release loTask
    release loTlsRead
    release loTlsWrite
    return
endif

// Examine the received HTTP response header:
? "HTTP response header:"
? loTask.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

release loTask

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


release loTlsRead
release loTlsWrite