(Perl) 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 Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

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

$tlsRead = chilkat::CkSocket->new();

# We'll just use an HTTPS server for this example...
$bUseTls = 1;
$maxWaitMs = 5000;
$success = $tlsRead->Connect("www.chilkatsoft.com",443,$bUseTls,$maxWaitMs);
if ($success != 1) {
    print $tlsRead->lastErrorText() . "\r\n";
    exit;
}

# 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.

# tlsWrite is a 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.
# task is a Task
$task = $tlsRead->ReceiveUntilMatchAsync("\r\n\r\n");
$task->Run();

# Now send the request.  This should not block because the read is happening on the tlsRead object.
$httpGetReq = "GET / HTTP/1.1\r\nHost: www.chilkatsoft.com\r\n\r\n";
$success = $tlsWrite->SendString($httpGetReq);
# Assuming success for the example...

# Wait for the read task to finish.
# The 1/0 returned by Wait applies to the Wait method call, not the task.
$maxWaitMs = 5000;
$success = $task->Wait($maxWaitMs);
if (!$success or ($task->get_StatusInt() != 7) or ($task->get_TaskSuccess() != 1)) {
    if (!$success) {
        # The task.LastErrorText applies to the Wait method call.
        print $task->lastErrorText() . "\r\n";
    }
    else {
        # The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        print $task->status() . "\r\n";
        print $task->resultErrorText() . "\r\n";
    }

    exit;
}

# Examine the received HTTP response header:
print "HTTP response header:" . "\r\n";
print $task->getResultString() . "\r\n";

# 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);