(Objective-C) 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.

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#import <CkoSocket.h>
#import <CkoTask.h>
#import <NSString.h>

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

CkoSocket *tlsRead = [[CkoSocket alloc] init];

// We'll just use an HTTPS server for this example...
BOOL bUseTls = YES;
int maxWaitMs = 5000;
BOOL success = [tlsRead Connect: @"www.chilkatsoft.com" port: [NSNumber numberWithInt: 443] ssl: bUseTls maxWaitMs: [NSNumber numberWithInt: maxWaitMs]];
if (success != YES) {
    NSLog(@"%@",tlsRead.LastErrorText);
    return;
}

// 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.

CkoSocket *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.
CkoTask *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.
NSString *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 YES/NO returned by Wait applies to the Wait method call, not the task.
maxWaitMs = 5000;
success = [task Wait: [NSNumber numberWithInt: maxWaitMs]];
if (!success || ([task.StatusInt intValue] != 7) || (task.TaskSuccess != YES)) {
    if (!success) {
        // The task.LastErrorText applies to the Wait method call.
        NSLog(@"%@",task.LastErrorText);
    }
    else {
        // The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        NSLog(@"%@",task.Status);
        NSLog(@"%@",task.ResultErrorText);
    }

    return;
}

// Examine the received HTTP response header:
NSLog(@"%@",@"HTTP response header:");
NSLog(@"%@",[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: [NSNumber numberWithInt: maxWaitMs]];