ReceiveString Returns Only the Immediately Available Data

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Demonstrates that Socket.ReceiveString returns only the text immediately available and not the entire response. The example connects to chilkatsoft.com over TLS and requests big_helloWorld.txt, a large text file of roughly 74,000 lines. A single ReceiveString call returns just the first portion of the response, and the example reports how many characters were received compared with the total size given by the response Content-Length header.

use chilkat();

$success = 0;

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

#  Connect to chilkatsoft.com over TLS.
$bTls = 1;
$maxWaitMs = 5000;
$success = $socket->Connect("chilkatsoft.com",443,$bTls,$maxWaitMs);
if ($success == 0) {
    print $socket->lastErrorText() . "\r\n";
    exit;
}

$socket->put_StringCharset("utf-8");

#  Send an HTTP GET request for big_helloWorld.txt, a large text file of roughly 74,000 lines of
#  "Hello World!".  This uses a minimal HTTP request only to exercise ReceiveString against a public
#  server -- for real HTTP work, use the Chilkat Http, Rest, or HttpCurl classes instead.
$httpReq = "GET /big_helloWorld.txt HTTP/1.1\r\nHost: chilkatsoft.com\r\nConnection: close\r\n\r\n";
$success = $socket->SendString($httpReq);
if ($success == 0) {
    print $socket->lastErrorText() . "\r\n";
    exit;
}

#  Call ReceiveString a single time.  It returns only the text that is immediately available --
#  typically just the first network packet -- and does NOT wait for the entire response to arrive.
$responseText = $socket->receiveString();
if ($socket->get_LastMethodSuccess() == 0) {
    print $socket->lastErrorText() . "\r\n";
    exit;
}

#  Load the received text into a StringBuilder so its length can be measured and the Content-Length
#  header extracted.  The Content-Length header gives the total size, in bytes, of the response body.
$sb = chilkat::CkStringBuilder->new();
$sb->Append($responseText);
$contentLength = $sb->getBetween("Content-Length: ","\r\n");
if ($sb->get_LastMethodSuccess() == 0) {
    print $sb->lastErrorText() . "\r\n";
    exit;
}

#  Compare what this single ReceiveString returned against the full size of the expected response.
#  The received amount is only a small fraction of the total.
print "Characters received so far (headers + partial body): " . $sb->get_Length() . "\r\n";
print "Expected response body size (Content-Length): " . $contentLength . " bytes" . "\r\n";

#  A single ReceiveString call returns whatever is currently available, so it cannot indicate whether
#  the full response has arrived.  This makes it difficult to know when a response is complete: the
#  application must either know how many bytes to expect (for example from a Content-Length header or
#  an application-defined length prefix) and keep receiving until that many bytes are collected, or
#  keep receiving until the peer closes the connection.