ReceiveSb Returns Only the Immediately Available Data

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Demonstrates that Socket.ReceiveSb returns only the data 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 ReceiveSb 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.

<?php

use Chilkat2\Socket;
use Chilkat2\StringBuilder;

$socket = new Socket();

// Connect to chilkatsoft.com over TLS.
$bTls = true;
$maxWaitMs = 5000;
try {
    $socket->Connect('chilkatsoft.com', 443, $bTls, $maxWaitMs);

    $socket->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 ReceiveSb 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";
    $socket->SendString($httpReq);

    // Call ReceiveSb a single time.  It returns only the bytes that are immediately available --
    // typically just the first network packet -- and does NOT wait for the entire response to arrive.
    $sb = new StringBuilder();
    $socket->ReceiveSb($sb);

    // The response begins with HTTP headers.  The Content-Length header gives the total size, in bytes,
    // of the response body.
    $contentLength = $sb->GetBetween('Content-Length: ', "\r\n");
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

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

// A single ReceiveSb 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.