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.

require 'chilkat'

success = false

socket = Chilkat::CkSocket.new()

#  Connect to chilkatsoft.com over TLS.
bTls = true
maxWaitMs = 5000
success = socket.Connect("chilkatsoft.com",443,bTls,maxWaitMs)
if (success == false)
    print socket.lastErrorText() + "\n";
    exit
end

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 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"
success = socket.SendString(httpReq)
if (success == false)
    print socket.lastErrorText() + "\n";
    exit
end

#  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 = Chilkat::CkStringBuilder.new()
success = socket.ReceiveSb(sb)
if (success == false)
    print socket.lastErrorText() + "\n";
    exit
end

#  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")
if (sb.get_LastMethodSuccess() == false)
    print sb.lastErrorText() + "\n";
    exit
end

#  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.
print "Characters received so far (headers + partial body): " + sb.get_Length().to_s() + "\n";
print "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.