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.

Local $bSuccess = False

$oSocket = ObjCreate("Chilkat.Socket")

;  Connect to chilkatsoft.com over TLS.
Local $bTls = True
Local $iMaxWaitMs = 5000
$bSuccess = $oSocket.Connect("chilkatsoft.com",443,$bTls,$iMaxWaitMs)
If ($bSuccess = False) Then
    ConsoleWrite($oSocket.LastErrorText & @CRLF)
    Exit
EndIf

$oSocket.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.
Local $sHttpReq = "GET /big_helloWorld.txt HTTP/1.1" & @CRLF & "Host: chilkatsoft.com" & @CRLF & "Connection: close" & @CRLF & @CRLF
$bSuccess = $oSocket.SendString($sHttpReq)
If ($bSuccess = False) Then
    ConsoleWrite($oSocket.LastErrorText & @CRLF)
    Exit
EndIf

;  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.
$oSb = ObjCreate("Chilkat.StringBuilder")
$bSuccess = $oSocket.ReceiveSb($oSb)
If ($bSuccess = False) Then
    ConsoleWrite($oSocket.LastErrorText & @CRLF)
    Exit
EndIf

;  The response begins with HTTP headers.  The Content-Length header gives the total size, in bytes,
;  of the response body.
Local $sContentLength = $oSb.GetBetween("Content-Length: ",@CRLF)
If ($oSb.LastMethodSuccess = False) Then
    ConsoleWrite($oSb.LastErrorText & @CRLF)
    Exit
EndIf

;  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.
ConsoleWrite("Characters received so far (headers + partial body): " & $oSb.Length & @CRLF)
ConsoleWrite("Expected response body size (Content-Length): " & $sContentLength & " bytes" & @CRLF)

;  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.