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Re: HTTP Partial Download Query

From: Patrick R. McManus <mcmanus@ducksong.com>
Date: Sun, 8 Dec 2002 10:14:49 -0500
To: Yogesh Bang <Y.Bang@zensar.com>
Cc: ietf-http-wg@w3.org
Message-ID: <20021208151449.GA32448@ducksong.com>

[Yogesh Bang: Dec 08 18:48]

> I was browsing through RFC 2616 for HTTP1.1
> One of the smart feature it mensioned was of PARTIAL DOWNLOAD.
> Means browser can specify a range of bytes (e.g 100-200 bytes of img123.gif)
> in the HTTP header and webserver will send only those bytes.
> 
> I have following query about PARTIAL DOWNLOAD
> 
> If the browser is capable of accepting say 100KB at a time (This 
> is most likely scenario in case of browsers on Mobile phones)
> then is it browser's responsibility to make request for every 100KB 
> of that object(which is to be downloaded) and the webserver will send requested 
> bytes? 
> OR
> Is it the server who will send the requested Object in chunk of 100KB
> with seperator and as Multipart response?

your first scenario is much closer.. the server will send only a
subset of the document.. if the client wants other subsets it must
make multiple requests. Also note that the server is allowed to just
send you the whole document even if you only ask for part of it.

imho, your issue appears to be one of flow control, which isn't really
what the range mechanism was meant for. (but then I'm not one to talk,
I've done an experiment to try and interleave different documents from
the same web page across the same persistent tcp stream using range).You should
really use your transport protocol to accomplish what you're
after. (e.g. in TCP advertise a 0 rwin and you won't get any more data
until you've consumed the last chunk.)

-Patrick
Received on Sunday, 8 December 2002 10:07:47 GMT

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