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Re: HTTP Partial Download Query

From: Scott Lawrence <lawrence@world.std.com>
Date: 08 Dec 2002 10:43:43 -0500
To: "Yogesh Bang" <Y.Bang@zensar.com>
Cc: <ietf-http-wg@w3.org>
Message-ID: <usmx8wm6o.fsf@world.std.com>

"Yogesh Bang" <Y.Bang@zensar.com> writes:

> 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?

The client (browser) may request a specified range of the object; if
it wants another range, it must make another request.  The request is
made using the Range request header (see section 14.35 of RFC 2616).

Note however, that since a server MAY ignore a Range request header
and return the entire resource, a client that has a limited capacity
cannot always rely on getting a subrange response.  The Content-Range
header is included in the response if it is a subrange.

There is a mechanism (the 'Accept-Ranges' response header) designed to
allow the server to declare whether or not it will support range
requests for a resource - I don't know how widely it is implemented.
If it is implemented by the server, then an OPTIONS or HEAD request to
the URL of interest would return an Accept-Ranges header, without
having to deal with the entire object.

-- 
  Scott Lawrence
Received on Sunday, 8 December 2002 10:43:48 GMT

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