Range requests

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Hi there,

    We are in the process of adding Range requests to Squid 1.2 and need
your feedback. Range requests are very helpful for interrupted downloads
and fetching small portions of huge files.

draft-ietf-http-v11-spec-rev-01.txt:

   "HTTP/1.1 allows a client to request that only part (a range of) the
    response entity be included within the response."

In terms of implementation, we have two basic options:

    i) Support Range responses (i.e., respond with partial content if
       client requested one). However, always request an entire document for
       _cachable_ misses. Thus, Squid caches the whole thingy and then
       sends a portion of it to the client if needed. This is simple
       because only complete documents are cached (as usual).

   ii) Full support for caching of partial documents. This is hard
       because, ideally, several partial cached responses should be merged
       together, but they might correspond to different versions of a
       document, etc, etc...

We failed to find a reasonable application where (ii) is essential in
terms of functionality and/or performance. If you have any examples please
share them with us. Otherwise we may implement (i). There will be an
option that, in case of a miss, turns off requesting (and then caching) an
entire document instead of forwarding a Range request.

Thank you,

Alex.

P.S. "Client requesting a small portion of a huge document" is _not_ a
good example. A huge document is, most likely, not cachable. Thus, we will
not request it and will forward a Range request instead.

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Received on Tue Jul 29 2003 - 13:15:45 MDT