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Re: [XHR] chunked

From: Wenbo Zhu <wenboz@google.com>
Date: Wed, 7 Dec 2011 17:04:58 -0800
Message-ID: <CAD3-0rMK+LJfFrMUkTD-LqkWqQrzL5C5Pq3r9s42v4grJDdmdw@mail.gmail.com>
To: Anne van Kesteren <annevk@opera.com>
Cc: WebApps WG <public-webapps@w3.org>
On Wed, Nov 30, 2011 at 7:28 AM, Anne van Kesteren <annevk@opera.com> wrote:

> A while ago sicking proposed adding chunked support to XMLHttpRequest:
> http://lists.w3.org/Archives/**Public/public-webapps/**
> 2011JulSep/0741.html<http://lists.w3.org/Archives/Public/public-webapps/2011JulSep/0741.html>
> https://bugzilla.mozilla.org/**show_bug.cgi?id=687087<https://bugzilla.mozilla.org/show_bug.cgi?id=687087>
> A use case I remember was downloading a large file of some kind that
> presumably can be incrementally rendered as otherwise responseType "blob"
> should be sufficient. More use cases appreciated. Would help with the
> design.
E.g. voice/image search, translation ... IMHO any single resource that
involves non-trivial processing to produce would fit the use case.

> As for the feature, basically have responseType "chunked-text" and
> "chunked-arraybuffer" values and reset rather than update the response
> entity body with each progress event. And make sure that a progress event
> is dispatched when the last fetch event is queued. And make sure that this
> is only available for asynchronous usage.
> Charles asked whether "chunked-text" was really needed (and whether we
> should have "chunked" which implies ArrayBuffer instead). Nobody got back
> to him on that. If it is needed, how does it work when you just have some
> of the bytes of a multi-byte character in a single chunk? Fails to decode
> as per the normal algorithm?
When text is consumed as chunked streams, my take is that the application
code has to deal with partial frames, and partial chars are just one
sub-problem. So, I wouldn't consider multi-byte characters a particular

> Also, this basically makes it possible to write EventSource on top of
> XMLHttpRequest. Is that acceptable? If it encourages more people to use a
> lower-level API, higher-level optimizations for mobile phones might become
> harder down the road.
At the same time, lower-level APIs that match the underlying wire-protocol
(i.e. HTTP) would be equally important for optimization purposes.


> --
> Anne van Kesteren
> http://annevankesteren.nl/
Received on Thursday, 8 December 2011 01:20:48 UTC

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