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Re: CBOR Tutorial

From: Brady Duga <duga@google.com>
Date: Thu, 1 Feb 2018 06:50:53 -0800
Message-ID: <CAH_p_eX1FSkF6=q08QEkdK-hEkU5F147s3URt1+8mnPHuCF7pw@mail.gmail.com>
To: Leonard Rosenthol <lrosenth@adobe.com>
Cc: Romain <rdeltour@gmail.com>, Laurent Le Meur <laurent.lemeur@edrlab.org>, Baldur Bjarnason <baldur@rebus.foundation>, Ivan Herman <ivan@w3.org>, "Schindler Wolfgang Dr." <w.schindler@pons.de>, "Davis, Greg" <greg.davis@pearson.com>, Ric Wright <rkwright@geofx.com>, W3C Publishing Working Group <public-publ-wg@w3.org>
Sorry, not an expert in CBOR, but it does seem like it allows random
access, it just doesn't supply an index. But a client that wanted random
access to the items in the package it could generate an index easily
enough, either as a one-time pass over the complete package or during
download. Granted, you may have to sequentially run through every byte in
the data to generate that index due to indefinite strings and arrays, so
might not be the fastest operation in the world, but again it is a
one-time, fairly easy parse.

On Thu, Feb 1, 2018 at 2:22 AM, Leonard Rosenthol <lrosenth@adobe.com>
wrote:

> So be careful to not confuse the data model (aka manifests, bundles etc.)
> and then encoding (CBOR in this case).
>
>
>
> CBOR, by itself, does not support random access.
>
>
>
> However, a data model (such as the WebPack work) that is then encoded into
> CBOR can provide support for random access (or at least a limited set of
> it, based on the model).
>
>
>
> So yes if we were to adopt WebPack, we would achieve a level of random
> access.  (NOTE: if we do “object” compression, we may have to do some work
> on the manifest).
>
>
>
> Leonard
>
>
>
> *From: *Romain <rdeltour@gmail.com>
> *Date: *Thursday, February 1, 2018 at 2:18 PM
> *To: *Leonard Rosenthol <lrosenth@adobe.com>
> *Cc: *Laurent Le Meur <laurent.lemeur@edrlab.org>, Baldur Bjarnason
> <baldur@rebus.foundation>, Ivan Herman <ivan@w3.org>, "Schindler Wolfgang
> Dr." <w.schindler@pons.de>, "Davis, Greg" <greg.davis@pearson.com>, Ric
> Wright <rkwright@geofx.com>, W3C Publishing Working Group <
> public-publ-wg@w3.org>
> *Subject: *Re: CBOR Tutorial
>
>
>
>
>
> On 31 Jan 2018, at 17:58, Leonard Rosenthol <lrosenth@adobe.com> wrote:
>
>
>
> CBOR is a great exchange format for “over the wire” data exchange.   It is
> not a good format for “off the web” exchange (IMO)
>
>
>
>
>
> Primarily because its optimized for streaming and not random access.
>
>
>
> Random access is always a better model for data processing but assumes
> that you have all the data already present (as would you “off the web”).
> However, when streaming across a network/the web, you don’t always have the
> option (yes, there is byte range requests but they aren’t supported in all
> modern network configs, eg. load balancers).
>
>
>
> My understanding is that random access depends on the actual data model
> being encoded in CBOR?
>
>
>
> If I understand correctly, in the bundling spec, the index can be parsed
> first, and gives you pointers to each individual request/response pair,
> which effectively enables random access.
>
> Random access is btw stated as an essential requirement for the packaging
> spec: https://tools.ietf.org/html/draft-yasskin-webpackage-
> use-cases-00#section-3.1.5
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-yasskin-webpackage-use-cases-00%23section-3.1.5&data=02%7C01%7Clrosenth%40adobe.com%7Cd327d8c0b59840ef04a908d56950983d%7C71f1da39c0a84d5a8d88a67b23c30bf4%7C0%7C0%7C636530717246387501&sdata=1NyJIIdxm%2FW0M8JbNVCixug9iLGWd7GgCT2G9LdOnuo%3D&reserved=0>
>
>
>
> Am I missing something?
>
>
>
> Romain.
>
Received on Thursday, 1 February 2018 14:51:32 UTC

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