Re: I-D Submission: draft-lee-httpext-metadata-00.txt

As I have stated many times over the past few years, there isn’t a perfect
solution for this. The trick is to find the most suitable tradeoff.

Some of the problems with your proposal include:

1. This does not work well with caching since the response is different
based on the presence of this new header field. This means that every cache
in the world will need to change to differentiate between the three request
modes you introduced. This will never happen.

2. Metadata is often big and not suitable for inclusion in headers.

3. By putting the metadata in a header, you are breaking one of the core
principals of the web - the ability to reference objects using links.
Metadata is also data, and should have its own URI. In addition, the
metadata can also have metadata but your proposal does not accommodate this
use case (which is pretty common when it comes to using protocols such as
OAuth).

4. Since the header isn't a separate entity (i.e. #3), it is bound to the
security consideration of the resource itself. This is too limited as in
many cases, the permissions of the resource are different from the
permissions of the metadata.

5. The proposal doesn't address authoring and manipulating the metadata. By
putting data in a header field, you lose everything HTTP has to offer. You
can't POST/DELETE/PUT metadata. In fact, the only way to manipulate metadata
in your proposal is to have admin access to the web server.

6. This is too hard to deploy. Most web servers are not setup to manipulate
headers in this way. A proposal like this will require native support which
is never going to happen.

This is a partial list. Using the link header adds one layer of indirection
but is much more inline with web architecture and existing tools.

EHL


On 7/3/10 10:28 PM, "이문상" <sang0627.lee@samsung.com> wrote:

> 
> 
> Thanks for your comments, Eran.
> According to your suggestion, I've read documents you mentioned. And, let
> me ask and explain several things which show differences between my
> proposal and other prior proposals.
> 
> If a context IRI is "http://domain/music.mp3", how does the Link header
> provide additional information about music.mp3? It may provide Link header
> like Link: <music.xml>; rel="describedby" type="application/powder+xml"
> while combining Link header and POWDER. Or, It may also possible to combine
> Link header and hostmeta as you mentioned. However, if we focus on the
> acquisition of resource meta-data, these kinds of approach enlarge response
> time and complicate server maintenance as below.
> 
> 1. Indirect meta-data
> Any combination using existing standards requires two separate requests to
> get the meta-data of a resource, one for retrieving Link header and the
> other for retrieving meta-data itself. It increases response time for meta-
> data acquisition transaction and overall network traffic.
> 
> 2. Consistency consideration
> According to previous proposals, it is required to keep consistency between
> a resource and its meta-data. For example, if a publisher has modified or
> removed music.mp3, then its linked document should also be modified or
> removed to keep the consistency. Web is alive and millions of resources are
> created, modified, and removed every day. Updating resource status to its
> linked document is not trivial especially for large web server with dynamic
> contents.
> 
> 
> Regards,
> Moon-Sang Lee
> 
> ---
> Moon-Sang Lee, Senior Engineer, Ph.D.
> Convergence Software Lab., Digital Media & Communication R&D Center,
> Samsung Electronics Co., Ltd.,
> TEL: +82-31-279-8082
> Email: sang0627.lee@samsung.com
> Wisdom begins in wonder. *Socrates*
> 
> 
> -----Original Message-----
> From: Eran Hammer-Lahav [mailto:eran@hueniverse.com]
> Sent: Saturday, June 26, 2010 4:54 PM
> To: 이문상; ietf-http-wg@w3.org
> Subject: RE: I-D Submission: draft-lee-httpext-metadata-00.txt
> 
> Hi,
> 
> You are entering an area with a lot of prior experience.
> 
> There is little reason to extend HTTP with additional headers given the
> recent work on the HTTP Link header [1] (and the 'describedby' relation
> type), as well as the POWDER [2] and XRD [3] descriptor formats, and the
> host-meta proposal [4] which is currently in last call. In addition, you
> might want to take a look at analysis included in an early draft of LRDD
> [5] which covers existing methods for obtaining resource metadata.
> 
> Between using the HTTP Link header and host-meta, you should have full
> coverage of what you are trying to do, without having to create any new
> mechanism.
> 
> EHL
> 
> [1] http://tools.ietf.org/html/draft-nottingham-http-link-header

> [2] http://www.w3.org/TR/powder-dr/

> [3] http://www.oasis-open.org/apps/org/workgroup/xri/download.php/38236/xrd-

> 1.0-wd17.html
> [4] http://tools.ietf.org/html/draft-hammer-hostmeta

> [5] http://tools.ietf.org/html/draft-hammer-discovery-03#appendix-B

> 
> 
> 
>> -----Original Message-----
>> From: ietf-http-wg-request@w3.org [mailto:ietf-http-wg-request@w3.org]
>> On Behalf Of ???
>> Sent: Friday, June 25, 2010 7:48 PM
>> To: ietf-http-wg@w3.org
>> Subject: FW: I-D Submission: draft-lee-httpext-metadata-00.txt
>> 
>> 
>> FYI.
>> 
>> ---
>> Moon-Sang Lee, Senior Engineer, Ph.D.
>> Convergence Software Lab., Digital Media & Communication R&D Center,
>> Samsung Electronics Co., Ltd.,
>> TEL: +82-31-279-8082
>> Email: sang0627.lee@samsung.com
>> Wisdom begins in wonder. *Socrates*
>> 
>> -----Original Message-----
>> From: IETF I-D Submission Tool [mailto:idsubmission@ietf.org]
>> Sent: Friday, June 25, 2010 4:34 PM
>> To: internet-drafts@ietf.org
>> Cc: sang0627.lee@samsung.com; sang0627.lee@samsung.com
>> Subject:
>> 
>> Message-Id: <20100625073403.CBA163A69A1@core3.amsl.com>
>> Date: Fri, 25 Jun 2010 00:33:55 -0700 (PDT)
>> 
>> ,junglok.yu@samsung.com
>> Subject: Manual Post Requested for draft-lee-httpext-metadata
>> Content-Type: text/plain; charset="utf-8"
>> Mime-Version: 1.0
>> 
>> Manual Posting Requested for following Internet-Draft:
>> 
>> I-D Submission Tool URL:
>> https://datatracker.ietf.org/idst/status.cgi?submission_id=24392

>> 
>> 
>> Filename:        draft-lee-httpext-metadata
>> Version:         00
>> Staging URL:     http://www.ietf.org/staging/draft-lee-httpext-metadata-

>> 00.txt
>> Title:                   A New Header For Metadata Exchange
>> Creation_date:           2010-06-25
>> WG ID:                   Individual Submission
>> Number_of_pages: 11
>> Abstract:
>> This document provides a mechanism by which web servers can provide
>> metadata of a web resource which is indicated by a URL.  The web
>> client like web browser can use this metadata to filter out unwanted
>> web resource or link to itself.  In addition, the web client can take
>> advantage of such metadata to provide high-level services like
>> displaying additional information about the web resource without
>> downloading it.  We expect this mechanism to enable quick access to
>> metadata of any web resource from any web client reduces overall web
> traffic remarkably.
>> 
>> Submitter: Moon-Sang Lee (sang0627.lee@samsung.com)
>> 
>> Author(s):
>> Moon-Sang Lee, sang0627.lee@samsung.com
>> 
>> Jung-Lok Yu, junglok.yu@samsung.com
>> 
>> 
>> Comment:
>> Thank you!
>> 
> 
> 
>

Received on Sunday, 4 July 2010 15:20:34 UTC