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Re: Last call comments on XML Base

From: Paul Grosso <pgrosso@arbortext.com>
Date: Wed, 28 Jun 2000 15:16:27 -0500
Message-Id: <3.0.32.20000628151618.00f21224@pophost.arbortext.com>
To: "Martin J. Duerst" <duerst@w3.org>, www-xml-linking-comments@w3.org
Martin,

I'd like to discuss this, but I'm not sure www-xml-linking-comments@w3.org
is the right place.  (1) Are you subscribed to w3c-xml-linking-ig@w3.org
and (2) do I have your permission to copy your comments below there and
reply to them?

paul

At 21:53 2000 06 28 +0900, Martin J. Duerst wrote:
>2) This relates to
>    http://www.w3.org/2000/06/xmlbase-comments-20000607#IDw_Aq1.
>    I'm clearly not satisfied with:
>    - The resolution of the WG
>    - The arguments given in the disposition of comments
>    - The implementation of the resolution of the WG in the
>      current draft.
>    I think the question at hand is very important for the
>    overall XML architecture, and should be discussed more
>    carefully.
>
>    Here some details:
>    As for the implementation of the resolution of the WG
>    in the current draft, the WG decided to do
>    "Note the discrepancy and warn users about it."
>
>    What I would have expected was at least a note like:
>    "Note that the fact that xml:base does not extend into
>     external entities means that:
>     - Replacing entity references by their replacement text
>       can change the meaning of a document.
>     - To avoid this, make sure that all relative URI in an
>       external entity are governed by an absolute xml:base
>       in that enity."
>
>    I did not find any such note. The note about attribute
>    values provided via entities or defaults is discussing
>    another issue.
>
>    The arguments given in the disposition of comments are
>    as follows:
>
>    1. Canonicalization already breaks things, so the existence
>       of scenarios broken solely by this feature is dubious.
>
>    This argument is obviously bogus. Currently, the only
>    use of Canonicalization is signing, which is no reason
>    to break all the rest. Also, I don't really know where
>    'Canonicalization breaks things'. Canonicalization
>    over entities and then entity replacement is not the
>    same as overall Canonicalization, but Canonicalization
>    was not designed for external entities, and Canonicalization
>    over the whole document resolves entities. On the other
>    hand, I don't see how Canonicalization breaks xml:base
>    except for exactly the issue at hand.
>
>    2. The base would be context dependent when relative URIs are
>       used, which would tend to be confusing and
>       may cause unexpected behavior, e.g. broken links.
>
>    Yes, some behaviours may be unexpected. Resolving entities
>    may also lead to unexpected behaviours and break links.
>    The question are:
>    - How to define things so that the amount of dependencies
>      in the overall architecture is minimized.
>    - How to define things so that there is a way to get
>      various desired behaviors. It is always possible to
>      put an xml:base into an external entity (or to put it
>      just around the entity refernce if the entity itself
>      cannot be changed) if xml:base extends into external
>      entities, but it is completely impossible to get the
>      inverse behaviour if xml:base doesn't extend into
>      external entities.
>
>    3. See the concerns about the wisdom of this practice raised
>       by the comment "XBase is in conflict with RFC 2396".
>
>    I do not see any such concerns in these comments. That comment
>    is about xml:base extending from external entities. That comment
>    provides at least two good arguments for making xml:base extend
>    into external entities:
>    - It is the default behavior in inclusion cases defined in RFC 2396
>      (5.1.2. Base URI from the Encapsulating Entity)
>      (RFC 2396 allows to overwrite that default, but that does
>       not at all mean that RFC 2396 provides a reason for it).
>    - Making xml:base extend from external entities but not into
>      external entities seems is inconsistent.
>
>    4. Suggested behavior is inconsistent with the Infoset and
>       the XPath Data Model.
>
>    I'm highly confused here. XPath assumes that all entities
>    are resolved, has therefore no way to know entity boundaries,
>    and has therefore no way to make sure that xml:base extends
>    into internal entities, but not into external entities.
>
>    [On rereading some things, I have a hutch that we might
>     all want the same thing, but didn't understand each other.
>     If that's the case, then at least I consider the phrase
>     'does not extend into external entities' extremely
>     misleading. Anyway, this needs very careful check either way.]
Received on Wednesday, 28 June 2000 16:16:32 GMT

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