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Re: Base

From: Terry Allen <tallen@fsc.fujitsu.com>
Date: Tue, 21 Jan 1997 17:06:46 -0800 (PST)
Message-Id: <199701220106.RAA13321@ishtar.fsc.fujitsu.com>
To: dmh@hpsgml.fc.hp.com, w3c-sgml-wg@www10.w3.org
Dave Hollander writes:
| While structure and syntax of links is important, there are many other 
| link concepts that need attention.  Since base has come up again, I will 
| start a new thread with an old complaint. The current web definition for
| "BASE" is not sufficient. 
| There was a long thread in another list that identified that base is 
| either,but not both:
| 	1) the url fragment to be used to complete partial URLs
| 	2) the url of the entity
| The tread did not reach agreement that the current web spec was not
| clear enough. There was agreement that the entity address was secondary.

draft-fielding-url-syntax-03.txt says:

D. Embedding the Base URL in HTML documents

   It is useful to consider an example of how the base URL of a document
   can be embedded within the document's content.  In this appendix, we
   describe how documents written in the Hypertext Markup Language
   (HTML) [3] can include an embedded base URL.  This appendix does not
   form a part of the relative URL specification and should not be
   considered as anything more than a descriptive example.

   HTML defines a special element "BASE" which, when present in the
   "HEAD" portion of a document, signals that the parser should use the
   BASE element's "HREF" attribute as the base URL for resolving any
   relative URLs.  The "HREF" attribute must be an absolute URL.  Note
   that, in HTML, element and attribute names are case-insensitive.  For

      <!doctype html public "-//IETF//DTD HTML//EN">
      <TITLE>An example HTML document</TITLE>
      <BASE href="http://www.ics.uci.edu/Test/a/b/c">
      ... <A href="../x">a hypertext anchor</A> ...               

   A parser reading the example document should interpret the given
   relative URL "../x" as representing the absolute URL


   regardless of the context in which the example document was obtained.

I'd say that points to (1) above, though I'm not quite sure what (2)
means, and the example given is not entirely unambiguous (is "a"
a directory or a filename?  seems to be intended as a directory).
It *is* clear that if there is no BASE in the HTML document, the
URL employed to obtain the document can be used as (the starting
point for determining?) the base URL.  The definitive doc to date is
RFC 1808 (ftp://ds.internic.net/rfc/rfc1808.txt). 
| Areas of conflict:
|  - Should base value *always* be displayed as the address of the document
| 	in browsers, hotlists, and other processing applications?

conflict between what?  which document?  do you mean base value or
base value+relative URL as arrived at per RFC 1808?

|  - Should the base be used to identify an alias for the document?
| 	If not, how?

what is an "alias for the document"?  which document?

|  - Should the application of the base value to a partial URL always imply
| 	a new entity? 

I think the rather involved algorithm in RFC 1808 does not prohibit
relative URLs that in fact point to the document containing them, and
in fact I don't see how it can.  But perhaps I misunderstand
"imply a new entity."

| (there...not a single TEI/HyTime term used)

well, you did use "entity" instead of "resource" ...

| Should not this group also be interested creating an othogonal definition
| for these concepts? 

Certainly not.  At least not for these concepts under these names; that's
for the IETF to deal with.  We should certainly clarify for ourselves
whatever seems unclear, though.  I don't see that we can prohibit 
the use of the BASE mechanism, or relative URLs, so if we have unresolved
problems we should present them to the (newly formed) URL WG.

    Terry Allen    Fujitsu Software Corp.    tallen@fsc.fujitsu.com
"In going on with these experiments, how many pretty systems do we build,
 which we soon find outselves obliged to destroy?" - Benjamin Franklin
  A Davenport Group Sponsor:  http://www.ora.com/davenport/index.html
Received on Tuesday, 21 January 1997 20:07:26 UTC

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