Re: Simple explanation of difference between XLink and

Peter Murray-Rust (peter@ursus.demon.co.uk)
Tue, 07 Jul 1998 17:18:36


At 10:51 07/07/98 -0400, James H. Blackwell Jr. wrote:
>Hi all,
>
>Can anyone out there give me a simple explanation of the differences
>between XLink and XPointer ? Also, how do they relate to XML-LINK ?

XML-LINK (aka XLL) was a first draft which incorporated BOTH the XPointer
and XLink drafts. The terminology is still in flux (I believe, for example,
that 'xml:link' may not yet be stable). I suggest you use terms with care
and allow for other people's use of obsolescent terms.

>
>The only difference I've seen so far between the two (XLink and
>XPointer) is that XPointer seems to deal with intra-document links (like
><A NAME="#LINK"> in HTML) whereas XLink deals with inter-document (like
>HTML concept of hyperlinks).

No. XPointer is the addressing mechanism for *any* links using XLink. XLink
describes the abstract structure of the links. Thus an Extended link could
have locators which use any of the forms allowed by XPointer.
>
>Also, what exactly is meant by a multidirectional link.

Eliot Kimber wrote a very good article on XML-DEV about a year ago. You'll
find it under 'Kimber' or look in XML-Jewels (apologies for lack of recent
maintenance).

>
>Examples of these would be helpful. I've read all the W3C docs and
>several other XML publications and still cannot come up with some
>concrete examples/scenarios to describe these terms adequately.

I think XML-DEV has a real opportunity to help here. At the moment I think
we are all waiting till the paint is dry. I'm tentatively hacking XPointer
and some of XLink into JUMBO2 and I expect others are doing the same with
their tools.

Note that XLink is potentially far more powerful than simple HTML-like
links. We can describe many abstract data structures using it.

P.

Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS http://www.nottingham.ac.uk/vsms, Virtual Hyperglossary
http://www.venus.co.uk/vhg