RE: [docbook] XLink and OLink in Docbook 5

["Peter Ring" <PRI at magnus dot dk>]

I'm really busy looking into requirements right now.

We like the indirections that olink provides. URI references (as names) can be used to identify external documents, but I strongly suspect that URLs (as resolvable identifiers) won't work. We're talking about heavy re-use of documents that are published in print as well as online in contexts that are unknown at document authoring time.

That's why extended links, stored in a linkbase, would be nice. Documents are not edited simultaneously, have a much slower lifecycle than links, and we'd rather not touch source documents whenever authors and editors feel like adding a link.

We might want to use the full XPointer xpointer() scheme in locators in order to link to or from ranges. Except I'm not sure we'll be able to find an XLink processor that supports it... But really, we are not much worse off than wrt XSL-FO.

Here's a number of implementations:

Fujitsu is maintaining XLiP for use in XBRL work.
http://software.fujitsu.com/en/interstage-xwand/activity/xbrltools/xlip/

XTooX has disappeared, and might have been folded into xlinkit
http://www.systemwire.com/

X-Hive/DB includes an XLink engine
http://www.x-hive.com/products/db/index.html

4Suite implements some level of XLink support
http://www.4suite.org/index.xhtml

STEP UK's X2X has disappeared, and might have been folded into empolis Publication Build Service
http://www.empolis.com/en/D29DBAB9363E4D3480010261D1371BAF_3D858E3FC5AE42909DF18B8A5E99C2CB.php

Kind regards
Peter Ring

> -----Original Message-----
> From: Jirka Kosek [mailto:jirka@kosek.cz]
> Sent: 16. februar 2005 16:29
> To: Peter Ring
> Cc: docbook@lists.oasis-open.org
> Subject: Re: [docbook] XLink and OLink in Docbook 5
> 
> 
> Peter Ring wrote:
> 
> > We're considering up-translating some legacy content with lots of
> > external links and cross-references to Docbook. We've been using
> > olink for maintaining external links, so I'd like to get an idea
> > about what to expect from Docbook V5.0. Can I re-implement the
> > existing targetdoc#targetptr semantics of olink with xlink?
> 
> Yes, you can. There is an easy mapping from DocBook 4.x linking into 
> DocBook 5 linking:
> 
> 1) link, xref
> 
> <link linend="foo">...</link> (same for xref)
> 
> can be written as:
> 
> <link linend="foo">...</link>
> or
> <link xlink:href="#foo">...</link>
> 
> 2) ulink
> 
> <ulink url="foo">...</link>
> 
> will be
> 
> <link xlink:href="foo">...</link>
> 
> 3) olink
> 
> This mapping is not so straightforward as targetdoc in olink 
> is not URI 
> but rather identifier pointing into olink database. So one 
> possibility 
> is to use real URI of referenced document instead of symbolic name:
> 
> <link xlink:href="target_doc_URI#targetptr">...</link>
> 
> instead of
> 
> <olink targetdoc="target_doc" targetptr="targetptr">...</olink>
> 
> AFAIK stylesheet doesn't yet support this, but you can be almost sure 
> that support for such olinks will be added in a future.
> 
> Moreover xlink:href and linkend are presented on almost any 
> element, so 
> you can do things like:
> 
> <para><application 
> xlink:href="http://www.gnu.org/software/emacs/emacs.html";>Emac
s</application> 
> is the best editor.</para>
> 
> <para>Function <function linkend="strstr.reference">strstr</function> 
> can be used for substring searching.</para>
> 
> > We seriously want to use extended links, i.e., external 
> linkbases. In
> > 2001, XLink looked like a promissing technology, but since 
> then, most
> > of the XLink processors have disappeared. Anyone out there using
> > extended XLinks today?
> 
> I hear silence :-)
> 
> But there will be the extendedlink, arc and locator elements 
> in DocBook 
> 5. Is this sufficient for your needs? If not, could you 
> please describe 
> your needs in a more detailed way and provide some use case.
> 
> 				Jirka
> 
> -- 
> ------------------------------------------------------------------
>    Jirka Kosek     e-mail: jirka@kosek.cz     http://www.kosek.cz
> ------------------------------------------------------------------
>    Profesionální školení a poradenství v oblasti technologií XML.
>       Podívejte se na náš nově spuštěný web http://DocBook.cz
>         Podrobný přehled školení http://xmlguru.cz/skoleni/
> ------------------------------------------------------------------
> 
>