Hi Tim,
You are correct that there is no syntax in Epub2 to link from one Epub to another.
External linking for Epub3 is still under discussion and not included in the draft
standard, as far as I can tell. The general solution is difficult because of
uniqueness, file locations, etc.
However, I think there is still at least one case where active external links can
work. For example, if you build your guides for both HTML and Epub outputs, and put
the HTML up on a website, then the Epub user guide could link to the website version
of the admin guide. Many Epub readers can follow web links, either directly or by
forking off a browser.
This would require setting the baseuri of the "other" documents in the olink database
to the appropriate "http://..." value for each book so web link syntax is output for
those external links.
With the current epub stylesheets, a customization can turn off the active link while
still rendering the text from the olink database. The template named 'make.olink.href'
in common/olink.xsl handles forming the href string for each olink. If the olink
resolves in the database but that template returns a blank, then just the olink text
is output without a hot link.
If you use olinks only for external linking, then just making that an empty template
would do the job. However, if you use olinks for both internal links among modular
docs and for external links, then a more detailed customization is needed to preserve
the internal hot links. Your customization would need to compare the value of
'current.docid' to the targetdoc value of the olink, and return blank only if they
differ, otherwise return the href from the database.
I think selecting this behavior with a new stylesheet param for the epub stylesheets
would be a good new feature. In fact, it should probably be the default behavior, as
the website setup I described is a special case.
I think you would want to set the stylesheet param 'olink.doctitle' to 'yes' so that
external olink text includes a reference to the other book's title, otherwise readers
would not have enough context to interpret "Table 3.1".
Bob Stayton
Sagehill Enterprises
bobs@sagehill.net----- Original Message -----
From: "Tim Arnold" <
jtim.arnold@gmail.com>
To: <
docbook-apps@lists.oasis-open.org>
Sent: Monday, October 03, 2011 11:53 AM
Subject: [docbook-apps] cross-book olinks in epub
> hi,
> I'm using xsltproc with the 1.76.1 epub/docbook.xsl stylesheets. When
> creating a standalone epub doc, I get real hyperlinks for
> cross-document links.
>
> For example, see this page from the DocBook XSL Guide:
>
http://www.sagehill.net/docbookxsl/Olinking.html>
> Suppose you create an epub of the userguide; I believe it should not
> contain active hyperlinks to the admin guide.
> I think that such cross-document references should resolve as text-only.
> That is, a hyperlink that goes to an external docset should not be
> created for epub.
>
> That is just my opinion, I haven't read the official spec. But it
> seems unusable for an epub to retain relative links to an external
> document.
> Does that make sense? Am I misunderstanding?
>
> thanks,
> --Tim Arnold
>
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