32833 - Implement ID/IDREF(S) linking

Status: RESOLVED WONTFIX

(Core :: XML, enhancement, P3)

Description

[Heikki Toivonen (remove -bugzilla when emailing directly)]

ID/IDREF(S) is the basic form of XML linking:

<?xml version="1.0"?>
<!DOCTYPE memo [
<!ATTLIST ref
          xref IDREF #REQUIRED
>
<!ATTLIST para
          unique ID #IMPLIED
>
]>
<memo>
<title>Title here</title>
<para>Here is a <ref xref="id1">link</ref> .</para>
<para unique="id1">This is the link target.</para>
</memo>

A linking element is recognized by noticing that it has a non-empty attribute
whose type is either IDREF or IDREFS (IDREFS is the plural, several link targets
can be specified in one attribute, separated by spaces). Currently there is no
support for this in the parser nor in the DOM.

A target can be an element with a unique id (a non-empty attribute whose type is
ID). Currently there is no support for this in the parser (see bug 10292), but
DOM 2 at least should have the GetElementById method in the DOMDocument
interface (this is not yet implemented).

ID/IDREF(S) linking enables linking inside a document, it cannot be used to link
to other documents.

Comment 1

[Heikki Toivonen (remove -bugzilla when emailing directly)]

I now have CVS account, assigning XML linking related bugs to me 
([e-mail]).

Comment 2

[Heikki Toivonen (remove -bugzilla when emailing directly)]

How should we inform the user about IDREFS links that have multiple targets?

I think I have the solution for the case when the link has been clicked: provide 
a popup menu listing all the targets. The user must select the target s/he 
wishes to travel to.

The problem is with mouse over. What to show in the status bar? Normally we show 
the full URI, but if there are several IDREFS targets we quickly run out of 
space... Should we show a tooltip with all the targets? If so, there is still 
the problem with status bar.

I added Ian Hickson to CC because he has had good and related comments in bug 
1995.

Comment 3

[Hixie (not reading bugmail)]

Well, the full URI is always in this document, isn't it? So there won't be much
to show in the status bar anyway.

   http://www.foobar.net/somewhere/page.xml#one, #two, #three, #four

...or just:

   #one, #two, #three, #four

...in fact.

Comment 4

[Nisheeth Ranjan]

Setting target milestone to Future so that this does not show up on PDT's 
radar...

Comment 5

[Heikki Toivonen (remove -bugzilla when emailing directly)]

With the new Expat we should have the ID part covered, but that still leaves
IDREF(S). James Clark said in an email that his new Expat does not/will not(?)
include support for IDREF(S) attribute(s). We would need to add that ourselves I
guess.

Comment 6

[Anne (:annevk)]

Per https://dom.spec.whatwg.org/ we should only support an id attribute.