I would argue that it is very difficult to create anything but a single
hyperlink with a simple-type linking element such as <extptr> or <extref>
because you can't create or establish any real *relationship* between the
elements because they are siblings. How could you represent this type of
link using simple-type elements?
<a href="largeimage.jpg" target="_blank">
<img src="smallimage.jpg" alt="image"/>
</a>
You could use a combination of <extptr>/<extref> (etc.) elements, one
element set to show="embed" (I suppose this could imply that this is the
<img> element in HTML) and another set to show="new" (or "replace").
However, what about the scenario where you want the first element to just
be an embedded image, and the second element doesn't have any connection
to the first element? You would need some type of term that identifies
(or disassociates) this relationship. So I think it could be just as
cumbersome to do this as to use an extended-type linking element where you
can establish the relationship between resources, even with single,
uni-directional outbound links.
In fact, using this scenario, you could create any number of embedded
images and link out from any selected number of them using an <arc>
element to establish to relationship between resources. In this example,
the first and third images are just embedded images, while the second
image is embedded and also links out to another image.
<img src="firstimage.jpg" alt="image"/>
<a href="linkout1.jpg"><img src="secondimage.jpg" alt="image"/></a>
<img src="thirdimage.jpg" alt="image"/>
So we only want to link out from the second image. We could represent
that like this:
<daogrp>
<resource label="start1"/>
<resource label="start2"/>
<resource label="start3"/>
<daoloc label="image1" role="image/jpeg" href="firstimage.jpg"/>
<daoloc label="image2" role="image/jpeg" href="secondimage.jpg"/>
<daoloc label="image3" role="image/jpeg" href="thirdimage.jpg"/>
<daoloc label="link2" role="image/jpeg" href="linkout2.jpg"/>
<arc from="start1" to="image1" show="embed" actuate="onload"/>
<arc from="start2" to="image2" show="embed" actuate="onload"/>
<arc from="image2" to="link2" show="new" actuate="onrequest"/>
<arc from="start3" to="image3" show="embed" actuate="onload"/>
</daogrp>
This may seem needlessly complex, but the trade-off is that we have now
established the exact relationship between resources. There is no
question as to which links belong together and how each is to be
traversed.
If you never need to get any more complex that creating a single embedded
image or a single hyperlink, then I agree that this is way more work than
it is worth. But if you want to go beyond the basics and really extend
the capabilities of EAD and XML, then I think my ideas are worth
considering, even in the present environment.
Mark
On Mon, 20 Sep 2004, Fox, Michael wrote:
> Mark,
> Thank you for sharing this interesting document. I have several
> comments in response to the useful issue you raise.
>
> 1. While it is both true that XLink is the linking mechanism for XML
> and that it can be used for simple and extended links, the truth is that
> the environment in which we are now working is actually a mixture of XML
> and HTML and that the linking capability we have is limited to the
> simple links now possible in HTML. I am still waiting to see an all XML
> environment where XLink actually functions in a global way and extended,
> bi-directional links are possible.
>
> 2. If this is the case, the use of XLink syntax to generate simple,
> uni-directional HTML links is needlessly complex and unnecessary. It is
> hardly necessary to generate the proper HTML output that would result
> from a transformation. Theoretically interesting to be sure. Am I
> missing something here?
>
> 3. Your chart associates <extref> solely with the HTML <a> element but
> it might also need to generate an <img> element where the text in
> <extref> is used to produce a caption for an external image rather than
> the link text in an <a>. The differentiation of these two possible
> outcomes, an HTML <a> or an HTML <img> in an HTML transformation, is the
> reason why one needs the embed and new values in the show attribute with
> <extptr>.
>
> Michael Fox
>
>
>
>
>
>
>
> -----Original Message-----
> From: Encoded Archival Description List [mailto:[log in to unmask]]On Behalf Of
> Mark Carlson
> Sent: Friday, September 17, 2004 8:03 PM
> To: [log in to unmask]
> Subject: Re: daoloc attribute
>
>
> I don't believe this is true. XLink forms the basis for all linking
> elements in XML, both simple (extptr, etc.) and extended (daogrp, linkgrp,
> etc.). In the XLink specification, section 2.1, it states that "one of
> the common uses of XLink is to create hyperlinks". A standard <A>
> hyperlink is called an "outbound" link in XLink and that type of link can
> be created with a simple-type linking element or, as per section 5.2
> states, using as extended link to create simple link functionality (see
> example in this section "Simple Link Functionality Done with an Extended
> Link"). But using an extended link in this way requires additional
> elements since the "behavior" attributes are contained in the <arc>
> element in EAD. (Section 5).
>
> A document I'm working on presents one interpretation for how this could
> be implementated using today's tools (for simple outbound links, that
> is).
>
> I would be interested in comments.
>
> http://staff.washington.edu/carlsonm/XLinkToEAD.pdf
>
> Mark
>
> On Fri, 17 Sep 2004, Fox, Michael wrote:
>
> > I have been intrigued by this thread with respect to the <daoloc> element. It is my understanding that this element is applicable only as part of an implementation of bi-directional links within an XLink-enabled technology and I was unaware of any broadly based implementation of same. If someone is using it, I would appreciate a pointer to the application as I've always wondered how this standard would play out in real life.
> >
> > Michael
> > -----Original Message-----
> > From: Encoded Archival Description List [mailto:[log in to unmask]]On Behalf Of Druscie Simpson
> > Sent: Friday, September 17, 2004 1:13 PM
> > To: [log in to unmask]
> > Subject: Re: daoloc attributes
> >
> >
> > Dietra,
> >
> > Ashley is working on this as well. She received some code from Kathy Wisser, but, while it works just fine on Kathy's PC, it doesn't work on Ashley's! Check with Ashley on Monday to see where she is on this.
> >
> > Druscie
> > _____________________________________________________________
> > Druscilla R. Simpson
> > Head, Information Technology Branch
> > N.C. State Archives
> > (919) 807-7319 (voice)
> > (919) 733-1354 (fax)
> > [log in to unmask]
> >
> > Opinions expressed in this message may not represent the policy of this
> > agency. E-Mail to and from me, in connection with the transaction of public
> > business, is subject to the North Carolina Public Records Law and may be
> > disclosed to third parties.
> >
> > ----- Original Message -----
> > From: Dietra Stanley <mailto:[log in to unmask]>
> > To: [log in to unmask]
> > Sent: Friday, September 17, 2004 12:11 PM
> > Subject: Re: daoloc attributes
> >
> > Hey John can you please forward me his reply...I am having significant difficulty in adding dao's into my document also.
> >
> > Do you have a copy of what code i need to add to the style sheet and the dtd files in order for them to recognize i am inserting a dao into my xml.
> >
> > gee thanx for any help
> >
> > dietra lynn
> > ----- Original Message -----
> > From: Hyslop, John <mailto:[log in to unmask]>
> > To: [log in to unmask]
> > Sent: Friday, September 17, 2004 11:34 AM
> > Subject: Re: daoloc attributes
> >
> > Thanks to Nick Mangine my confusion has been cleared up.
> >
> > John Hyslop
> > Assistant Division Manager
> > Long Island Division
> > Queens Borough Public Library
> > 89-11 Merrick Boulevard
> > Jamaica, New York 11432
> > (718)990-0770
> >
> > These opinions are my own and not those of the Queens Borough Public Library
> >
> > -----Original Message-----
> > From: Hyslop, John [mailto:[log in to unmask]]
> > Sent: Friday, September 17, 2004 10:17 AM
> > To: [log in to unmask]
> > Subject: daoloc attributes
> >
> > I'm a bit confused and a novice so bear with me. In the EAD Application Guidelines Version 1.0, Figure 7.6c page 230 shows the daoloc element having the actuate and show attributes. However the EAD DTD doesn't allow them and the Tag Library doesn't list them. Why?
> >
> >
> > John Hyslop
> > Assistant Division Manager
> > Long Island Division
> > Queens Borough Public Library
> > 89-11 Merrick Boulevard
> > Jamaica, New York 11432
> > (718)990-0770
> >
> > These opinions are my own and not those of the Queens Borough Public Library
> >
> >
>
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