Benno Blumenthal wrote:
Ethan Davis wrote:
Hi Benno,
I've updated our main static catalogs to include xlink:type="simple".
Haven't dealt with our generated catalogs yet.
Since all the uses of xlink in the InvCatalog schema at this point
are simple xlinks, I was thinking it would be a convenience to
provide a default value for xlink:type. That way all existing
catalogs would automatically be complient with the XLink spec. At
least they would look that way if the application was paying
attention to the DTD/XSD. As with most default values in XML docs, I
think explicitly including xlink:type="simple" in our catalog
documents is the way to go. Just hoping to buy us some pain free
complience.
My knowledge of XML is very limited, so please help me out here. My
understanding of namespaces was that the href in the namespace was
just a URI, i.e. an unique identifier, not a file to be read. In
other words, a program can sort out the different name spaces without
ever actually reading the files referenced. If one can put default
values in a DTD (and presumably in a schema), then that would have to
be read before the file could be "understood". So you are saying
that Mozilla is required to read the dtd and/or schema before parsing
the document? and if we put in default values for the xlink:type, the
Xlink aware code would use that default value even though it does not
understand much else in the thredds schem(a)? If so, that would be
pretty interesting.
That's right, XML namespaces are just unique identifiers. Documents can
give hints on the location of schemas but don't have to and that info
can just be ignored anyway. So, Mozilla isn't required to read DTDs or
schemas and I'm sure it doesn't try to validate much if any XML. I was
just thinking a default value is a really easy change and might be
useful to some applications. But now that you mention Mozilla again, I
realize that there probably aren't many general applications that
validate against DTD/schema so adding a default value may not be very
useful. Other than XML parsers, editors, and such, I'm guessing only
THREDDS aware applications will use the THREDDS schema.
I was just looking at your catalog at
http://iridl.ldeo.columbia.edu/SOURCES/thredds.xml
I see the xlink:type attributes but not the CSS stuff
(<?xml-stylesheet type="text/css" href="threddsstyle.css" ?>). Do you
have an example that does include that? Also, can you point me to
your threddsstyle.css so I can take a look at it?
Yes, it is not there yet. css is pretty limited -- probably cannot do
anything really useful with it (i.e. my current version mostly messes
things up), but it is interesting because it handles namespaces. And
because it shows that mozilla "understands" xlink. Here is my
example (which should appear on the site tomorrow when I can install a
new version).
@namespace threddsv06 url(http://www.unidata.ucar.edu/thredds);
@namespace thredds
url(http://www.unidata.ucar.edu/namespaces/thredds/InvCatalog/v1.0);
@namespace xlink url(http://www.w3.org/1999/xlink);
@namespace mods url(http://www.loc.gov/mods/v3);
thredds|dataset {display:block; padding-left: 40px; list-style-type:
disc;}
thredds|dataset:before {display:block; text-indent: -40px;
font-weight:bold; content: attr(name)}
thredds|catalogRef:before {display:block; text-indent: -40px;
font-weight:bold; content: attr(xlink|title)}
thredds|catalogRef {display:block; padding-left: 40px;
font-weight:bold;}
thredds|dataset documentation{ display:list-item; font-weight:normal;
color:green;}
thredds|dataset *{display:listitem; font-weight:normal;}
thredds|catalogRef documentation{ display:list-item;
font-weight:normal; color:brown;}
thredds|catalogRef *{display:inline}
threddsv06|dataset {display:block; padding-left: 40px;
list-style-type: disc;}
threddsv06|dataset:before {display:block; text-indent: -40px;
font-weight:bold; content: attr(name)}
threddsv06|catalogRef:before {display:block; text-indent: -40px;
font-weight:bold; content: attr(xlink|title)}
threddsv06|catalogRef {display:block; padding-left: 40px;
font-weight:bold;}
threddsv06|dataset documentation{ display:list-item;
font-weight:normal; color:green;}
threddsv06|dataset *{display:listitem; font-weight:normal;}
threddsv06|catalogRef documentation{ display:list-item;
font-weight:normal; color:brown;}
threddsv06|catalogRef *{display:inline}
mods|mods{display:block; color:black}
mods|mods
role,originInfo,typeOfResource,identifier,caption{display:none;
color:green}
mods|mods relatedItem:before {color:black; content: " in "}
mods|mods part detail[type="volume"]
{display:inline;font-weight:bold; color:brown}
mods|mods part detail[type="issue"]
{display:inline;font-style:italic; color:brown}
mods|mods part detail[type="issue"]:before {content: "("}
mods|mods part detail[type="issue"]:after {content: ")"}
mods|mods part extent[unit="page"]:before {content: "pp"}
mods|mods part extent[unit="page"]:before {content: "pp"}
mods|mods subTitle:before {content: "--"}
mods|mods end:before {content: "--"}
mods|mods part:after {content: "."}
mods|mods titleInfo{font-style:italic;}
Note that I was contemplating inserting a mods namespace for
references, which is why the mods tags were there.
However, one could alternatively specify an XSLT stylesheet, which
should be able to render a THREDDS xml file usefully. And one could
use javascript if necessary to create buttons, etc.
But I have not gotten there yet.
OK. Thanks for the CSS.
Ethan
Benno
Thanks,
Ethan
Benno Blumenthal wrote:
Ethan Davis wrote:
Hi Benno,
I will go through our catalogs and add the xlink:type attribute.
I'll also add it to our catalog generation tools.
That would be great.
In the InvCatalog 0.6 spec xlink:type had a default value of
"simple". Looks like that got dropped in 1.0. Does adding this as a
default seem like a good idea? Or would requiring it but no default
value be preferable?
my reading of xlink is that xlink:type is required, and the way we
are using xlink its value is "simple".
There is no provision for a default value.
The reason for doing this is so that we can build on top of software
that already understands xlink, which, if we have not written it, is
expecting xlink:type="simple" before processing it.
Benno
--
Ethan R. Davis Telephone: (303) 497-8155
Software Engineer Fax: (303) 497-8690
UCAR Unidata Program Center E-mail: edavis@xxxxxxxx
P.O. Box 3000
Boulder, CO 80307-3000 http://www.unidata.ucar.edu/
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