On Mon, 16 Apr 2001 13:01:02 David W Forslund wrote:
...
> > A question that I have is how it fits into to world of SOAP, XML-RPC etc? Are we suppose to send RDF documents from one system to another via SOAP? If that is the case, then is RDF an alternative to ebXML?
>
>RDF documents can be sent around just like any other XML documents.
Right. But since there are several competing formats for representing metadata, I thought it would be important to compare them. I found some discussion of RDF vs. ebXML in the ebXML-architecture list through Google, links to some of the relevant messages are listed below:
http://lists.ebxml.org/archives/ebxml-architecture/200005/msg00043.html
http://lists.ebxml.org/archives/ebxml-architecture/200005/msg00045.html
http://lists.ebxml.org/archives/ebxml-architecture/200005/msg00048.html
http://lists.ebxml.org/archives/ebxml-architecture/200005/msg00049.html
Expressing "metadata" can be complex and has many possible solutions, some of which are discussed in the
mail you have cited. It has been shown that RDF is a subset of UML (http://www.w3.org/TR/NOTE-rdf-uml)
More discussion of the extensive use of RDF is in:
http://xml.coverpages.org/rdf.html
DARPA has built a number of tools and extended RDF to DAML: http:://www.daml.org
Since the goal of the OIO Library is NOT just to exchange "project directories" :-), I thought it may warrant some attention from the participants of openhealth list.
For example, the OIO Library also supports exchange of OIO forms. Perhaps in the future, it will support exchange of GEHR archetypes, FreePM templates, and DTD from OpenEMed system? Maybe even translating between them?
We need to have some way of expressing these templates (or even translating between different template "languages".
So, I hope we can collectively consider what a reasonable metadata exchange mechanism will be. The "projects database" data exchange will be the pilot application, if you will.
Hopefully when it is done, Minoru and LinuxMedNews will be willing to participate in testing it. :-)
> > Finally, as a first step in implemening RDF, is it a good idea to install a "button" on each folder and entry in the OIO Library so that the content of that folder or entry will be downloaded as a RDF document when the "button" is pressed?
>
>I don't know that that means.
Sorry. Let me explain.
The OIO Library is a metadata / data repository. Once a particular piece of metadata or data has been discovered by the user, it should be downloadable in a convenient format. Currently, all entries in the OIO Library can be "viewed"/rendered for the web-browser client. This is fine for previewing an OIO-form and reading the description and linking to a project's home page. However, for portability to another OIO Library or a non-OIO Library content server, we need an XML or RDF data export/import mechanism.
So the OIO Library ought to have a way of requesting the metadata in an RDF form. This could be very important for computers talking to computers rather than presenting the information to a person.
Currently, I am using OIO's forms XML format for the import/export of OIO forms metadata. That works fine for exchanging OIO's plug-and-play web-forms. However, the big question is what format we should use for other types of metadata / data? Should we use RDF?
Regardless, a "button" will be placed on the webpage that describes the selected "object". Once that button is clicked, the RDF or OIO-form will be downloaded! That is what I was referring to.
But this seems to me to be the last step in the process. Adding a button for downloading in a particular format is easy, but deciding how to express metadata is the important part.
>RDF should be used as a way of
>documenting the metadata used in a "form" or some other xml document.
Are you saying that the user should download both a RDF and another XML document? Kind of like DTD + XML document?
Something like this. XMI is certainly an alternative to this, but is considerably more verbose. But it should be possible to provide a one-to-one mapping between XMI and RDF.
>This can be used to validate the data, if needed. It provides more than
>a DTD does in that it allows one to describe the semantics of the
>information.
This makes sense but all the RDF examples that I have seen seem to embed content information right in the RDF.
The same is true for XMI. Metadata containers can contain content, too. It may take discipline to just have the metadata. The same applies to any XML document. What is the meaning of a template?
---------------------------
For example from (http://www.dlib.org/dlib/may98/miller/05miller.html):
<?xml:namespace ns = "http://www.w3.org/RDF/RDF/" prefix = "RDF" ?>
<?xml:namespace ns = "http://purl.oclc.org/DC/" prefix = "DC" ?>
<?xml:namespace ns = "http://person.org/BusinessCard/" prefix = "CARD" ?>
<RDF:RDF>
<RDF:Description RDF:HREF = "http://uri-of-Document-1">
<DC:Creator RDF:HREF = "#Creator_001"/>
</RDF:Description>
<RDF:Description ID="Creator_001">
<CARD:Name>John Smith</CARD:Name>
<CARD:Email>[EMAIL PROTECTED]</CARD:Email>
<CARD:Affiliation>Home, Inc.</CARD:Affiliation>
</RDF:Description>
</RDF:RDF>
---------------------------
So, although it can serve as metadata for another document, an RDF document seems to be just another representation of the same information in the other document. In the case of the OIO Library, all the information are in the relational database anyways. So, it boils down to generating an RDF document or a HTML document from the same data source? If the OIO Library generates a RDF document describing OpenEMed, for example, why should it also generate another XML document describing OpenEMed?
I'm not sure of the meaning of your question. It is valuable to have a Metadata repository (a la the MOF of the OMG) which only contains descriptions of the data contained (in a much smaller container) separate from the actual data.
That is what people are trying to do in creating templates or archetypes. The real data would be validated against the
metadata much like it is with a DTD.
Dave
Am I missing something?
Thanks in advance,
Andrew
---
Andrew P. Ho, M.D.
OIO: Open Infrastructure for Outcomes
www.TxOutcome.Org
Assistant Clinical Professor
Department of Psychiatry, Harbor-UCLA Medical Center
University of California, Los Angeles
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Computer and Computational Sciences
Los Alamos National Laboratory
505-665-1907
