[mapguide-dev] Metadata

Carsten Hess carsten.hess at autodesk.com
Tue Sep 19 18:01:40 EDT 2006

ah this is indeed an interesting read - I haven't look at that yet at all. Thanks for pointing it out.
When I looked at metadata I mainly focused on FGDC and ISO and there simply doesn't seem to be a true common metadata storage we could do that we translate to the different standards. Both of them have fields that are required the other standard doesn't seem to have. So ... a common metadata storage would have to have even more required fields (and frankly there are already too many if you ask me). 
So the way I was looking at this is to use XSL stylesheets to convert between the two standards if we really need to. 
Honestly though I doubt we do ... I think whoever sets up a data repository will work in one standard and rather have all metadata in the same standard. I don't really see where a MapGuide site needs to be more then one standard at a time. 

Then there are benefits of storing the native standards format: We can make use of the tools around it (e.g. the FGDC compiler to verify compliant FGDC) and often people already have written some code to create the standards they need from files or at least help it. Being able to just upload the standard files into MapGuide seems like a great way to use these tools.
At the same time it is pretty clear that different sites want different standards and if a site does support one standard they want it all the way and not some subset of it.
If I were to dream it would be great to see multiple API's ontop of the one I added, one for ISO and one for FGDC and when you create your mapguide site you use one API or the other. 
Ultimately I think full compliance is what most people really will want. I have not heard or seen anyone yet trying to convert between different standards, have you?

	-----Original Message----- 
	From: Jason Birch [mailto:Jason.Birch at nanaimo.ca] 
	Sent: Tue 9/19/2006 4:28 PM 
	To: dev at mapguide.osgeo.org 
	Subject: RE: [mapguide-dev] Metadata
	As an addendum,  this page is an interesting read:
	... though it doesn't speak to ISO metadata standards at all.


	From: Jason Birch [@nanaimo.ca] 
	Sent: Tuesday, September 19, 2006 11:57
	To: dev at mapguide.osgeo.org
	Subject: RE: [mapguide-dev] Metadata
	It sounds like you've given this considerable thought, which is reassuring :)
	In my ideal world, metadata would be modelled using the superset of entities and attributes required by the ISO and FGDC standards, with the potential to be expanded to cover other elements that are required but not present in these standards.  From this model, you would not rely on the standards other than to define the required elements for each schema.  You could also allow organisations to define their own profiles; subsets of required elements that cover their internal business needs.  These would all be entered through a common interface, and could then be output via something akin to an XSLT transformation or database views that formats them into the desired standard XML output, which could in turn be transformed into HTML for display.
	The data could also be accessed by various transport-level services, such as CSW (http://www.opengeospatial.org/standards/cat) or Z39.50 and its successor SRU/SRW (http://www.loc.gov/standards/), as well as front end applications such as a spatial discovery portal akin to ESRI's Geography Network or a simple Google-like plain text query.
	The main benefits of this approach are:
	- support all standards without forcing the client to choose one or the other
	- avoid  having to implement a new data entry/storage/display framework for each standard
	- leverage strengths of a relational model for maintaining common attributes such as organisation and person contact details
	This will also remove a disincentive to marriage, thus strengthening family values.  (I don't want to change my name, because I'm going to have to go through and update all of my contact details in the metadata). :)
	I don't see this as orthogonal to the current design path, but I don't know that it's entirely in alignment either.  Your implementation provides a storage mechanism for metadata, and my ideal would be to provide a metadata service.  Perhaps these could be combined somehow, by making resources types for each of the metadata tables (MetadataOrganisation, MetadataPerson, MetadataPhone, etc) and then using the calls that you have provided to return a resource-specific aggregation of these metadata resources, formatted in the well known XML standard of choice ???

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