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Hi Michele,

I'll reply to you off the list for now, but will respond on the list later.  Most XML authoring environments will fetch a DTD stored on a remote server over HTTP to drive validation, etc.  However, I had no idea that the EAD 2002 DTD and entity files are being served from a FTP server.  I doubt that most authoring kits would fetch from FTP (I could be wrong about that).

At any rate, there's no reason on LC's end to /not/ have these served over HTTP instead of FTP.  This would allow you to use a HTTP URI in your instance and call the DTD remotely.  The only obvious downside to this is if someone needs to add a custom element, entity reference, etc.  Then they'd have to download the DTD and entity files for local storage.  

Glenn Gardner is going to check with Daniel Pitti, Kris Kiesling, Michael Fox, et al. to see if there's a historical reason why FTP is being used.  If not, we'd like to switch over to HTTP.  

Thanks, and we'll write to the list after we hear from Daniel et al.

Clay

~~~~~~~~~~~~~~~~~~
Clay Redding
Digital Project Coordinator
Network Development & MARC Standards Office
Library of Congress
LA308, Mail Stop 4402
101 Independence Ave. SE
Washington, DC 20540
[log in to unmask]
202-707-7196 
~~~~~~~~~~~~~~~~~~
>>> Michele R Combs <[log in to unmask]> 01/14/10 11:23 AM >>>
In the past I've tried using the LOC location for the DTD but it hasn't worked.  Should it?  If so what is the correct URL so I can try it again?

Thanks --

Michele

-----Original Message-----
From: Encoded Archival Description List [mailto:[log in to unmask]] On Behalf Of Clay Redding
Sent: Thursday, January 14, 2010 10:22 AM
To: [log in to unmask]
Subject: Re: Schema Comment: xsi:schemaLocation

Hello Dirk,

Yes, you are exactly right, that the syntax is:

<ead xmlns="urn:isbn:1-931666-22-9" xmlns:xlink="http://www.w3.org/1999/xlink"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     audience="external"                                  
     xsi:schemaLocation="urn:isbn:1-931666-22-9 http://www.loc.gov/ead/ead.xsd">

The question of whether the server can handle it is a legitimate concern, but luckily our servers have handled the hits for this schema and our numerous others with little effort.  In the past LC has encountered problems when using URIs directly to W3C schemas, and at times the W3C would cut off block our IPs from access until the matter was resolved.  This isn't a concern for the EAD XML Schema.

Caching the schema in your local environment is a good practice to ensure that the schema is available to you in case of a network outage.  Oxygen XML Editor, for example, offers a validation utility that caches the schema on the first validation attempt, and calls against the local stored copy for subsequent validation attempts.  Most importantly, doing this doesn't require any change in the xsi:schemaLocation URI.

Hope this helps,
Clay

~~~~~~~~~~~~~~~~~~
Clay Redding
Digital Project Coordinator
Network Development & MARC Standards Office
Library of Congress
LA308, Mail Stop 4402
101 Independence Ave. SE
Washington, DC 20540
[log in to unmask]
202-707-7196 
~~~~~~~~~~~~~~~~~~
>>> <[log in to unmask]> 01/14/10 9:28 AM >>>
Hello,

I have heard it say that one is supposed to declare an EAD schema like
more or less so:


<ead xmlns="urn:isbn:1-931666-22-9" xmlns:xlink="http://www.w3.org/1999/xlink"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     audience="external"                                  
     xsi:schemaLocation="urn:isbn:1-931666-22-9 http://www.loc.gov/[...]/[...].xsd">


Supposedly the loc.gov url, rather than a local uri, should be used in
order to discourage institutions from using their home-brewed, ever so
slightly moderated, versions. Can someone confirm that the LOC servers
are capable of handling all the hits that this wil entail? In that case
the real url probably could be published.


Cheers,

Dirk van Laanen