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Thanks for the replies Ray and Rebecca. My original email had a copy-paste error. We have been using the correct v2 namespace (info:lc/xmlns/premis-v2). The real issue is that the namespace for the generic URI changed, invalidating our millions of XML documents referencing it. To avoid this problem going forward should the best practice be for users to always reference the version-specific schema? Through experimentation we discovered that this is the one for version 3 but we didn’t see it listed on the Premis website: http://www.loc.gov/standards/premis/v3/premis-v3-0.xsd

Thanks,
Andrea

From: PREMIS Implementors Group Forum <[log in to unmask]<mailto:[log in to unmask]>> on behalf of Rebecca Guenther <[log in to unmask]<mailto:[log in to unmask]>>
Reply-To: PREMIS Implementors Group Forum <[log in to unmask]<mailto:[log in to unmask]>>
Date: Friday, February 19, 2016 at 10:53 AM
To: "[log in to unmask]<mailto:[log in to unmask]>" <[log in to unmask]<mailto:[log in to unmask]>>
Subject: Re: [PIG] Premis v2/v3

It is also the case that when the version changes we make a copy of the schema and keep the latest version at www.loc.gov/standards/premis/premis.xsd<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_standards_premis_premis.xsd&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=oig9ldbD0NNVfVFKNDsg8dvl7BV-thv7T9mEwySr5Ng&e=>. The older schema then is still available at the URI in the appropriate versioned directory. So now that v3 is the current version that is what is at that generic URI.

Rebecca


On Feb 19, 2016, at 10:14 AM, Denenberg, Ray <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Andrea –

the PREMIS namespace was never   “http://www.loc.gov/premis/v2<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_premis_v2&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=ES3YmazoCAzkC6bbzUMPyp5h7Ow0wh6-GNP1LIaH0aY&e=>”  .

For v2  it is  “info:lc/xmlns/premis-v2”.   And yes, it has been changed for version 3, to  “http://www.loc.gov/premis/v3<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_premis_v3&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=B3bGm_vB3Vde1Sf69vJDg51kz4JM4b1J2dUt6JOMKGE&e=>” So not only did v2 change to v3, but it changed from an ‘info’ URI to an ‘http’ URI.

For schemas maintained at LC, the general rule is that minor version changes keep the same namespace (2.0, 2.1) but a major version change (2.x to 3.0) gets a new namespace.  Minor version changes are upward compatible; major version changes are not.

The namespace change from info to http:  in the early days of PREMIS, info URIs were popular and showed promise.  Today they are no longer in use, and virtually every namespace URI is http.

Ray Denenberg
Library of Congress


From: PREMIS Implementors Group Forum [mailto:[log in to unmask]] On Behalf Of Goethals, Andrea
Sent: Friday, February 19, 2016 9:45 AM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [PIG] Premis v2/v3

Dear Premis implementers,

Yesterday we discovered a problem with our repository's metadata descriptor files. What we discovered was that our Premis isn’t valid and we are trying to figure out if this is related to the release of Premis v3 (even though we are still on version 2).

In our descriptors we have been writing this schema location:
http://www.loc.gov/standards/premis/premis.xsd<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_standards_premis_premis.xsd&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=oig9ldbD0NNVfVFKNDsg8dvl7BV-thv7T9mEwySr5Ng&e=>

And this namespace:
 http://www.loc.gov/premis/v2<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_premis_v2&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=ES3YmazoCAzkC6bbzUMPyp5h7Ow0wh6-GNP1LIaH0aY&e=>

The problem is that the schema referenced above is requiring this namespace:
http://www.loc.gov/premis/v3<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.loc.gov_premis_v3&d=CwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=LPdSCPFhvO8mDmjvl_-JlDGPt3orxJrHLmT4bld8Hro&m=yFc9e5WwfHqHnTWFxyz55gkdM0cKkOhugHckg2hOVZg&s=B3bGm_vB3Vde1Sf69vJDg51kz4JM4b1J2dUt6JOMKGE&e=>

Unfortunately we have millions of descriptors now with invalid Premis. We didn’t notice this earlier because in production our tools reference locally-stored schemas. Was the Premis v2 schema URI repurposed for Premis v3?

Thanks,
Andrea

—
Andrea Goethals
Manager of Digital Preservation and Repository Services
Harvard Library