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Robert Wolfe, MIT Libraries
William Reilly, MIT Libraries
Acknowledgements
This document was prepared with the assistance of:
MacKenzie Smith, MIT Libraries
Rob Tansley, Hewlett-Packard
Larry Stone, MIT Libraries
Margret Branchovsky, MIT Libraries
Introduction
Reference Model for Open Archives Information Systems (OAIS)
DSpace at MIT has implemented the Reference Model for Open Archival Information Systems (OAIS) http://nssdcftp.gsfc.nasa.gov/standards/ccsds/pdf/CCSDS-650.0-B-1.pdf. DSpace's implementation has identified a need to prepare a METS profile or profiles that will govern the creation of the three types of content "packages" defined by the reference model.
This profile is intended to provide a complete set of instructions for the preparation of OAIS Submission Information Packages (SIPs). The purpose of this SIP profile is to make creation of SIPs as easy as possible for DSpace content partners. Many of these content partners will be other DSpace instances. In this case, the SIP profile may also serve as an OAIS Dissemination Information Package (DIP) profile. Future use of this profile, or related profiles, to govern the creation of Archive Information Packages (AIPs) will require the inclusion of additional information to account for the larger information needs of AIPs.
DSpace Content Object Model
In order the make easier the preparation of conformant SIPs, the DSpace Content Object Model is here mapped to the METS object model.
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7. Preferred Bitstream = METS <file> element @USE (Structural Requirements #)
There are some potential DSpace Items that are not websites--they do not have a primary bitstream--that need to show preference for one bitstream or file above all others. One example of this is a potential item that contains three versions of the same document (e.g. pdf, ps and latex). It is advantageous to the user to know that the pdf is the version intended for public consumption. In this case this profile recommends that USE attribute of the <file> element representing the preferred bitstream contain the value "preferred".
Descriptive Metadata
As outlined in Rules of Description #1 and #2, the DSpace has adopted the Metadata Object Description Schema (MODS) as a transfer schema for descriptive metadata in SIPs.
As declared in Structural Requirements #16, DSpace requires just one MODS record that describes the entire item. This MODS record will be deposited into the DSpace Metadata Tables. This profile also recommends the inclusion of other metadata records where they exist. These records may describe discrete parts of the DSpace Item like single files, they may also record Item metadata in another schema native to system authoring the SIP. Future versions of this profile will address the use of the GROUPID attribute of the <dmdSec> element in coordination with the DMDID (IDREF) attribute to associate multiple records in different schemas. For now, any other metadata that is included in the SIP will not be processed into the metadata tables, but will be remain associated with the Item.
Technical Metadata
DSpace has defined a Technical Metadata Element Set to fulfill their preservation and content lifecycle management information needs. This Technical Metadata Element Set is best expressed using the PREMIS Preservation Metadata Schema: Object. DSpace use of the PREMIS Data Dictionary to represent needed technical metadata elements does not constitute full implementation of the PREMIS data model.
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- Do you as a content provider have this information?
Panel - If you do not have it, DSpace will create some of this information upon ingestion of the package.
- If you do have this information, its inclusion is still optional but strongly recommended.
Panel - If you can, write both.
- If you can't write both, write the <techMD> using PREMIS elements.
- If you can't write that, write the attributes in the <file> element.
DSpace Bitstream Metadata
In the use case where one DSpace instance uses this profile to create a SIP intended for a second DSpace instance it would be useful to include metadata the DSpace captures for each bitstream. There are three semantic units that DSpace captures: name, source and description. The appropriate metadata schema for transferring this information is currently under investigation.
In addition DSpace assigns a Sequence ID to each bitstream. These sequence IDs may look like handles, but they are not handles and will not resolve via the Handle system. The appropriate means to include Sequence IDs in bitstream metadata is under investigation for the DSpace-2-DSpace use case. If Sequence IDs are included in a SIP, every bitstream would require a unique sequence ID to avoid collision with a DSpace import mechanism that will assign a Sequence ID to any bitstream lacking one.
Rights Metadata
The DSpace Item Submission interaction provides an opportunity to assign a Creative Commons license to the material deposited in the repository. In this METS SIP profile the same opportunity is provided. Inclusion of CC licenses as rdf/xml is encouraged, but not required, in Rules of Description #11. An example of CC license metadata is included in the sample METS document in the Official XML Expression of the METS SIP Profile.
The DSpace Deposit License is not required for METS documents that conform to this SIP Profile. It is assumed that agreement concerning this license between DSpace and its content providers will be accomplished elsewhere than the submission package.
Official METS Profile Documentation
The following are the necessary component parts of any METS profile conforming to the METS Profile Schema as defined at http://www.loc.gov/standards/mets/profile_docs/components.html
These parts are presented first in human readable form, then repeated in an requirements compliant xml expression. The xml expression is governed by the schema at: http://www.loc.gov/standards/mets/profile_docs/mets.profile.v1-2.xsd
URI
Title
DSpace METS Document Profile for Submission Information Packages (SIP)
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2. Metadata Files should be encoded in xml and should validate to the schema corresponding to the mdType attribute value of the mdRef element.
Tools and Applications
1. This profile is intended for use with the DSpace Packager Plugin, sometimes called the Lightweight Network Interface and discussed at http://wiki.dspace.org/index.php/PackagerPlugins.
Examples
DSpace to DSpace Example
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