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PAWN: A Novel Ingestion Workflow Technology for Digital Preservation

PAWN: A Novel Ingestion Workflow Technology for Digital Preservation. Mike Smorul, Joseph JaJa, Yang Wang, Mike McGann, and Fritz McCall. Overall Principles. Consistent with the Open Archival Information System (OAIS) model Distributed, secure ingestion

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PAWN: A Novel Ingestion Workflow Technology for Digital Preservation

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  1. PAWN: A Novel Ingestion Workflow Technology for Digital Preservation Mike Smorul, Joseph JaJa, Yang Wang, Mike McGann, and Fritz McCall

  2. Overall Principles • Consistent with the Open Archival Information System (OAIS) model • Distributed, secure ingestion • Use of web/grid technologies – platform independent • Minimal client-side requirements • Ease of integration with archival storage or data grid systems.

  3. Producer

  4. Producer • Provides data to an Archive based on a prior agreement. • Consists of a management/metadata server and an ingestion client. • Provides initial arrangement, context, and metadata.

  5. Archive - receiving

  6. Archive – receiving • Receives data from a Producer • Validates bitstreams and metadata, and sends acknowledgement to Producer. • Arranges into collections and specifies preservation policy. • Publishes bitstreams into a digital archive.

  7. Archive – Long term preservation • Implemented using grid technologies. • Use the existing prototype NARA/UMD/SDSC site. • Automated replication and integrity checking. • Enforces access control and preservation policy

  8. Ingestion Workflow • Negotiate Submission Agreement. • Workflow Initialization and Submission Information Packet (SIP) creation. • Transfer of SIPs to archive. • Validation of SIP transfer • Organization of data into collections and transfer into persistent archive.

  9. Submission Agreement • Based on data appraisal and record schedule, including format and metadata. • Create machine actionable set of rules describing items. • Final Submission Agreement is composed of: • METS document for application defaults • METS Constraint document to limit METS form to submission parameters

  10. METS Overview • Provides a framework for linking structural organization of objects with metadata. • Using XML namespace, metadata from various XML schema can be attached to objects • Ie, dublin core, FGDC, etc • Extensible for more complex metadata • http://www.loc.gov/standards/mets/

  11. Sample METS Document

  12. Why METS Constraints? • METS doesn’t provide a way to create machine interpretable rules describing a collection • Ie: allow only JPEG files in certain structural areas • METS profiles allow for developer interpretable rules, not machine interpretable

  13. METS Constraints • Allows structural, metadata, and file constraints. • Structural Constraints: • Restrict child div’s and restrict pointers to div, file, and other mets documents • File Constraints: • Restrict files by mime-type or validation tests • Metadata Constraints: • Restrict allowed metadata schema.

  14. METS Constraints - Template <?xml version="1.0" encoding="UTF-8"?> <mets …. > <!-- validation test section, referenced in the constraints document --> <amdSec> <techMD ID="xmltest"> <mdWrap MDTYPE="OTHER"> <xmlData> <val:validation NAME="xmltext" DESCRIPTION="Test for valid xml documents" MIMETYPE="text/xml"> <val:valgrp required="true"> <val:valtest name=“xml" required="true"> <val:description>generic xml test for any file</val:description> </val:valtest> </val:valgrp> </val:validation> </xmlData> </mdWrap> </techMD> </amdSec> <!-- base div structure to use for all clients --> <structMap> <div ID="ID1" LABEL="Research &amp; Development Records"> <div ID="ID1.1" LABEL="Research &amp; Development Project Records"> <div ID="ID1.1.1" LABEL="R&amp;D Project Case Files"/> <div ID="ID1.1.2" LABEL="R&amp;D Record Series"/> </div> </div> </structMap> </mets>

  15. METS Constraints - Rules <?xml version="1.0" encoding="UTF-8"?> <metsconstraint …> <filegrp ID="FILE1" NAME="Text Document"> <!-- Files can be identified either by MIMETYPE, or TESTID in skeleton METS document or both --> <file NAME="html document" MIMETYPE="text/html"/> <file TESTID="xmltext" NAME="xml document" MIMETYPE="text/xml"/> </filegrp> <!-- Apply rules to predefined div's and link to required file/metadata tests above --> <divrule DIVID="ID1" RESTRICTDIV="true" RESTRICTFTPR="true" RESTRICTMPTR="true"/> <divrule DIVID="ID1.1" RESTRICTDIV="true" RESTRICTFTPR="true" RESTRICTMPTR="true"/> <divrule DIVID="ID1.1.1" RESTRICTMPTR="true"> <filetype FILEGROUPID="FILE1"/> </divrule> <divrule DIVID="ID1.1.2" RESTRICTMPTR="true"/> </metsconstraint>

  16. Ingestion Workflow • Negotiate Submission Agreement. • Workflow Initialization and Submission Information Packet creation. • Transfer of SIPs to archive. • Validation of SIP transfer • Organization of data into collections and transfer into persistent archive.

  17. Initialize Ingestion workflow • Instantiate Producer management server to track registered objects • Establish a working trust relationship with the Archive • Issue clients.

  18. Create SIP • Each client registers objects stored locally with producer management server • Register file types, validation tests, etc • Client follows rules in Submission Agreement • Producer-wide agents can arrange registered object to give a broader context

  19. METS Handles all areas of a SIP except Physical Object and Descriptive Information Descriptive Information can be embedded into METS as 3rd party XML schema SIP Example

  20. Mapping SIP metadata to METS • Packaging Information • SIP only exists in entirety during transit • METS Flocat sections allow mapping of metadata to physical object at various stages in transit. • Content Information • Physical Object – encoded in http/tar stream • Representation Information – point to validation services at an archive rather than viewer. Tests are assumed to be representative of viewers

  21. Mapping SIP metadata to METS (cont) • Preservation Description Information • Provenance – stacked File location tags • Context – provided by structural map section • Reference – can be embedded in various descriptive metadata sections (Dublin Core, etc) • Fixity – Provided by checksums in each file.

  22. Client Interface

  23. Ingestion Workflow • Negotiate Submission Agreement. • Workflow Initialization and Submission Information Packet creation. • Transfer of SIPs to archive. • Validation of SIP transfer • Organization of data into collections and transfer into persistent archive.

  24. Transfer SIP to archive • Retrieve previously registered SIP from producer management server • Authenticate to archive • Update provenance information in METS document with file structure of SIP • Transfer METS document describing SIP and container for SIP physical objects • Archive acknowledges transfer completion to producer management server

  25. Ingestion Workflow • Negotiate Submission Agreement. • Workflow Initialization and Submission Information Packet creation. • Transfer of SIP to archive. • Validation of SIP transfer • Organization of data into collections and transfer into persistent archive.

  26. Validation of SIP transfer • Check incoming SIP against constraints documents. • Ensure object integrity by verifying checksums/cryptographic digest • Validate bitstreams against tests described in METS document • Update METS document with validation results and movement of objects on receiving server

  27. Ingestion Workflow • Negotiate Submission Agreement. • Workflow Initialization and Submission Information Packet creation. • Transfer of SIP to archive. • Validation of SIP transfer • Organization of data into collections and transfer into persistent archive.

  28. Final transfer to archive • Transfer objects to digital archive • Update provenance information in METS document with handle to object in archive • Transfer METS document into archive • Return accept/reject messages to producer metadata server

  29. Component Overview

  30. Producer Components • Database to track registered objects • Certificate Authority management • Web service for archive security check • Management server supplies web service interfaces to ingestion clients and management operations. • Clients are designed to be standalone, with security certificates issued by producer

  31. Archive Components • Receiving servers validate connecting clients and validate SIPs • Validation Services are simple webservice calls. • Abstract I/O layer into digital archive.

  32. Recap • Implemented using web technologies • Architecture independent • OAIS compliant • XML based metadata • METS based SIPs • Add-on constraints describing Submission Agreement

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