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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 - PowerPoint PPT Presentation
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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 Use of web/grid technologies – platform
independent Minimal client-side requirements Ease of integration with archival storage or
data grid systems.
Producer
Producer Management Interface
Producer data suppliers
Archive
Management Server
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.
Archive - receiving
Bitstream Validation Service
Digital Archive
Scheduler
Producer 1
Producer n
Producer 2
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.
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
Ingestion Workflow
1. Negotiate Submission Agreement.
2. Workflow Initialization and Submission Information Packet (SIP) creation.
3. Transfer of SIPs to archive.
4. Validation of SIP transfer
5. Organization of data into collections and transfer into persistent archive.
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
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/
Sample METS Document<?xml version="1.0" encoding="utf-8" standalone="no"?><mets xmlns="http://www.loc.gov/METS/" xmlns:xlink="http://www.w3.org/TR/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/METS/ http://www.loc.gov/standards/mets/mets.xsd"><metsHdr><agent ROLE="CREATOR"><name>toaster@hostname</name>
</agent></metsHdr><fileSec><fileGrp><file ID="5" MIMETYPE="application/octet-stream" SIZE="67624" CREATED="2002-08-21T15:36:05"
CHECKSUM="2CE7D79E40BD6C6A65A6684B6FD3D08C" CHECKSUMTYPE="MD5"><FLocat LOCTYPE="URL" xlink:type="simple" xlink:href="/nfshomes/toaster/iscsi/GFS-contrib-5.1.tar.gz"/>
</file></fileGrp><fileGrp><file ID="7" MIMETYPE="application/octet-stream" SIZE="2517" CREATED="2002-09-06T17:06:07"
CHECKSUM="767185AA022180E701324C592E1C36E3" CHECKSUMTYPE="MD5"><FLocat LOCTYPE="URL" xlink:type="simple" xlink:href="/nfshomes/toaster/iscsi/gfs.out"/>
</file></fileGrp>
</fileSec><structMap><div ID="3" LABEL="iscsi"><fptr FILEID="5"/><fptr FILEID="7"/>
</div></structMap>
</mets>
MetadataLinking
StructuralOrganization
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
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.
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 & Development Records"><div ID="ID1.1" LABEL="Research & Development Project Records">
<div ID="ID1.1.1" LABEL="R&D Project Case Files"/><div ID="ID1.1.2" LABEL="R&D Record Series"/>
</div></div>
</structMap></mets>
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>
Ingestion Workflow
1. Negotiate Submission Agreement.
2. Workflow Initialization and Submission Information Packet creation.
3. Transfer of SIPs to archive.
4. Validation of SIP transfer
5. Organization of data into collections and transfer into persistent archive.
Initialize Ingestion workflow
Instantiate Producer management server to track registered objects
Establish a working trust relationship with the Archive
Issue clients.
Create SIP
Each client registers objects stored locally with producer management serverRegister file types, validation tests, etcClient follows rules in Submission Agreement
Producer-wide agents can arrange registered object to give a broader context
SIP Example
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
· Physical Object· Representation
Information
· Provenance· Fixity· Reference · Context
Packaging Information
Descriptive Information
Content InformationPreservation Description
Information
OAIS Information packet
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
Mapping SIP metadata to METS (cont) Preservation Description Information
Provenance – stacked File location tagsContext – provided by structural map sectionReference – can be embedded in various
descriptive metadata sections (Dublin Core, etc)
Fixity – Provided by checksums in each file.
Client Interface
Ingestion Workflow
1. Negotiate Submission Agreement.
2. Workflow Initialization and Submission Information Packet creation.
3. Transfer of SIPs to archive.
4. Validation of SIP transfer
5. Organization of data into collections and transfer into persistent archive.
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
Ingestion Workflow
1. Negotiate Submission Agreement.
2. Workflow Initialization and Submission Information Packet creation.
3. Transfer of SIP to archive.
4. Validation of SIP transfer
5. Organization of data into collections and transfer into persistent archive.
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
Ingestion Workflow
1. Negotiate Submission Agreement.
2. Workflow Initialization and Submission Information Packet creation.
3. Transfer of SIP to archive.
4. Validation of SIP transfer
5. Organization of data into collections and transfer into persistent archive.
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
Component Overview
CRL check
Success/Failure notification of ingestion
METS document registration/retrieval
Producer Management Interface Archive Management Interface
Producer data suppliersBitstream Validation Service
Archive Data Grid
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
Archive Components
Receiving servers validate connecting clients and validate SIPs
Validation Services are simple webservice calls.
Abstract I/O layer into digital archive.
Recap
Implemented using web technologies Architecture independent OAIS compliant XML based metadata
METS based SIPsAdd-on constraints describing Submission
Agreement