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 &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>

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