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Global Digital Format Registry An Update July 2006 Harvard University Library Global Digital Format Registry • “The Global Digital Format Registry (GDFR) will provide sustainable services to collect, review, store, discover, and deliver significant representation information about digital formats.” – Centrally-organized collection and review – Distributed storage, discovery, and delivery via a peer-to-peer network Harvard University Library The GDFR project • Harvard University Library (HUL) funded for 2 years by the Mellon Foundation • Staffing and technical work subcontracted by HUL to OCLC (June 2006) • Project oversight – Steering Committee (SC) for policy oversight – Technical Working Group (TWG) for technical oversight – Active solicitation of the international stakeholder community for review and comment Harvard University Library Deliverables • • • • • Functional requirements Technical specifications Implementation plan (technology platform) Inter-nodal protocol Reference software implementation for nodes – Released under LGPL • Editorial process • Initial population • Succession plan Harvard University Library Schedule • Month 1 Staffing, establish public web site • Months 2-6 Consultation, design, prototyping Public discussion planned for DLF Fall Forum, Boston, November 2006 • Months 7-12 Protocol, node implementation • Months 13-18 Initial population, inter-nodal testing • Months 19-24 Integration testing Harvard University Library What is a format? • “A serialization of an abstract information model” – A set of syntactic and semantic rules for mapping from an information model to a byte stream (and, in most instances, for mapping back) • Encompasses the nominal sense of “file format” as well as a range of conceptual models from the micro to the macro level – IEEE 754 floating point number … File system Harvard University Library GDFR network • Peer-to-peer network communicating over a common protocol • Structured delegation for distribution Vetted for propagation – DNS analogy Root GDFR node • “Root” node • Top-level nodes Data – Distribution classes • Local data • Unvetted data • Vetted data GDFR node propagation GDFR protocol Editorial process Submissions for technical vetting GDFR node GDFR node Harvard University Library Representation Information • • • • • • • • • Identifiers Responsibility Classification Relationships Specifications Signatures Grammar Tools Assessment Harvard University Library Identifiers • Canonical and alias identifiers in a variety of naming systems – – – – Common usage MIME PRONOM PUID LC FDD “TIFF” “image/tiff” “fmt/10” “fdd000022” • Canonical GDFR-defined identifier in the “info” URI scheme Harvard University Library Responsibility • Creator • Owner • Maintenance agency and process • Legal conditions for use Harvard University Library Classification Ontological CLASSES, abstract families, concrete formats, and relationships BYTESTREAM IMAGE STILL RASTER GIF GIF87a GIF89a JPEG ISO 10918-1 JFIF TIFF TIFF 4.0 TIFF 5.0 TIFF 6.0 TIFF/IT TIFF/IT/CT TIFF/IT/CT/P1 is-new-version-of GIF87a is-subtype-of ISO 10918-1 is-new-version-of is-new-version-of is-subtype-of is-subtype-of is-subtype-of TIFF 4.0 TIFF 5.0 TIFF 6.0 TIFF/IT TIFF/IT/CT Harvard University Library Relationships • Subtype ASCII UTF-8 • Version TIFF 6.0 is-version-of TIFF 5.0 has-version • Encapsulation WAVE μ-law can-contain μ-law is-contained-by WAVE • Affinity JPEG SPIFF is-similar-to is-similar-to is-subtype-of has-subtype UTF-8 ASCII TIFF 5.0 TIFF 6.0 SPIFF JPEG Harvard University Library Specifications • Bibliographic citation, including descriptive (e.g. ISBN) and actionable (e.g. (URI) identifiers • IP considerations probably prohibit the free distribution of specification documents Harvard University Library Signatures • External – Generally indicative – File extension(s) • Internal – Generally dispositive – Magic number – Other well-defined internal syntactic structures Harvard University Library Grammar • Formal notation of a format • Typed to permit multiple parallel formulations, e.g. BNF, ABNF, BSDL, DFDL, EAST • May be feasible only for relatively simple formats Harvard University Library Tools • Services, systems, and tools using formats as inputs or outputs • Described in terms of some functional taxonomy, e.g. edit, transform, render Harvard University Library Assessment • Format-specific risk assessment • Typed to permit multiple parallel formulations – LC Sustainability/Quality & Functionality (SQF) – OCLC INFORM – DSTC PANIC – Cornell Virtual Remote Control (VRC) Harvard University Library General development goals • First create a generalized registry framework, then specialize it for the GDFR application – To the extent that this does not effect other goals and schedules • Platform/network transport independent • Full information content of GDFR is expressible in XML form • GDFR network is re-instantiatable from its XML expression Harvard University Library Related Work • PRONOM www.nationalarchives.gov.uk/pronom/ • Representation Information Registry/Repository dev.dcc.ac.uk/twiki/bin/view/Main/DCCRegRepV04 • LC Digital Formats Web www.digitalpreservation.gov/formats/ • NARA GDFR governance investigation Harvard University Library