principles from the past projects on
˲ • Any unit of information represented in digital form may be structured
as a digital object (DO) for access (with
suitable controls) within the Internet.
DOs may include digitized versions of
text files, sounds, images, contracts and
photos, as well as information embedded in RFID devices, chip designs, simulations, or genome codes. The structure of a DO, including its metadata, is
machine and platform independent.
˲ • Every DO has a unique persistent
identifier, called a “handle,” or generically, a “digital object identifier,” that
can distinguish a DO (or separately
identified parts of it) from every other
object, present, past, or future. Handles consist of a unique prefix allotted
to an entity (such as a publisher or individual) followed by a string of symbols
chosen by the entity. The “resolution”
system maps handles to state information that includes location, authentication, rights specifications, allowed operations, and object attributes.
˲ • DOs can be stored in DO Repositories, which are searchable systems that
offer continuous access to objects over
long time intervals that span technology generations.
˲ • Accesses to an instance of DO Repository are made via a standard DO
protocol that restricts actions to those
consistent with an object’s state information.
The primary components of CNRI’s
DOA design are the Handle System, DO
Repositories, and DO Registries:
˲ • The Handle System allots prefixes
to registered administrators of local
handle services and provides resolution services for their digital object
identifiers. This system has been available as a service on the Internet since
the middle 1990s and is highly reliable.
It makes use of existing Internet protocols, which do not need redesign. Handle services also support domain name
resolution for backward compatibility.
˲ • The DO repositories use standard
storage systems. They provide digital
object management services with a
standard protocol called digital object
protocol (DOP). The DO repositories
also support HTTP and DOP-over-TLS,
a secure socket layer (SSL) service.
˲ • The DO registries allow users to
reference, federate, and otherwise
The Web was an
but it is far from
manage collections across multiple
repositories and allow for protected
access to such information including
completely private information, sharing within designated groups, and full
Examples of Doa in use
The figure on the first page of this column shows the essence of a resolution
of a DOI to a URL or a file name, using
the ACM Digital Library as an example.
The International DOI Foundation
(IDF) is a non-profit organization that
administers DOIs for a variety of organizations, mostly publishers. The
IDF has trademarked the DOI; and it
uses the Handle System technology for
resolution. One of the IDF Registration
Agents (RAs), DataCite, manages large
scientific data sets using DOIs. The
largest of the IDF RAs, CrossRef, manages metadata on behalf of a large segment of the publishing industry.
The U.S. Library of Congress uses
the Handle System to identify large
parts of its collections. The U.S. Department of Defense ( http://www.adlnet.
gov) relies on the Handle System and
DOI Registry and Repository to manage distributed learning material. The
European Persistent Identifier Consortium (EPIC) (
http://www.pidconsor-tium.eu) provides identifier services
to the European research community.
People in the legal community are implementing the DOA for wills, deeds to
real property, bills of lading, and other
The quest for universal information
access in networks began around
1960 and over the years yielded a set
of principles to fully support universal
information access. These principles
include unique, persistent identifi-
ers, protocols that map identifiers to
objects (including their metadata),
protocols for enforcing access and
use rights, and repositories that hold
objects for indefinite periods span-
ning technology generations. These
principles offer a possible solution to
universal information access and an
infrastructure for more general infor-
1. Corporation for national research initiatives. A Brief
Overview of the Digital Object Architecture and its
Application to Identification, Discovery, Resolution and
Access to Information in Digital Form (june 2010);
2. dennis, j.b.and Van horn, e. programming semantics
for multiprogrammed computations. Commun. ACM 9,
3 (mar. 1966), 143–155.
3. graham, g.S. and denning, p. protection: principles
and practice. AFIPS SJCC Conference (may 1972),
417–429. doi: 10.1145/1478873.1478928.
4. Kahn, r.e. and lyons, p. representing value as digital
objects: a discussion of transferability and anonymity.
Journal of Telecommunications and High Technology
Law 5 (2006).
5. Kahn, r.e. and Wilensky, r. a framework for
distributed digital object services. International
Journal on Digital Libraries 6, 2 (2006). doi: 10.1007/
s00799-005-0128-x. (First made available on the
internet in 1995 and reprinted in 2006 as part of a
collection of seminal papers on digital libraries).
Peter J. Denning ( firstname.lastname@example.org) is distinguished
professor of Computer Science and director of the
Cebrowski institute for innovation and information
Superiority at the naval postgraduate School in monterey,
Ca and is a past president of aCm.
Robert E. Kahn ( email@example.com) is president
and Ceo of the Corporation for national research
initiatives and a recipient of the aCm a.m.turing award.