principles from the past projects on information access:

˲ • 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
important step
toward universal
information sharing
but it is far from
perfect.

manage collections across multiple repositories and allow for protected access to such information including completely private information, sharing within designated groups, and full public access.

 

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 legal instruments.

 

Conclusion

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-
mation management.

References

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); http://www.cnri.reston.va.us/papers/digital_object_ architecture_brief_overview.pdf

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 ( [e-mail]) 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 ( [e-mail]) is president and Ceo of the Corporation for national research initiatives and a recipient of the aCm a.m.turing award.