Digital Objects, Identifiers and the recently published Digital Object Interface Protocol (DOIP)

Author: René van Horik (DANS)

Dr. Robert Kahn, the inventor of the TCP/IP protocol and one of the internet pioneers, gave a keynote at a workshop on Digital Objects organized by the “Group of European Data Experts in RDA[1]” late September.

His presentation concerned the Digital Object Architecture (DOA) in which identifiers undeniably play an important role. As the TCP/IP protocol describes the exchange of meaningless messages between devices with an IP address the need to exchange meaningful Digital Objects[2] became apparent early on and for which a DO Architecture (DOA) is required. Each DO has, as an essential element of this architecture, an associated unique persistent identifier, referred to informally as a handle.

Kahn stated that the DOA may be viewed as a logical extension of the internet architecture that addresses the need to support information management more generally than just conveying information in digital form from one location in the Internet to another. The most important characteristics of the DOA concern its open architecture with defined protocols and interfaces, its independence from the underlying technology and its minimized complexity for users. It is a non-proprietary architecture and is publicly available without charge.

Kahn announced the second version of the Digital Object Interface Protocol (DOIP) that enables the interoperability between DOs[3]. The DOIP enables a user (or another DO) to interact with a DO based on the use of associated identifiers. The neutral and international DONA Foundation founded in 2004, plays in important role in the implementation and governance of the DOA. As part of this task it oversees the administration of the Global Handle Registry, the basis for a several identifier services such as the DOI.

Kahn expressed his conviction that the concept of DO can enable a new wave of interoperability between the many different information systems in the world. For this it is essential that DOIP, just as the TCP/IP protocol, are crucial pieces of technology that should be free, non-proprietary and open available.

[1] <>

[2] A Digital Object (DO) is defined as “a sequence of bits, or a set of sequences of bits, incorporating a work or portion of a work or other information in which a party has rights or interests, or in which there is value, each of sequences being structured in a way that is interpretable by one or more computational facilities” (DOIP protocol specification, version 2.0, November 12, 2018 p.1 <>)

[3] <>