Week 2: Notes from Works About Interoperability, Extensibility, and the World Wide Web

In addition to establishing an accepted definition for digital libraries, there is a movement within the field to establish a protocol or set of standards for building the components of digital libraries.

Having a standard protocol for digital library development allows for both interoperability (the ability to use the same components with the same functionality across different interfaces) and extensibility (allowing for future development of the components without compromising functionality).  In order to develop a protocol, one must define and standardize the components of digital libraries.

Some of the components defined in these articles are:

• repositories where digital objects are stored 
  
• handles or identifiers for digital objects
• disseminators or processes associated with digital objects that provide increased functionality
• servlets or programs containing a collection of operations and associated with a specific disseminator types

Interoperability and extensibility allow developments and information to flow across multiple sources (as information flows across servers in the World Wide Web) and allows them to be dynamic and open to improving functionality as technology improves.  An established set of protocols for building components of digital libraries would allow those components to become mobile and would allow creators of digital libraries to customize a set of tools already established (instead of re-creating the wheel with each new library).  This is not a new concept - programming languages (such as java) use an established set of tools to build and customize sophisticated programs which can be used across many interfaces.

The Digital Library Research Group at Cornell University and the Corporation for National Research Initiatives (CNRI) have been working together to establish infrastructures that provide real-life examples of interoperability and extensibility through open architecture.     They tested the interoperability of their product across repositories, disseminators, and the behaviors of their digital objects.

Their tests show that:

• Interoperability across repositories can be established using RAP (Repository Access Protocol)  interface
• The same tasks can be accomplished in separate repositories with the same outcome
• Extensibility can be established, which allows community standards to be integrated into existing digital libraries

Future work of the Cornell/CNRI group will focus on:

• Allowing more variation between repositories without compromising interoperability
  
• Creating a measurement system for interoperability
  
• More testing for interoperability
• Issues of security

William Arms discusses the history and components of the World Wide Web in his chapter, "Overview of the World Wide Web".   This chapter applies to the development of digital libraries because the web can serve as an example of a well-established network of information with both  interoperability and extensibility.  Like the architectural concepts of digital libraries described by Arms et al., the World Wide Web is supported by a set of well-defined components which are functional across systems and allow information to flow freely across networks.  Arms would argue that the world wide web is under-credited (because of it's perceived exclusion from the library world) as being significant to digital library development.


References:
1.Hussein Suleman and Edward A. Fox. “A Framework for Building Open Digital Libraries”, D-Lib Magazine, December 2001. Volume 7 Number 12. http://www.dlib.org/dlib/december01/suleman/12suleman.html.
2.William Y. Arms , Christophe Blanchi, Edward A. Overly. ”An Architecture for Information in Digital Libraries”. D-Lib Magazine, February 1997. http://www.dlib.org/dlib/february97/cnri/02arms1.html.
3.Sandra Payette, Christophe Blanchi, Carl Lagoze, Edward A. Overly. “Interoperability for Digital Objects and Repositories, The Cornell/CNRI Experiments”, D-Lib Magazine, May 1999, Volume 5 Issue 5. http://www.dlib.org/dlib/may99/payette/05payette.html.
4.ARMS, Chapter 2, or “An Overview of World Wide Web”, http://www.cio.com/WebMaster/sem2_home.html