Report Number: CS-TR-97-1581
Institution: Stanford University, Department of Computer Science
Title: Towards Interoperability in Digital Libraries: Overview and Selected Highlights of the Stanford Digital Library Project
Author: Paepcke, Andreas
Author: Cousins, Steve B.
Author: Garcia-Molina, Hector
Author: Hassan, Scott W.
Author: Ketchpel, Steven K.
Author: Roscheisen, Martin
Author: Winograd, Terry
Date: January 1997
Abstract: We outline the scope of the Stanford Digital Library Project which covers five areas: user interface work, technologies for locating information and library services, the emerging economic perspective of digital libraries, infrastructure technology and the use of agent technologies to support all of these aspects. We describe technical details for two specific efforts that have been realized in prototype implementions. First, we describe how we employ distributed object technology to move towards an implementation of our InfoBus vision. The InfoBus consists of translation services and wrappers around existing protocols to cope with the problem of interoperability and the distributed nature of emerging digital library services. We model autonomous, heterogeneous library services as CORBA proxy objects. This allows the construction of unified but extensible method-based interfaces for client programs to interact through. We describe how distributed objects enable the design of communication protocols that leave implementors a large degree of freedom. This is a benefit because the resulting implementations can allow users to choose among multiple performance profile tradeoffs while staying within the confines of the protocol. The second effort we cover describes InterPay which uses the object approach for an architecture that helps manage heterogeneity in payment mechanisms among autonomous services. The architecture is organized into three layers. The top layer contains elements involved in the task-level interaction with the services. The middle layer is responsible for enforcing user-specified payment policies. The lowest layer manages the mechanics of diverse online payment schemes.