While much information is available over networks for free or supported by advertising, additional information resources will only become available when the intellectual property rights owners can be assured of payment in return for providing their information. Accordingly, robust, secure, scalable commerce mechanisms are needed to control access to and payment for networked multimedia information [19].

Accomplishments

The Information Networking Institute (INI/CMU) NMIS Project team used NetBill, an Internet billing system developed at Carnegie Mellon, to examine mechanisms to provide billing, authentication and security for network delivery of video information by using the INTERNET CNN Newsroom Video Library as a testbed. NetBill functions as a third party intermediary between a merchant and consumer who wish to conduct business. It provides the mechanisms for consumer- merchant pairs to securely transfer goods and perform financial transactions, as well as accounting and access control for digital libraries. NetBill provides for digital signatures, encrypted goods delivery, and pseudonyms to support anonymity. To meet the requirements of flexibility and scalability, and so that independent parties can easily be involved in the commerce transactions, NetBill is being designed as a system of systems which depend on an infrastructure of authentication, certificate management, Internet access , databases, real- time customer service and dispute resolution servers, etc. [27]

Ian Simpson of Carnegie Mellon University developed a taxonomy of service models and delivery methods for multimedia products and services, and explored the issues associated with authentication, security, and billing for each method. Service models included the use of caching intermediaries, multicast delivery, and scheduled versus on-demand delivery. Each of these models imposed unique requirements for security, usage monitoring, and determination of when a billable event has occurred.[25]

Encrypting video information for delivery is a challenge because of the high bit rates involved [9]. Lei Tang developed and prototyped an encryption scheme customized to MPEG-based video information that provided strong protection while operating on substantially less than the full MPEG bit stream [31]. He also outlined a model for handling streaming video in the context of NetBill, which was originally designed to deliver discrete digital objects in an atomic transaction.

Note that because of rapid changes in the technology of streaming video and commercial applications, implementation of these results in the context of NMIS and NetBill was deferred.

Economics of Network Transport for Multimedia Information

Delivery of multimedia information in real time places stringent performance requirements on a network, such as low jitter rates, and minimal dropped packets. Resource reservation, whether through ATM virtual circuits or using RSVP in the Internet is one method for insuring sufficient network capacity to handle a flow with specified quality of service requirements. If sufficient resources are not available, reservations can be declined (calls blocked).

Economists have begun to call for the use of pricing mechanisms to control resource allocation. However, feasible mechanisms for assigning prices have not been available. The use of a pricing mechanism is one way of insuring that those who value the resources highly are most likely to be able to obtain them. Accordingly, we investigated a number of models for analyzing the relationship between the demand for network services, pricing of resource reservation as well as network usage, and optimal levels of capacity. [4]

These results have led to a three stage model for determining optimal capacity investment in the long run, optimal pricing of virtual circuits in the presence of time varying demand, and optimal congestion-based pricing for best-effort traffic. We show that pricing a network service is similar to pricing a tangible product, except that the marginal cost of producing the product is replaced by the opportunity cost of providing the service, which includes both the opportunity cost of reserving and the opportunity cost of using network capacity. This model has given rise to several publications, including Wang, Sirbu and Peha [32], Wang, Sirbu and Peha [33], and Wang, Sirbu and Peha [34], and a forthcoming PhD dissertation by Qiong Wang.

An "Internet Economics Workshop" was held by the MIT Research Program on Communications Policy on March 9 and 10, 1995 at MIT in Cambridge, MA. Much of the workshop's success was due to their efforts in assembling some of the leading thinkers in the Internet Economics field. Notes were compiled and placed on the WWW (http://rpcp.mit.edu/Workshops/cfp.html). More detailed information about the workshop was published in a special issue of the "Journal of Electronic Publishing" by the University of Michigan Press and distributed on the WWW (http://www.press.umich.edu:80/jep/econTOC.html) [17]. Finally, an edited volume of papers from workshop participants has also been published by MIT Press 1997 [18].

Future Directions

The certified delivery/atomicity properties of NetBill which provide high confidence transactions for discrete chunks of information do not map well into billing for streamed content. Further work is needed to demonstrate high confidence delivery of streamed information. The NetBill technology has been licensed in 1997 to CyberCash which will incorporate the concepts in its products.