ESA's highly mobile "road warriors" require ubiquitous and secure connectivity to ESA premises and information from any civilized location, but also reaching out to the equatorial jungles and to the Asian steppes. ESA mobility pack services have been developed to allow such connectivity in scenarios ranging from those where Internet access is provided directly by the host organization, to those where the only available connection is a telephone line (wired or wireless).

Network computing is an emerging paradigm that promises to extend computing and information access capabilities transparently beyond the domain of a specific organization and enable unprecedented collaboration and business transactions in a global open network environment. It also challenges the present client-server paradigm, which has proven to be rather expensive, owing to the high cost of maintaining and managing individual workstations and PCs. Network computing is closely coupled with the Internet and World Wide Web explosion. The HTTP-based browser is becoming a standard open universal interface not just for WWW browsing, but for access to corporate databases, for remote system/network management, communication and collaboration, workflow management, and for other services and applications. The Network Computer (NC) is viewed by many as the successor of the familiar PC, that will get most of the needed software and services on demand from the network. To realize the vision of network computing, powerful, robust, and efficient “backend” infrastructure is required to provide such applications and services within an organization, across domains, and on the global scale. What kind of role does the autonomous distributed system (ADS) paradigm play in network computing? Are these two different worlds? Are they complementary? Or, is ADS an inseparable part of or a base for the fledging network computing? The individual panelists address these questions from the point of view of different environments and applications. They discuss technologies that support these paradigms and form a bridge between them.

The authors discuss the upper and lower bounds on the accuracy of the time synchronization achieved by the algorithm implemented in TEMPO, the distributed service that synchronizes the clocks of the University of California, Berkeley, UNIX 4.3BSD systems. The accuracy is shown to be a function of the network transmission latency; it depends linearly upon the drift rate of the clocks and the interval between synchronizations. TEMPO keeps the clocks of the VAX computers in a local area network synchronized with an accuracy comparable to the resolution of single-machine clocks. Comparison with other clock synchronization algorithms shows that TEMPO, in an environment with no Byzantine faults, can achieve better synchronization at a lower cost.>