What would be the ideal attributes of a client-server authentication scheme? One might like an identity based scheme not requiring PKI, plus support for multi-factor authentication based on a token, a PIN number, and optionally a biometric. The former might hold a high-entropy secret, and the latter may be represented as relatively lowentropy parameters. However it would be preferred if the tok...

Last few years have seen exponential growth in the area of web applications, especially, e-commerce and web services. One of the most important QoS metric for web applications is the response time for the user. Web application normally has a multi-tier architecture and a request might have to traverse through all the tiers before finishing its processing. Therefore, a request’s total response t...

VRML97 allows the description of dynamic worlds that can change with both the passage of time, and user interaction. Unfortunately, the current VRML usage model prevents its full potential from being realized. Initially, the whole world must be loaded into the user’s desktop browser, and so large worlds can take a very long time to download and render, while a world cannot be shared among multi...

Distributed threats like botnets are among the most serious threats in the Internet. Due to their distributed nature, these attacks are difficult to detect in an early stage without the collaboration of several network operators. However, the exchange of monitoring data between different parties turns out to be difficult in practice, due to the desire of operators not to disclose network intern...

Operating systems for PCs and workstations adopt finetuned monolithic configuration. On the other hand, microkernel based multi-server operating systems are expected to play important roles especially for real-time and embedded systems, for several reasons. Operating systems for real-time systems are not yet standardized. Requirements to these OS depends on their wide-ranged applications. There...

Traditional password based authentication schemes are mostly considered in single server environments. They are unfitted for the multi-server environments from two aspects. On the one hand, users need to register in each server and to store large sets of data, including identities and passwords. On the other hand, servers are required to store a verification table containing user identities and...

In this paper we analyse a multi-server queueing model with locking. The model is motivated by a situation we encountered at a maintenance facility for trains. Maintenance is done at parallel tracks, where each track ooers space to two trains. Trains can enter and leave the tracks from one and the same side only. This gives rise to locking of the front train: in order to leave the maintenance t...

We consider a slotted queueing system with C servers (processors) that can handle tasks (jobs). Tasks arrive in batches of random size at the start of every slot. Any task can be executed by any server in one slot with success probability α. If a task execution fails, then the task must be handled in some later time slot until it has been completed successfully. Tasks may be processed by severa...

In an online dial-a-ride problem, a crew of servers has to process transportation requests as they arrive in real time. Possible objective functions include minimizing the makespan and minimizing the sum of completion times. We give competitive algorithms and negative results for several online dial-a-ride problems with multiple servers. Surprisingly, in some cases the competitive ratio is dram...

A time server system has been constructed at the University of Newcastle upon Tyne which may be accessed by users of the campus Ethernet. It uses a commercially available radio clock to receive an accurate time signal from the MSF transmitter at Rugby, and can respond to requests from users of the network using a number of different protocols. This paper describes the server system, both hardwa...