A Tutorial Introduction to Mosaic Pascal

In this report we describe a Pascal system that has been developed for programming Mosaic multi- computers. The system that we discuss runs on our Sun workstations, and we assume some familiarity with the use thereof. We assume the reader to be also familiar with programming in Pascal, and with message-passing programs. We describe how the Pascal language has been extended to perform message passing. We discuss a few implementation aspects that are relevant only to those users who have a need (or desire) to control some machine-specific aspects. The latter requires some detailed knowledge of the Mosaic system

Weakest Preconditions for Progress

Predicate transformers that map the postcondition and all intermediate conditions of a command to a precondition are introduced. They can be used to specify certain progress properties of sequential programs

Improved eventing protocol for universal plug and play

UPnP is a widely-spread connectivity standard, which allows networked devices to cooperate in an autonomous fashion by using functionality found on the network. In this article we validate UPnP as a service-oriented architecture. We identify shortcomings of the standard and propose solutions. In our view, eventing is the weakest mechanism in UPnP technology. We propose extensions to the existing eventing protocol in UPnP, which allow overcoming identified problems. We compare our solution with standard UPnP with respect to performance

Infinitely-fast diffusion in Single-File Systems

We have used Dynamic Monte Carlo (DMC) methods and analytical techniques to analyze Single-File Systems for which diffusion is infinitely-fast. We have simplified the Master Equation removing the fast reactions and we have introduced a DMC algorithm for infinitely-fast diffusion. The DMC method for fast diffusion give similar results as the standard DMC with high diffusion rates. We have investigated the influence of characteristic parameters, such as pipe length, adsorption, desorption and conversion rate constants on the steady-state properties of Single-File Systems with a reaction, looking at cases when all the sites are reactive and when only some of them are reactive. We find that the effect of fast diffusion on single-file properties of the system is absent even when diffusion is infinitely-fast. Diffusion is not important in these systems. Smaller systems are less reactive and the occupancy profiles for infinitely-long systems show an exponential behavior.Comment: 8 pages, 5 figure

A first step towards a dependability framework for smart environment applications

Smart environments will consist of a large number of heterogeneous devices that communicate to collaboratively perform various tasks for users. We propose a novel dependability framework to increase availability and reliability of smart environment applications. We argue that the key step in achieving high dependability is to predict faults before they occur. Many statistical fault prediction techniques have been proposed for smart environment applications. Selecting the best one among these techniques involves performance assessment and detailed comparison on given metrics. We present a linear regression-based prediction model to predict the remaining battery lifetime of a device to prevent faults due to low battery. Further, we discuss the proposed dependability framework, the basic approaches and the corresponding mechanisms to achieve our long-term research goal. We envision that dependability framework will reduce maintenance costs of large-scale smart environments and increase the dependability of smart environment applications

Worst-case response time analysis of real-time tasks under fixed-priority scheduling with deferred preemption revisited

Fixed-priority scheduling with deferred preemption (FPDS) has been proposed in the literature as a viable alternative to fixed-priority preemptive scheduling (FPPS), that both reduces the cost of arbitrary preemptions and removes the need for non-trivial resource access protocols. This paper shows that existing worst-case response time analysis of hard real-time tasks under FPDS, arbitrary phasing and relative deadlines at most equal to periods is both pessimistic and optimistic. This paper provides a revised analysis, resolving the problems with the existing approaches. The analysis assumes a continuous scheduling model. It is shown that the critical instant, longest busy period, and worst-case response time for a task are suprema rather than maxima for all tasks, except for the lowest priority task. Moreover, it is shown that the analysis is not uniform for all tasks, i.e. the analysis for the lowest priority task differs from the analysis of the other tasks, because only the lowest priority task cannot be blocked. To build on earlier work, the worst-case response time analysis for FPDS is expressed in terms of known worst-case analysis results for FPPS. The paper includes pessimistic variants of the analysis, which are uniform for all tasks

Performance and fairness in VANETs

This paper presents performance and fairness analysis of the 802.11p Medium Access Control (MAC) in one-hop periodic broadcast V2V communication used in cooperative driving applications aimed for improving vehicle safety and traffic efficiency. We show that both performance and fairness strongly dependent on the random relative phasing (F0) of the vehicles and on the impact of Hidden Nodes (HNs)

Grasp : visualizing the behavior of hierarchical multiprocessor real-time systems

Trace visualization is a viable approach for gaining insight into the behavior of complex distributed real-time systems. Grasp is a versatile trace visualization toolset. This paper presents its unique visualization capabilities for hierarchical multiprocessor systems, including partitioned and global multiprocessor scheduling with migrating tasks and jobs, communication between jobs via shared memory and message passing, and hierarchical scheduling in combination with multiprocessor scheduling. Its flexible plugin infrastructure allows for easy extension with custom visualization and analysis techniques for automatic trace verification. Grasp is freely available on the web