206837704
Synchronous flow control in wormhole routed optical networks
In this paper, we propose a synchronous flow control mechanism in wormhole routed optical networks. It is expected that the benefit of shorter routing delay and smaller buffer size requirement in wormhole routing will be significant in optical networks. Different from the traditional bi-directional asynchronous back-pressure flow control, the flow control is modified to be unidirectional and synchronous. The size of synchronized control slot does not depend on the routing path length and the number of bits is a constant which is equal to the total number of virtual channels and nodes. The proposed flow control takes advantage of the restricted order of accessing channels in deadlock-free routing to broadcast their control information in a corresponding restricted order. Furthermore, in order to reduce the buffer size to only one unit, the virtual channels which share the same physical channel must be able to simultaneously transmit data. The low channel utilization induced by such mechanism is overcome by our modified source routing. In summary, this paper introduces a flow control mechanism which easily incorporates the benefit of wormhole routing into the limited-resource optical networks.
14017324
A checkpointing tool for Palm operating system
It is foreseeable that handheld devices will be involved in the arena of distributed computing in the near future. To provide a dependable computing environment, check-pointing and rollback recovery is a useful and important technique for fault-tolerant distributed computing systems. For the most popular platform among handhelds, Palm OS, its built-in HotSync tool can take a partial snapshot of a system state, but it synchronizes only the static data in the handheld with a PC. All dynamic data of applications are lost if a failure occurs and the Palm OS is reset. In order to accommodate mobile computing devices with checkpointing and rollback recovery capability, dynamic data such as global variables should be checkpointed to tolerate system reset/crash failure. Therefore, we developed a checkpointing tool, which provides a set of APIs to checkpoint Palm applications. Using the checkpointing tool, dynamic data in a Palm device can be saved and recovered from a system reset. We describe the tool and demonstrate its usefulness in four popular Palm applications.
30164245
Reliable Multicast based on k-Connected Graph
96190
Optimal resource allocation and reliability analysis for component-based software applications
In this paper we propose an analytical approach for estimating the reliability of a component-based software. This methodology assumes that the software components are heterogeneous and the transfers of control between components follow a discrete time Markov process. Besides, we also formulate and. solve two resource allocation problems. Finally, we demonstrate how these analytical approaches can be employed to measure the reliability of a software system including multiple-input/multiple-output systems and distributed software systems. Experimental results show that the proposed methods can solve the testing-effort allocation problems and improve the quality and reliability of a software system.
25953242
Restoration from Multiple Faults in WDM Networks without Wavelength Conversion
This paper addresses the problem of achieving full and fast restoration to tolerate as many faults as possible in wavelength-routed wavelength division multiplexing (WDM) networks with no wavelength conversion. We model the problem of finding the maximum number of faults tolerated as a constrained ring cover problem, which is a decomposition problem of exponential complexity. Three heuristic methods which guarantee that at least one fault can be tolerated are proposed. The Ear Decomposition (ED) method can always generate a decomposition to guarantee that only one fault can be tolerated. The Planar Decomposition (PD) method, which takes advantage of the bipartite graph model to generate a decomposition, can tolerate up to f faults, where f is the maximum cardinality between the two bipartite vertex sets. The Maximally Separated Rings (MSR) method uses the greedy method to find a decomposition to tolerate as many faults as possible. The marked-link (ML) method is also proposed to enhance the performance by marking some links, which are originally used for protection, available for normal transmissions. Finally, we also evaluate the number of faults tolerated and the blocking probabilities of these methods in three example networks.
26449771
Resolving error propagation in distributed systems
This paper investigates the problem of error propagation in distributed systems. To resolve this problem, a state preservation scheme is presented to save process states in main memory. Based on the state preservation, the processes suffering from error propagation can be recovered without involving stable storage. The recovery overhead is significantly reduced. In addition, a well-known single-source-all-destination graph algorithm is also utilized to find the optimal recovery points of the processes suffering from error propagation.
13132411
A New Probabilistic Induction Method
Knowledge acquisition by interviewing a domain expert is one of the most problematic aspects of the development of expert systems. As an alternative, methods for inducing concept descriptions from examples have proven useful in eliminating this bottleneck. In this paper, we propose a probabilistic induction method (PIM), which is an improvement of the Chan and Wong method, for detecting relevant patterns implicit in a given data set. PIM uses the technique of residual analysis and several heuristics to effectively detect complex relevant patterns and to avoid the problem of combinatorial explosion. A reasonable trade-off between the induction time and the classification ratio is achieved. Moreover, PIM quickly classifies unknown objects using classification rules converted from the positively relevant patterns detected. Three experiments are conducted to confirm the validity of PIM.