The paper highlights the specific problems raised by distributed systems programming and also the way in which these particularities have influenced the definition of new programming languages, specially dedicated for...
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ISBN:
(纸本)9789889867140
The paper highlights the specific problems raised by distributed systems programming and also the way in which these particularities have influenced the definition of new programming languages, specially dedicated for this type of programming. For this purpose the concepts introduced in a number of approximately 20 programming languages are analyzed, together with the evolution of these concepts from the first languages based on communication through message transmission (CSP, DP or Ada) to the object oriented languages or their distributed extensions (Concurrent C++, Concurrent Smalltalk or Java). In the final part, based on these ideas, a new programming language is defined, which is currently being implemented in the programming languages laboratory of "Politehnica" University of Timisoara, Romania.
Usually, there are two alternative approaches to program the application functions to be performed by a hard real-time system: the method of sequential programming of tasks often performed under control of a multi-tas...
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Usually, there are two alternative approaches to program the application functions to be performed by a hard real-time system: the method of sequential programming of tasks often performed under control of a multi-tas...
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Usually, there are two alternative approaches to program the application functions to be performed by a hard real-time system: the method of sequential programming of tasks often performed under control of a multi-tasking operating system and, on the other hand, the quasi-parallel description of application functions which are realized by means of a cyclic execution e.g. of a programmable logic control. Although being alternatives in a wide area of applications, there are always aspects of each form of programming where the solution for a specific problem is not really satisfying. Therefore we tried to make use of a combined programming of real-time applications by means of both methods which showed to offer an optimal programming toolset. This paper presents specific characteristics of the two methods, aspects of the combination and examples coming from a new robot programming language which is designed this way.
A special feature of the occam programming language is that its concurrency support is at the very base of the language. However, its ability to specify scheduling requirements is insufficient for use in some real-tim...
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ISBN:
(纸本)9781586039073
A special feature of the occam programming language is that its concurrency support is at the very base of the language. However, its ability to specify scheduling requirements is insufficient for use in some real-time systems. Toc is an experimental programming language that builds oil occam, keeping occam's concurrency mechanisms, while fundamentally changing its concept of time. In Toc, deadlines are specified directly in code, replacing occam's priority constructs as the method for controlling scheduling. Processes are scheduled lazily, in that code is not executed without an associated deadline. The deadlines propagate through channel communications, which means that a task blocked by a channel that is not ready will transfer its deadline through the channel to the dependent task. This allows the deadlines of dependent tasks to be inferred, and also creates a scheduling effect similar to priority inheritance. A compiler and run-time system has been implemented to demonstrate these principles.
Sophisticated Cardiac Monitoring sets an ideally suited field for a device built around microprocessors. Elaboration of such a device, intended for ECG-gating of scintigraphic images, is briefly discussed. During the ...
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Recent technological advances in communication systems now allow the exploitation of real-time information for dynamic vehicle routing and scheduling. It is possible, in particular, to consider diverting a vehicle awa...
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Recent technological advances in communication systems now allow the exploitation of real-time information for dynamic vehicle routing and scheduling. It is possible, in particular, to consider diverting a vehicle away from its current destination in response to a new customer request. In this paper, a strategy for assigning customer requests, which includes diversion, is proposed, and various issues related to it are presented. An empirical evaluation of the proposed approach is performed within a previously reported tabu search heuristic. Simulations compare the tabu search heuristic, with and without the new strategy, on a dynamic problem motivated from a courier service application. The results demonstrate the potential savings that can be obtained through the application of the proposed approach.
This paper studies task allocation in computational grids operating in a dynamic and uncertain environment. Computational grids consist of loosely coupled heterogeneous resources or agents with finite buffer capacitie...
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This paper studies task allocation in computational grids operating in a dynamic and uncertain environment. Computational grids consist of loosely coupled heterogeneous resources or agents with finite buffer capacities. These grids are primarily used to process large-scale applications consisting of several interdependent tasks. The task allocation problem is modeled as an infinite horizon Markov decision process, with the resource service times and the task arrivals following general probability distributions. We explicitly consider the communication cost between agents incurred in coordinating the execution of interdependent tasks. We show that a stationary optimal policy exists for this task allocation problem. Furthermore, we develop an action elimination procedure for reducing the complexity of computational methods in finding the optimal policy. We also present a real-time heuristic policy based on certain structural properties of the problem. Finally, computational results are presented that compare the performance of the heuristic policy with respect to other approaches for allocating tasks in the grid. Results from this paper are also applicable to the task allocation problem in manufacturing and service areas such as distributed design, project management and supplier coalitions.
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