Scalability and fault tolerance are important features of modern applications designed for the distributed, loosely-coupled computer systems. In the paper, two-layer scalable structures for storing data in a distributed RAM of a multicomputer (SD2DS) are introduced. A data unit of SD2DS (a component) is split into a header and a body. The header identifies the body and contains its address in a network. The headers are stored in the first layer of SD2DS, called the component file, while the bodies are stored in the second layer, called the component storage. Both layers are managed independently. Details of the management algorithms are given, along with SD2DS variant suitable for storing plain records of data. The SD2DS is compared to similar distributed structures and frameworks. Comparison considerations together with test results are also given. The results proved superiority of SD2DS over similar structures.
Mobots (mobile robots) remote-controlled by human operators are more and more widely used for watching and guarding. A mobot should not be controlled by an occasional person. A human being has to show specific ability to be a good mobot operator. This ability is individual for each person and can be discovered with the help of an experiment which is time-consuming and expensive. Then the problem arises whether there is a simple and cheap test of this ability or not and, which is more technical, how to find out such a test. The paper addresses this problem. The experimental data are compared with those obtained with the help of two quick and cheap tests and some correlations between them are pointed out.
The main purpose of this research is adaptation of critical paths method [1] to the processes defined in BPEL. The critical path method is the specification based and simulation oriented method. In the paper it is show that under some assumptions the BPEL process may be considered as an embedded system, in which tasks are like services and communication between tasks is like coordination of the services according to the task graph of the system. An example is given where a set of test scenarios is presented.
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