Many noticeable studies have focussed on scheduling flat transactions in a distributed real-time database system (RTDBS). However, a nested transaction model has been widely adopted in many real-life applications such...
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Many noticeable studies have focussed on scheduling flat transactions in a distributed real-time database system (RTDBS). However, a nested transaction model has been widely adopted in many real-life applications such as Internet stock trading systems and telecommunications. This work concerns efficiently scheduling real-time nested transactions in a distributed RTDBS. A new real-time scheduler called flexible high reward for nested transactions (FHRN) is proposed. FHRN consists of (1) FHRNp1 policy to schedule real-time nested transactions and (2) 2PL HPN to resolve the concurrent data-accessing problem among interleaved nested transactions. Simulation results show that FHRN outperforms these existent real-time schedulers such as random priority (RP), earliest deadline (ED), highest value (HV), hierarchical earliest deadline (HED), and highest reward and urgency (HRU) when an application requires a nested transaction model.
Reliability is one of the most important properties of integrated supervisory and control system (ISCS) in metro. Redundancy technology, a fault tolerant mechanism, can significantly improve ISCS reliability. This pap...
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ISBN:
(纸本)9783037854235
Reliability is one of the most important properties of integrated supervisory and control system (ISCS) in metro. Redundancy technology, a fault tolerant mechanism, can significantly improve ISCS reliability. This paper introduces a redundancy design schema and its implementation in distributed real-time database, which is the kernel part of ISCS, Including upstream and downstream data redundancy processing technology, fault detection and redundancy switch technology. The result shows that this schema is feasible and reasonable.
The conventional lock scheme tends to suffer from a cascade of blockings, while the optimistic concurrency control (OCC) scheme may suffer from wasting resources. To overcome these problems, some researchers have prop...
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The conventional lock scheme tends to suffer from a cascade of blockings, while the optimistic concurrency control (OCC) scheme may suffer from wasting resources. To overcome these problems, some researchers have proposed a combination of OCC and lock in transaction processing. Using this method, Thomasian proposed the hybrid method for conventional distributed transaction processing, and Lam proposed the DOCC-DA protocol for distributedrealtimedatabase system based on forward validation. This paper proposes a new protocol, called Hybrid distributed Optimistic Concurrency Control Embedded in two-Phase Commit, which is based on back validation. The new protocol makes use of access invariance and runtime information which can guarantee a rerun transaction to meet its deadline and abort the fruitless run transactions as early as possible. A series of simulation experiments have been done to investigate the performance of the new protocol. The results show that its performance is consistently better than that of other protocols.
We investigate the performance implications of providing transaction atomicity for firm-deadline real-time applications operating on distributed data. Using a detailed simulation model, the real-time performance of a ...
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We investigate the performance implications of providing transaction atomicity for firm-deadline real-time applications operating on distributed data. Using a detailed simulation model, the real-time performance of a representative set of classical transaction commit protocols is evaluated. The experimental results show that data distribution has a significant influence on real-time performance and that the choice of commit protocol clearly affects the magnitude of this influence. We also propose and evaluate a new commit protocol, PROMPT (Permits Reading Of Modified Prepared-data for timeliness), that is specifically designed for the realtime domain. PROMPT allows transactions to "optimistically" borrow, in a controlled manner, the updated data of transactions currently in their commit phase. This controlled borrowing reduces the data inaccessibility and the priority inversion that is inherent in distributedreal-time commit processing. A simulation-based evaluation shows PROMPT to be highly successful, as compared to the classical commit protocols, in minimizing the number of missed transaction deadlines. in fact, its performance is close to the best on-line performance that could be achieved using the optimistic lending approach. Further, it is easy to implement and incorporate in current database system software. Finally, PROMPT is compared against an alternative priority inheritance-based approach to addressing priority inversion during commit processing. The results indicate that priority inheritance does not provide tangible performance benefits.
The aircraft utilities distributed synthetic simulation platform hereby provide a simulation platform for the investigation of the aircraft electro-mechanical systems, which consists the cockpit environment control su...
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ISBN:
(纸本)7506278413
The aircraft utilities distributed synthetic simulation platform hereby provide a simulation platform for the investigation of the aircraft electro-mechanical systems, which consists the cockpit environment control subsystem, hydraulic power subsystem, power source subsystem, braking subsystem, fuel management subsystem, front wheel steering subsystem and undercarriage control subsystem, etc. The distributed utilities management system (UMS) simulation platform proposed is designed for integrating hardware and software based on multi-processors connected to dual redundant data-bus to demonstrate the utility management system design scheme. distributed simulation platform hardware topology and software framework are established. Optimized management strategies for the utility subsystems involves load balancing strategy for the purpose of high distributed process ability, distributed real-time database management method, reliability, redundancy, fault handling and realization of the demo environment for the visual simulation.
The design of a distributed real-time database based on cloud theory is proposed. A distributed indexing mechanism is researched to achieve more efficient management of industrial data. A real-time transaction schedul...
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ISBN:
(纸本)9781467347082;9781467347075
The design of a distributed real-time database based on cloud theory is proposed. A distributed indexing mechanism is researched to achieve more efficient management of industrial data. A real-time transaction scheduling algorithm in distributed environment is designed to improve transaction processing efficiency. A network dynamic routing and business related load balancing mechanism is researched to deal with modification of system scale and make full use of system resources. These technologies are utilized to implement distributed real-time database for large-scale process industry. Experimental results show that the cloud-based database has better performance and significantly improves data throughput, fault tolerance and scalability.
The aircraft utilities distributed synthetic simulation platform hereby provide a simulation platform for the investigation of the aircraft electro-mechanical systems, which consists the cockpit environment control su...
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The aircraft utilities distributed synthetic simulation platform hereby provide a simulation platform for the investigation of the aircraft electro-mechanical systems, which consists the cockpit environment control subsystem, hydraulic power subsystem, power source subsystem, braking subsystem, fuel management subsystem, front wheel steering subsystem and undercarriage control subsystem, etc. The distributed utilities management system (UMS) simulation platform proposed is designed for integrating hardware and software based on multi-processors connected to dual redundant data-bus to demonstrate the utility management system design scheme. distributed simulation platform hardware topology and software framework are established. Optimized management strategies for the utility subsystems involves load balancing strategy for the purpose of high distributed process ability, distributed real-time database management method, reliability, redundancy, fault handling and realization of the demo environment for the visual simulation.
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