Dynamic software reconfiguration is a useful tool to adapt and maintain software systems. In most approaches, the system has to be stopped while the reconfiguration is in progress. This is not suitable for real-time s...
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ISBN:
(纸本)0769523560
Dynamic software reconfiguration is a useful tool to adapt and maintain software systems. In most approaches, the system has to be stopped while the reconfiguration is in progress. This is not suitable for real-time systems, even on small-embedded systems. Timing constraints must be met even while the system is reconfiguring. Our approach is based on the realtime middleware OSA+. Our main objective is to be able to reconfigure services during run-time, with a predictable and predefined blackout time (the time the systems does not react due to the reconfiguration). Three different approaches concerning the blocking or non-blocking state of a service are presented. These approaches can be used to realize a tradeoff between the reconfiguration time and the blackout time.
To ensure global serializability, traditional distributed database systems implement both concurrency control and transaction commit protocols. In a distributed database systems, a commit protocol guarantees the unifo...
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ISBN:
(纸本)0769523560
To ensure global serializability, traditional distributed database systems implement both concurrency control and transaction commit protocols. In a distributed database systems, a commit protocol guarantees the uniform commitment of distributed transaction execution. In the last decade, several extensions to the transaction model adopted in traditional database systems have been proposed in order to support the functional and performance requirements of emerging advanced applications such as CAD/CAM, large software design projects and object-oriented databases. Nested transaction models have been shown to play an important role in such applications, however, these models are not yet fully studied. In this paper our contributions in the field of real-time nested transactions are two fold: (i) we propose a hierarchical and flat protocols for real-time nested transactions, called 2PC-RT-NT, and (ii) we implement a lock mechanism, called 2LP-NT-HP, to solve the data conflicts problem between nested transactions.
Organic computing is becoming the new vision for the design of complex systems, satisfying human needs for trustworthy systems that behave life-like by adapting autonomously to dynamic changes of the environment, and ...
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ISBN:
(纸本)0769523560
Organic computing is becoming the new vision for the design of complex systems, satisfying human needs for trustworthy systems that behave life-like by adapting autonomously to dynamic changes of the environment, and have self-x properties as postulated for Autonomic computing. Organic computing is a response to the threatening view of being surrounded by interacting and self-organizing systems which may become unmanageable, showing undesired emergent behavior. Major challenges for organic system design arise from the conflicting requirements to have systems that are at the same time robust and adaptive, having sufficient degrees of freedom for showing self-x properties but being open for human intervention and operating with respect to appropriate rules and constraints to prevent the occurrence of undesired emergent behavior.
The widespread use of mobile and wireless computing platforms is leading to a growing interest on dependability issues. Several research studies have been conducted on dependability of mobile environments, but none of...
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ISBN:
(纸本)0769523560
The widespread use of mobile and wireless computing platforms is leading to a growing interest on dependability issues. Several research studies have been conducted on dependability of mobile environments, but none of them attempted to identify system bottlenecks and to quantify dependability measures. This paper proposes a distributed automated infrastructure for monitoring and collecting spontaneous failures of the Bluetooth infrastructure, which is nowadays more and more recognized as an enabler for mobile systems. Information sources for failure data are presented, and preliminary experimental results are discussed.
The growing complexity of today's embedded real-time systems demands new methods and tools in order to manage the problems of design, analysis, integration and validation of complex systems. This paper describes a...
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ISBN:
(纸本)0769523560
The growing complexity of today's embedded real-time systems demands new methods and tools in order to manage the problems of design, analysis, integration and validation of complex systems. This paper describes an object-oriented platform-based design process for real-time embedded systems. The proposed approach promotes a smooth transition from high-level UML specification to implementation, which is composed by hardware and software components. The transition from higher to lower abstraction levels is facilitated by the use of an OO real-time API, whose underlying facilities can be optimized according to the application needs and selected platform. An integrated toolset is used to support the intermediate steps of the design process. In order to illustrate the proposed approach and related toolset the design of an embedded real-time automation system for an "intelligent" wheelchair is presented.
Code generation from hybrid system models is a promising approach to producing reliable embedded systems. This approach presents new challenges as the precise semantics of the model are hard to capture in the code. A ...
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ISBN:
(纸本)0769523560
Code generation from hybrid system models is a promising approach to producing reliable embedded systems. This approach presents new challenges as the precise semantics of the model are hard to capture in the code. A framework for generating code was introduced for single threaded/processor environments. Here, we extend it by considering code generation for distributed environments. We also define criteria for faithful implementation of the model. To this end, we define faulty and missed transitions. For preventing faulty transitions, we build on the idea of instrumentation we have developed for sound simulation of hybrid systems. Finally, we present sufficient conditions to avoid missed transitions and provide examples.
Java's popularity, facilities and platform independence have made it an interesting language for the realtime community. The RTSJ (real-time Specification for Java) is a Java extension to allow the development of...
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ISBN:
(纸本)0769523560
Java's popularity, facilities and platform independence have made it an interesting language for the realtime community. The RTSJ (real-time Specification for Java) is a Java extension to allow the development of real-time systems. RTSJ does not supply any support for the development of real-timedistributed systems. The goal of this work is to define support for this type of systems, based on RMI (Remote Method Invocation). However, the high diversity of real-time systems implies that there is not a single RT-RMI definition that satisfies their requirements. This article presents the basics of two real-time RMI approaches: safety critical RMI, to support hard real-time and high integrity requirements, and Quality of Service RMI for soft real-time systems, which is based on resource reservation to provide some minimal required quality.
The latest version of real-time CORBA defines a Distributable Thread primitive to support real-timecomputing in a dynamic distributed environment. However, this standard does not provide support for making and enforc...
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ISBN:
(纸本)0769523471
The latest version of real-time CORBA defines a Distributable Thread primitive to support real-timecomputing in a dynamic distributed environment. However, this standard does not provide support for making and enforcing global decisions. This paper describes the framework for a distributed Scheduling Service (DSS) that provides globally sound decision-making and scheduling enforcement to real-timedistributed systems. The paper describes the design and implementation of the framework, as well as preliminary performance results.
To realize location-based services, it is essential to handle the extreme situation that must cope with a very large volume, at least millions, of moving items. In this paper, we describe a location information system...
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ISBN:
(纸本)0769523560
To realize location-based services, it is essential to handle the extreme situation that must cope with a very large volume, at least millions, of moving items. In this paper, we describe a location information system prototype of GALIS, which is a cluster-based scalable distributedcomputing system architecture which consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. The proposed system contains all of the major computing nodes of GALIS architecture and is developed as a middleware on top of commercial main-memory database engines and spatial database engines, for short-term data and long-term data processing, respectively. To show the usefulness of our system, some experimental results showing clear advantages of distributedcomputing are also explained.
A challenging task in the LBS system engineering is to implement a highly scalable system architecture which can manage moderate-size configurations handling thousands of moving items as well as upper-end configuratio...
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ISBN:
(纸本)0769523471
A challenging task in the LBS system engineering is to implement a highly scalable system architecture which can manage moderate-size configurations handling thousands of moving items as well as upper-end configurations handling millions of moving items. The architecture named the GALIS is a cluster-based distributedcomputing system architecture that consists Of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone. In this paper, we explain a prototype location data management system structuring major components of GALIS by employing the TMO programming scheme, including the execution engine middleware developed to support real-timedistributedobject programming and real-timedistributedcomputing system design. We present how to generate realistic location sensing reports and how to process such location reports and location-related queries. Some experimental results showing performance factors regarding distributed query processing are also explained.
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