this paper presents a memory management solution for distributedreal-time Java. the proposed model is targeted at distributed applications that require to keep their internal state and that consume a bounded memory s...
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ISBN:
(纸本)0769523560
this paper presents a memory management solution for distributedreal-time Java. the proposed model is targeted at distributed applications that require to keep their internal state and that consume a bounded memory size in their operation. the aim is to provide an alternative to the garbage collector for distributedreal-time systems and to avoid the penalties it introduces. the approach is based on the usage of scoped memory defined in the real-time Specification for Java (RTSJ). Our solution introduces constraints in the programming model and in the current distributed Java architecture. However, these are compensated by eliminating the dependency of the garbage collector in the end-to-end invocation and by achieving se cleaning with respect to the memory consumed by remote invocations.
One of the problems with Java for real-time systems is the unpredictable behavior of garbage collection (GC). GC introduces unexpected load and causes widesirable delays for real-time applications. In this paper, we p...
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ISBN:
(纸本)0769523560
One of the problems with Java for real-time systems is the unpredictable behavior of garbage collection (GC). GC introduces unexpected load and causes widesirable delays for real-time applications. In this paper, we propose a technique that reduces and bounds the memory requirements for real-time Java programs. this technique can eliminate or reduce the need for GC and allows for a more predictable execution behavior and efficient utilization of the available memory. A theoretical model is presented and a number of benchmark tests are used to evaluate this technique in PERC, NewMonics' real-time JVM, and Sun's JVM the results show that in some cases GC can be eliminated and an application's execution time decreases and becomes more predictable.
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.
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 timethe 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.
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.
Service-oriented systems are distributed systems which have the major advantage of enabling rapid composition of distributed applications, regardless of the programming languages and platforms used in developing and r...
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ISBN:
(纸本)0769523560
Service-oriented systems are distributed systems which have the major advantage of enabling rapid composition of distributed applications, regardless of the programming languages and platforms used in developing and running different components of the applications. In these systems, various capabilities are provided by different organizations as services interconnected by various types of networks. the services can be integrated following a specific workflow to achieve a mission goal for users. For large-scale service-based systems involving multiple organizations, high confidence and adaptability are of prime concern in order to ensure that users can use these systems anywhere, anytime with various devices, knowing that their confidentiality and privacy are well protected and the systems will adapt to satisfy their needs in various situations. Hence, these systems must be adaptable, situation-aware and secure. In this paper, an approach to rapid development of adaptable situation-aware secure service-based (AS) systems is presented. Our approach enables users to rapidly generate, discover, compose services into processes to achieve their goals based on the situation and adapt these processes when situation changes.
Adaptation to changing environmental conditions is a major challenge for most distributed applications. the service-oriented programming paradigm leads to an increasing number of applications that are not only meant t...
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ISBN:
(纸本)0769523560
Adaptation to changing environmental conditions is a major challenge for most distributed applications. the service-oriented programming paradigm leads to an increasing number of applications that are not only meant to provide services through standard user-interfaces hosted on desktop computers, but are to be accessible from small mobile devices as well. the integration of the different programming environments on desktop (i.e.;Windows) and mobile computers (i.e.;Java Micro Editions - J2ME) puts an extra burden on the programmer of this kind of applications. In addition, unstable conditions caused by modem infrastructures for mobile applications and varying properties of computational devices have to be considered during run-time of the application. Dynamic reconfiguration provides a powerful mechanism for adaptive computing. Within this paper, we elaborate on the extension of our previously developed Adaptive .Net framework towards CORBA and Java. Withthe introduction of new connector types, our framework is able to provide seamless support for adaptive, heterogeneous applications based on .NET Java, and CORBA. In context of our framework, applications consist of components which interact via so-called connectors. the component/connector model allows for mediating between component frameworks (Java, NET) as well as between communication protocols (CORBA, NET Remoting, sockets, etc.). Within the paper we give an overview of our adaptation framework Adaptive .NET, that includes a monitoring infrastructure, a reconfiguration platform and tools for building adaptive applications. Using a proof-of-concept application, we experimentally evaluate our connector architecture and study interoperability of Java, CORBA, and .NET objects.
this paper presents a framework for distributed in-vehicle real-time applications. the framework is based on a client/server and emitter/receiver models withreal-time extensions. the system allows the exchange of dis...
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the distributedtime-triggered simulation (DTS) scheme is a new type of approach to real-time simulation based on parallel/distributedcomputing. It requires a global time base which provides consistent real-time info...
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the distributedtime-triggered simulation (DTS) scheme is a new type of approach to real-time simulation based on parallel/distributedcomputing. It requires a global time base which provides consistent real-time information to application software running on distributed nodes. the exploitation of its full potential requires advanced computing platforms such as highly parallel computing platforms. Recent developments in the scientific foundation for DTS and the execution engines and programming tools supporting DTS are briefly reviewed.
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