Although distributedreal-time (RT) systems are intrinsically complex to develop and maintain, the use of certain object-oriented (OO) technologies such as CORBA and CORBA-RT facilitates those tasks. This is the main ...
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ISBN:
(纸本)9780769527659
Although distributedreal-time (RT) systems are intrinsically complex to develop and maintain, the use of certain object-oriented (OO) technologies such as CORBA and CORBA-RT facilitates those tasks. This is the main reason why these technologies are becoming increasingly popular. Moreover, CORBA is complemented with additional services that solve specific requirements for some applications, so developers may concentrate on the application functionality. Following this approach, this paper presents a new service that allows the synchronous scheduling of different activities in a distributed RT system in a simple and flexible way. This paper also explains how this service can be used for optimizing that access to shared resources in a distributed system and presents several experimental data that show the service performance.
As quality of service (QoS)-enabled component middleware technologies gain widespread acceptance to build distributedreal-time and embedded (DRE) systems, it becomes necessary for these technologies to support real-t...
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ISBN:
(纸本)9780769527659
As quality of service (QoS)-enabled component middleware technologies gain widespread acceptance to build distributedreal-time and embedded (DRE) systems, it becomes necessary for these technologies to support real-time publish/subscribe services, which is a key requirement of a large class of DRE systems. To date there have been very limited systematic studies evaluating different approaches to integrating real-time publish/subscribe services in QoS-enabled component middleware. This paper makes two contributions in addressing these key research questions. First, we evaluate the pros and cons of three different design alternatives for integrating publish/subscrib e services within QoS-enabled component middleware. Second, we empirically evaluate the performance of our container-based design and compare it with mature object-orientedreal-time publish/subscribe implementations. Our studies reveal that both the performance and scalability of our design and implementation are comparable to its object-oriented counterpart, which provides a key guidance to the suitability of component technologies for DRE systems.
In object-orientedreal-timecomputing scenarios, particularly where Corba is used in embedded systems with resource constraints, developers and system architects often utilize Corba object references as authorization...
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ISBN:
(纸本)9780769527659
In object-orientedreal-timecomputing scenarios, particularly where Corba is used in embedded systems with resource constraints, developers and system architects often utilize Corba object references as authorization tokens. This paper investigates the security of this method in principle, and it presents the results of the analysis of the work and computing effort necessary for a potential attacker to fabricate Corba object references to existing objects for the purpose of illegitimately gaining access to these objects at the instance of seven widely used Corba products.
This paper describes an extension to the component-based programming model to support real-time dynamic guarantee for distributed applications. The extended model aims to include an acceptance tests to component-based...
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ISBN:
(纸本)9780769527659
This paper describes an extension to the component-based programming model to support real-time dynamic guarantee for distributed applications. The extended model aims to include an acceptance tests to component-based servers at bind time. We present the mapping of our model to the CORBA component Model, the architecture to support the dynamic guarantee in component-based middleware, the implementation of this architecture in CIAO (component Integrated ACE ORB) and the result of experiments run to evaluate the cost of the mechanisms used.
Recently, new trends in application development for distributed platforms, such as the composable services model, attempt to provide more flexibility in system design, deployment and execution. Such trends, and partic...
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ISBN:
(纸本)9780769527659
Recently, new trends in application development for distributed platforms, such as the composable services model, attempt to provide more flexibility in system design, deployment and execution. Such trends, and particularly the referred composable services model, can also be beneficial in real-timedistributed embedded systems, also providing a means to support more adaptive behaviors, reacting to the execution environment or coping with system. reconfiguration. This paper explores a relatively new direction, which is the extension of the service-based model to dynamic, i.e. at run-time, composition in real-timedistributed environments, in order to support the level of flexibility and adaptibility referred above. The paper proposes an architecture to support such dynamic service composition that is based on the Flexible time Triggered communication paradigm (FTT). To achieve the desired goal, we also redefine the concepts of service and service-based application in the concept of the FTT paradigm. Finally, we show experimental results obtained with a prototype implementation of the proposed architecture that confirm its feasibility and good temporal behavior
In service-based systems, services from various providers can be integrated following specific workflows to achieve users' goals. These workflows are often executed and coordinated by software agents, which invoke...
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ISBN:
(纸本)9780769527659
In service-based systems, services from various providers can be integrated following specific workflows to achieve users' goals. These workflows are often executed and coordinated by software agents, which invoke appropriate services based on situation changes. These agents need to be deployed on underlying platforms with respect to various requirements, such as access Permission of agents, real-time requirements of workflows, and reliability of the overall system. Deploying these agents manually is often error-prone and time-consuming. Furthermore, agents need to migrate from hosts to hosts at runtime to satisfy deployment requirements. Hence, an automated agent deployment mechanism is needed In this paper, an approach to automated agent deployment in service-base systems is presented. In this approach, the deployment requirements are represented as deployment policies, and techniques are developed for generating agent deployment plans by solving the constraints specfied in deployment policies, and for generating executable code for runtime agent deployment and migration.
This paper provides three contributions to the study of quality of service (QoS) configuration in component-based DRE systems. First, we describe the challenges associated with mapping the platform-independent QoS pol...
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ISBN:
(纸本)9780769527659
This paper provides three contributions to the study of quality of service (QoS) configuration in component-based DRE systems. First, we describe the challenges associated with mapping the platform-independent QoS policies of an application into platform-dependent values of QoS parameters used to configure the behavior of QoS-enabled component middleware. Second, we describe a novel approach that uses model-transformation to map these QoS policies onto component middleware QoS configuration parameters. Third, we demonstrate the use of model-checking to verify the properties of the transformation and automate the synthesis of configuration parameters required to tune the QoS-enabled component middleware. Our results indicate that model-transformation and model-checking provide significant benefits with respect to automation, reusability, verifiability, and scalability of the QoS mapping process compared with conventional middleware configuration techniques.
Standards-based quality of service (QoS)-enabled component middletvare is increasingly being used as a platform,for developing distributedreal-time embedded (DRE) systems that execute in open environments where opera...
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ISBN:
(纸本)9780769527659
Standards-based quality of service (QoS)-enabled component middletvare is increasingly being used as a platform,for developing distributedreal-time embedded (DRE) systems that execute in open environments where operational conditions, input workload, and resource availability cannot be characterized accurately a priori. Although QoS-enabled component middleware offers many desirable features, until recently it lacked the ability to efficiently allocate resources and configure platform-specific QoS settings based on utilization of system resources and application QoS. Moreover, it has also lacked the ability to monitor and enforce application QoS requirements. This paper presents two contributions to research on adaptive resource management for component-based DRE systems. First, we describe the structure and functionality of the Resource Allocation and Control Engine (RACE), which is an open-source adaptive resource management framework built atop standards-based QoS-enabled component iniddleware. Second, we demonstrate the effectiveness of RACE in the context of a representative DREsystem: NASA's Magnetospheric Multi-scale Mission system.
We propose a new, minimal specification for real-time Java,for safety critical applications. The intention is to provide a profile that supports programming of applications that can be validated against safety critica...
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ISBN:
(纸本)9780769527659
We propose a new, minimal specification for real-time Java,for safety critical applications. The intention is to provide a profile that supports programming of applications that can be validated against safety critical standards such as DO-178B[15]. The proposed profile is in line with the Java specification request JSR-302: Safety Critical Java Technology, which is still under discussion. In contrast to the current direction of the expert group for the JSR-302 we do not subset the rather complex real-time Specification for Java (RTSJ). Nevertheless, our profile can be implemented on top of an RTSJ compliant JVM.
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