A composite multimedia object has specific timing relationships among the different types of component media. Coordinating the real-time presentation of information and maintaining time-ordered relations among the com...
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ISBN:
(纸本)0769518575
A composite multimedia object has specific timing relationships among the different types of component media. Coordinating the real-time presentation of information and maintaining time-ordered relations among the component media is vital for satisfying quality of service (QoS) requirements. This paper proposes a formal approach to modeling and analyzing temporal aspects of SMIL documents using the Software Architecture Model (SAM), which is based on a dual formalism combining Petri nets and temporal logic. Synchronization elements of SMIL are systematically modeled by Petri nets. Useful QoS properties of SMIL documents are specified using temporal logic formulas and verified by automatic tools. timelines of SMIL document presentation are analyzed using the reachability tree technique.
There is a general trend in designing distributed control systems to give an increasing amount of autonomy to the individual nodes of such systems. Autonomous nodes interact only loosely. But also, close cooperation t...
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ISBN:
(纸本)0769510892
There is a general trend in designing distributed control systems to give an increasing amount of autonomy to the individual nodes of such systems. Autonomous nodes interact only loosely. But also, close cooperation tinder hard real-time constraints is required in certain situations. This paper analyzes approaches for structuring distributed control systems and presents an architecture integrating object-oriented frameworks, publisher/subscriber communication, and hard- and soft-real-time communication. For supporting mobile robots, wireless communication is considered in particular.
Often, the advantages attainable by objectoriented programming cannot be realised due to the widespread use of inadequate languages in the domain of realtime and distributed systems. Meeting the needs of these areas...
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ISBN:
(纸本)0769510892
Often, the advantages attainable by objectoriented programming cannot be realised due to the widespread use of inadequate languages in the domain of realtime and distributed systems. Meeting the needs of these areas to an unmatched extent, it is advocated for employing PEARL as base language, and its extension PEARL* for objectoriented software development. This paper mainly focuses on supporting software engineering for safety related embedded systems. To this end, appropriate subsets of PEARL and PEARL* are defined meeting the requirements of the Safety Integrity Levels 1, 2 and 3, respectively. It is possible to combine code associated with different Safety Integrity Levels in a transparent way, assuring that the critical parts respect some safety rules, but allowing other uncritical parts of a system to be implemented in more comfortable ways.
This paper compares interaction and communication mechanisms used in distributed control systems, focusing on object-oriented and component-based development. The standard communication model used in distributed objec...
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ISBN:
(纸本)0769510892
This paper compares interaction and communication mechanisms used in distributed control systems, focusing on object-oriented and component-based development. The standard communication model used in distributedobject-oriented systems is the remote method invocation. We argue that this client/server oriented model has some severe drawbacks when used in a control system where objects may have to broadcast information, spontaneously communicate environmental changes and where control autonomy is a crucial requirement. Therefore, we compare the traditional way of object invocation with a port-based scheme and the model of event channels. An application scenario from. robot control is used to highlight similarities and differences among these mechanisms.
The Imprecise Computation technique has been proposed as an approach to the construction of real-time systems that are able to provide both guarantee and flexibility. This paper analyzes the utilization of Imprecise C...
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ISBN:
(纸本)0769510892
The Imprecise Computation technique has been proposed as an approach to the construction of real-time systems that are able to provide both guarantee and flexibility. This paper analyzes the utilization of Imprecise Computation in the scheduling of distributedreal-time applications. First we discuss the main problems associated with that goal, and we define a task model suitable to distributed environments. Then, this paper presents an approach to the scheduling of distributed imprecise tasks. Finally, we describe specific scheduling algorithms to be used within the proposed approach.
Java-RMI is a well-known distribution middleware framework that allows the invocation of remote methods. This paper describes the extension of Java-RMI model to make the remote method calls time predictable. We identi...
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ISBN:
(纸本)0769510892
Java-RMI is a well-known distribution middleware framework that allows the invocation of remote methods. This paper describes the extension of Java-RMI model to make the remote method calls time predictable. We identify the problems of the jdk implementation of RMI and propose solutions to implement the Java-RMI extended model. This extended model and the proposed solutions are based on the Java and CORBA real-time extensions and especially on network resource reservation protocols. These extensions provide services for the network resources negotiation and to limit the latency of RMI services. The proposed solutions can be integrated in jdk1.2 RMI implementation, using the Java real-time package and RSVP implementations.
real-time simulation is an advanced mode of simulation in which the simulator components are designed to show essentially the same timing behavior that the simulation targets do. distributedreal-time simulation is a ...
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ISBN:
(纸本)0769510892
real-time simulation is an advanced mode of simulation in which the simulator components are designed to show essentially the same timing behavior that the simulation targets do. distributedreal-time simulation is a field in its infancy but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributedtime-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-orientedreal-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributedreal-time simulation and major design principles and implementation techniques for resolving those issues within the DTS framework are presented. This technical foundation has been identified through multiple major DTS experiments conducted over the years. Some issues that require further research to realize the full potentials of the DTS scheme are also discussed.
distributed applications are realized by cooperation of a group of multiple objects. In the group cooperation, a message is multicast and multiple kind of messages are in parallel sent to multiple destinations. The ob...
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ISBN:
(纸本)0769510892
distributed applications are realized by cooperation of a group of multiple objects. In the group cooperation, a message is multicast and multiple kind of messages are in parallel sent to multiple destinations. The object waits for multiple messages in conjunctive and disjunctive ways from multiple objects. In this paper, we newly define a novel precedent relation of messages exchanged among objects in presence of multicast and parallel-cast and conjunctive-receipt and disjunctive-receipt of messages.
Reusable product line software architectures and supporting components are the focus of an increasing number of software organizations attempting to reduce software costs. One essential attribute of a product line arc...
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ISBN:
(纸本)0769510892
Reusable product line software architectures and supporting components are the focus of an increasing number of software organizations attempting to reduce software costs. One essential attribute of a product line architecture is that it effectively isolate the logical, or static, aspects of the application from any product specific variations in the physical architecture, or execution environment. A primary element of this isolation is hardware and low-level software (e.g. operating system) independence. This paper describes our experiences on developing object-oriented physical architectures for large-scale reusable embedded systems, and on various ways that physical architecture attributes can be designed for flexibility without introducing volatility into the application architecture.
Even though introduced for solving the consensus problem in asynchronous distributed systems, the notion of unreliable failure detector can be used as a powerful tool for any distributed protocol in order to get bette...
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ISBN:
(纸本)0769510892
Even though introduced for solving the consensus problem in asynchronous distributed systems, the notion of unreliable failure detector can be used as a powerful tool for any distributed protocol in order to get better performance by allowing the usage of aggressive time-outs to detect failures of entities executing the protocol. In this paper we present the designing of a Failure Detection Service (FDS) based on the notion of unreliable failure detectors introduced by Chandra and Toueg. FDS is able to detect crashed objects and entities that permanently omit to send messages without imposing changes to the source code of the underlying protocols that use this service. Also, FDS provides an object-oriented interface to its subscribers and, more important, it does not add network overhead if no entity subscribes to the service. This paper can be also seen as a first step towards a distributed implementation of a heartbeat-based failure management system as defined in Fault-Tolerant CORBA specification.
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