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Object-Oriented Real-Time Distributed Computing, 1999. (ISORC '99) Proceedings. 2nd IEEE International Symposium on

Date 2-5 May 1999

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  • Proceedings 2nd IEEE International Symposium on Object-Oriented Real-Time Distributed Computing (ISORC'99) (Cat. No.99-61702)

    Publication Year: 1999
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    Freely Available from IEEE
  • Author index

    Publication Year: 1999 , Page(s): 351 - 352
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    Freely Available from IEEE
  • Architectural techniques for the description and validation of distributed real-time systems

    Publication Year: 1999 , Page(s): 323 - 331
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    Our goal is to settle techniques for the validation of real time distributed systems. We opted for executable models and simulation techniques. Our approach is to work at the architectural level of a system abstraction. The software architecture is understood as a set of structures comprising software components with external properties and relationships among them. We devised a language to describe those components and the logical structure of the architecture. It is a specialization and extension of object oriented modeling languages designed to deal with concurrency, reactivity and architectural concerns. This language is based on a notion of components defined similarly to the class notion, extended for the timing requirements. Execution and simulation are driven to validate behaviors with respect to desired properties View full abstract»

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  • Resource managers for QoS in CORBA

    Publication Year: 1999 , Page(s): 213 - 222
    Cited by:  Papers (4)
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    Multimedia applications require support for quality of service (QoS). The need for reusable and maintainable code also means that these kinds of applications are developed in a distributed object system. To address the support of QoS in middleware, we propose a lightweight model to manage QoS constraints in this kind of environment. This model is based on two types of objects: micro-QoS managers (μQoS-Mngrs) and resource managers (R-Mngrs). A μQoS-Mngr is associated with an application, and it handles the QoS contract, the QoS mapping and the QoS monitoring. Each R-Mngr is responsible for QoS management for a specific resource, including admission control, real-time scheduling and monitoring. The μQoS-Mngrs and the R-Mngrs co-operate, using the middleware, to ensure end-to-end QoS management. This paper focuses on the R-Mngrs and it gives an overview of our implementation on a CORBA platform in the context of a video-on-demand (VOD) application View full abstract»

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  • The PERCO platform

    Publication Year: 1999 , Page(s): 245 - 250
    Cited by:  Papers (1)
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    The PERCO platform is an industry-provided software platform that specifically addresses the requirements of highly available, dependable autonomous systems. Its basic tenet is to use UML specifications to build as much of the application as possible, while integrating real-time and fault-tolerant properties at the architectural level. PERCO was designed and built within the Alcatel-Thomson Common Laboratory (LCAT) View full abstract»

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  • Protocols and ports: reusable inter-object behavior patterns

    Publication Year: 1999 , Page(s): 332 - 339
    Cited by:  Papers (10)
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    We introduce the concept of protocols. A protocol is a formal specification of potentially complex reusable pattern of inter-object behavior. To make it reusable, a protocol is defined independently of any specific object classes or instances. Even though they are defined independently of individual classes, we demonstrate how, using the notion of two-way interfaces called ports, protocols can be formally bound to structures of collaborating objects. This gives us a framework in which it is possible to formally verify if a particular combination of objects can indeed achieve the desired inter-object behavior. A further advantage is that programs with protocol specifications are more understandable and more maintainable than traditional object oriented programs since the required high level behavior is explicit. We describe both protocols and ports using the base concepts of the recent Unified Modeling Language (UML) standard View full abstract»

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  • A tool for object-oriented dynamic modeling

    Publication Year: 1999 , Page(s): 111 - 116
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    The commonly recognized weakness of modern object oriented design and implementation methodologies lies in their superficial treatment of inter-object dynamics. The paper describes a software toolbox called ODYMOT that integrates a number of approaches to the problem of behavior modeling. In order to achieve design flexibility, a two-layer object design architecture is used that blends together object oriented design concepts with those of high level Petri nets. The Petri net representation creates an additional access layer of object architecture, providing meta level object control with the sequencing of method execution. This modeling approach allows one, both mathematically and pragmatically, to achieve a more precise and flexible description and implementation of real time and distributed models View full abstract»

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  • Sense: a Service Navigation System linked to a real-time advertising distribution service

    Publication Year: 1999 , Page(s): 121 - 126
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    Sense: A Service Navigation System is an agent system supporting interaction between the end user (consumer) and service provider (producer) in an open, distributed object environment. It navigates among the latest multimedia network services based on the end user's wishes, profile and situations. Its service navigation strategy is a key feature of Sense; it navigates based not merely on pre-registered user information, but taking into consideration the history of service selection by the user, advertising information from the service provider and other clues. Moreover, Sense makes use of object services available in the open distributed processing environment, such as traders and service type repositories, enabling it to take the initiative in proposing the latest multimedia network services View full abstract»

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  • An efficient middleware architecture supporting time-triggered message-triggered objects and an NT-based implementation

    Publication Year: 1999 , Page(s): 54 - 63
    Cited by:  Papers (34)
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    The time-triggered message-triggered object (TMO) structuring scheme has been established to remove the limitation of conventional object structuring techniques in developing applications containing real time (RT) distributed computing components. It is a natural and syntactically small but semantically powerful extension of the object oriented design and implementation techniques which allows the system designer to abstractly and yet accurately specify timing characteristics of data and function components of high level distributed computing objects. It is a unified approach for design and implementation of both RT and non-RT distributed applications. A cost-effective way to support TMO-structured distributed RT programming is to build a TMO execution engine as a middleware running on well established commercial software/hardware platforms. We present an efficient middleware architecture named TMO Support Middleware (TMOSM) which can be easily adapted to many commercial-off-the-shelf (COTS) platforms. The performance of a prototype implementation of TMOSM running on Windows NT platforms is also discussed View full abstract»

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  • Holistic object-oriented modelling of distributed automotive real-time control applications

    Publication Year: 1999 , Page(s): 85 - 92
    Cited by:  Papers (4)
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    The automotive industry has been late in introducing object oriented (OO) analysis, design, and programming, compared to many other businesses. This is partly due to the fact that OO programming has been considered too expensive in terms of computational resources, but also because there are elements in the application functions for which OO methods do not give sufficient support. Nevertheless, OO techniques provide many advantages, and we discuss how they can be used for automotive real time control applications. The suggested approach is holistic in the following respects: it treats functionality on the vehicle level rather than on individual control units; it includes both the embedded system and its environment; and it considers both hardware and software View full abstract»

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  • Theory versus practice in real-time computing with the JavaTM platform

    Publication Year: 1999 , Page(s): 105 - 108
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    The discipline of computer science has always featured a large gap between theory and practice. For example, both the object oriented paradigm and garbage collection techniques go back to at least the 1960s (H. Schorr and W. Waite, 1967; O.J. Dahl and K. Nygard, 1966) but they have only seen widespread commercial acceptance this decade. The Java TM programming language has been an important factor leading to the commercial popularization of these techniques. The field of real time computing has suffered from a particularly acute disconnect between theory and practice. JavaTM technology can be applied to the building of real time systems through a set of standard extensions to the JavaTM platform. A set of extensions that bring the core benefits of the platform to real time will advance the commercial state of the art. It will help to narrow the gap between theory and practice. The paper explores different aspects of computer systems theory as applied to real time systems. It analyzes whether they are ready to be reduced to practice and standardized View full abstract»

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  • In pursuit of correct paradigms for object-oriented real-time distributed systems

    Publication Year: 1999 , Page(s): 271 - 279
    Cited by:  Papers (1)
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    Real time distributed applications based on object oriented technology raise many complex issues, most of them still open. We elaborate on the reasons why traditional paradigms, found adequate for tackling simple problems, cannot help in addressing these complex issues. A detailed illustration is given with a problem in modular avionics, which has been addressed by resorting to proof based system engineering, an emerging discipline aimed at coping with real world problems complexity. Drawing from our experience with partners in industry, we report on why such paradigms and technologies as object orientation, distributed transactions, distributed architectures, transactional monitors, can be contemplated for the construction of real time distributed systems, provided that appropriate online decision making algorithms and protocols are resorted to View full abstract»

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  • Using multiple feedback loops for object profiling, scheduling and migration in soft real-time distributed object systems

    Publication Year: 1999 , Page(s): 291 - 300
    Cited by:  Papers (10)  |  Patents (5)
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    Complex soft real time distributed object systems require object profiling, scheduling and migration algorithms to respond to transient changes in the load or in the availability of the resources. We have developed a resource management system for a soft real time distributed object system that is based on a three level feedback loop which employs a profiling algorithm that monitors the usage of the resources, a least laxity scheduling algorithm that schedules the tasks, and hot spot and cooling algorithms that allocate and migrate objects to balance the load on the resources. The resource management system consists of a single (but possibly replicated and distributed) resource manager, and profilers and schedulers located on each of the processors in the distributed system View full abstract»

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  • Automated dependability analysis of UML designs

    Publication Year: 1999 , Page(s): 139 - 144
    Cited by:  Papers (12)
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    The paper deals with the automatic dependability analysis of systems designed using UML. An automatic transformation is defined for the generation of models to capture systems dependability attributes, like reliability. The transformation concentrates on structural UML views, available early in the design, to operate at different levels of refinement, and tries to capture only the information relevant for dependability to limit the size (state space) of the models. Due to the modular construction, these models can be refined later as more detailed, relevant information becomes available. Moreover a careful selection of those critical parts to be detailed allows one to avoid explosion of the size. An implementation of the transformation is in progress and will be integrated in the toolsets available for the ESPRIT LTR HIDE project View full abstract»

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  • Applying use cases for the requirements validation of component-based real-time software

    Publication Year: 1999 , Page(s): 75 - 84
    Cited by:  Papers (2)
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    Component based software development is a promising way to improve quality, time to market and handle the increasing complexity of software for real time systems. The basic properties of an event triggered component model for real time software are introduced. For the early exposure of design errors, a process for the simulation based validation of component based software applying use cases is presented. A template for structuring use cases helps gathering the course oriented requirements which describe the required behaviour of the composed software. Requirements sequence diagrams are extracted from the use cases and compared with the simulated behaviour of the component based software. A case study of a power window control from the automotive body electronics domain demonstrates practical experience with applying use cases for the requirements validation View full abstract»

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  • Embedded platforms for distributed real-time computing: challenges and results

    Publication Year: 1999 , Page(s): 147 - 152
    Cited by:  Papers (2)
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    Object oriented techniques have been along the last decade one of the most useful programming paradigms. However, for distributed embedded systems, the semantic gap between the object orientation layer and the underlying infrastructure is extremely large. This gap can be narrowed, should the embedded system platform provide semantically rich communication and management services. The paper outlines our research effort in the provision of such services by CAN based (Controller Area Network) systems View full abstract»

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  • v-Promela: a visual, object-oriented language for SPIN

    Publication Year: 1999 , Page(s): 14 - 23
    Cited by:  Papers (3)
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    Describes the design of VIP (Visual Interface for Promela), a graphical front-end to the model checker SPIN. VIP supports a visual formalism, called v-Promela, that connects the model checker to modern hierarchical notations for the specification of object-oriented, reactive systems. The formalism is comparable to formalisms such as UML-RT (Unified Modeling Language for Real-Time systems), ROOM (Real-time Object-Oriented Modeling) and Statecharts, but is presented in this paper in a framework that allows us to combine the benefits of a visual, hierarchical specification method with the power of LTL (linear temporal logic) model checking provided by SPIN. Like comparable formalisms, VIP can describe hierarchies of behaviour and of system structure. The formalism is designed to be transparent to the SPIN model checker itself, by allowing all central constructs to be translated mechanically into basic Promela, as already supported by the existing model checker View full abstract»

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  • OPERA: a CORBA-based architecture enabling distributed real-time simulations

    Publication Year: 1999 , Page(s): 241 - 244
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    The mission of the EU-funded OPERA (Operator Training by Distributed Real-Time Simulations) project (ESPRIT Project No. 24950) is the training of operators in the chemical industry by means of flexible and configurable simulation applications running in a cost-effective IT environment. This paper outlines how the problem of real-time operation combined with the requirement for high-performance computing may be solved in a standard environment. The OPERA system provides a way to integrate hybrid simulation models and is highly scalable. It runs either on a single computer or on a multiprocessor LAN cluster. OPERA's results appear to be useful for solving many problems, far beyond the initial requirements in the domain of distributed simulation View full abstract»

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  • Implementing highly-available WWW servers based on passive object replication

    Publication Year: 1999 , Page(s): 259 - 262
    Cited by:  Papers (2)
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    We investigate issues related to building highly available World Wide Web (WWW) servers on workstation clusters. We present a novel architecture that includes a dynamic Domain Name System (DNS) and a WWW server based on passive object replication. This architecture allows us to reduce the service down-time of a WWW server without impacting on the Hyper Text Transfer Protocol (HTTP) protocol (and thus on the WWW client software). We implement this architecture in our department and we show some experimental results that analyze, given a batch of HTTP requests, the average response time to a request and the average time of WWW service unavailability due to object crashes View full abstract»

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  • A framework for building environment-aware software

    Publication Year: 1999 , Page(s): 237 - 240
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    In this paper, we propose a software architecture for building environment-aware software that runs in various real-time computing environments by adapting programs to their respective environments. The framework is especially suitable for embedded computing environments, since the environments are required to support various types of computers View full abstract»

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  • Prediction of fault-proneness at early phase in object-oriented development

    Publication Year: 1999 , Page(s): 253 - 258
    Cited by:  Papers (4)
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    To analyse the complexity of object-oriented software, several metrics have been proposed. Among them, Chidamber and Kemerer's (1994) metrics are well-known object-oriented metrics. Also, their effectiveness has been empirically evaluated from the viewpoint of estimating the fault-proneness of object-oriented software. In the evaluations, these metrics were applied, not to the design specification but to the source code, because some of them measure the inner complexity of a class, and such information cannot be obtained until the algorithm and the class structure are determined at the end of the design phase. However, the estimation of the fault-proneness should be done in the early phase so as to effectively allocate effort for fixing the faults. This paper proposes a new method to estimate the fault-proneness of an object class in the early phase, using several complexity metrics for object-oriented software. In the proposed method, we introduce four checkpoints into the analysis/design/implementation phase, and we estimate the fault-prone classes using applicable metrics at each checkpoint View full abstract»

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  • Evaluating architecture implementation alternatives based on adaptability concerns

    Publication Year: 1999 , Page(s): 155 - 158
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    Software is rarely designed for ultimate adaptability, performance or reusability but rather it is a compromise of multiple considerations. Even for a simple architecture specification, one may identify many alternative implementations. The paper makes an attempt to depict the space of implementation alternatives of architectures, and to define rules for selecting them. The applicability of this approach is illustrated by means of a simple design problem View full abstract»

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  • Adaptive QoS support for distributed, Java-based applications

    Publication Year: 1999 , Page(s): 203 - 212
    Cited by:  Papers (1)  |  Patents (2)
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    Describes SRI International's ERDoS (End-to-end Resource management of Distributed Systems) project. ERDoS is a distributed middleware with comprehensive resource management support, including application scheduling, resource allocation and graceful adaptation. We discuss how we have implemented this resource management as part of the Java Virtual Machine (JVM). We have also provided a resource management application programming interface (API) as a new Java class library. The ERDoS development environment enables nonprogrammers to create complex distributed applications by simply stringing together multiple Java methods. The ERDoS runtime environment utilizes a structuring algorithm to create a distributed Java application dynamically, and then provides allocation, scheduling and content-based, graceful, adaptive QoS support to these applications. We demonstrate the benefits of content-based adaptation and of dynamic structuring of distributed applications, using a set of video applications View full abstract»

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  • Which models and architectures of distributed real-time computing systems suit which application area?

    Publication Year: 1999 , Page(s): 286 - 288
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    A real time system must produce the intended results at the intended points of real time determined by its environment, otherwise the system has failed (H. Kopetz, 1997). For the purpose of this discussion, we consider two types of environments that contain real time computer systems: (i) static environments, where the frequency of the service requests on the computer system are constrained by a priori known environmental characteristics; (ii) dynamic environments, where it is possible to specify peak-load-service-request rates probabilistically only, e.g., a military command and control system that has to adapt dynamically to the n priori unknown threats of the enemy. We feel that these two fundamentally different environments of distributed real time computer systems demand different system models and different implementation strategies View full abstract»

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  • An adaptive scheduling approach in real-time CORBA

    Publication Year: 1999 , Page(s): 301 - 309
    Cited by:  Papers (3)
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    CORBA is an emerging middleware infrastructure with open standardization that is receiving a good acceptance since it allows easier programming of distributed objects. CORBA is being extended through the specification of interfaces and necessary abstractions to support applications with real time constraints. These new abstractions will enable a variety of programming models for real time applications. The paper presents an adaptive programming model for distributed real time applications using CORBA concepts. The model combines the time polymorphic invocation technique with the (m,k)-firm guarantee View full abstract»

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