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370
The Design and Performance of a Real-time CORBA Event Service
- in Proceedings of OOPSLA '97, (Atlanta, GA), ACM
, 1997
"... The CORBA Event Service provides a flexible model for asynchronous communication among objects. However, the standard CORBA Event Service specification lacks important features required by real-time applications. For instance, operational flight programs for fighter aircraft have complex realtime pr ..."
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Cited by 274 (91 self)
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The CORBA Event Service provides a flexible model for asynchronous communication among objects. However, the standard CORBA Event Service specification lacks important features required by real-time applications. For instance, operational flight programs for fighter aircraft have complex realtime processing requirements. This paper describes the design and performance of an object-oriented, real-time implementation of the CORBA Event Service that is designed to meet these requirements. This paper makes three contributions to the design and performance measurement of object-oriented real-time systems. First, it illustrates how to extend the CORBA Event Service so that it is suitable for real-time systems. These extensions support periodic rate-based event processing and efficient event filtering and correlation. Second, it describes how to develop object-oriented event dispatching and scheduling mechanisms that can provide real-time guarantees. Finally, the paper presents benchmarks tha...
A Feedback-driven Proportion Allocator for Real-Rate Scheduling
, 1999
"... In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatic ..."
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Cited by 222 (27 self)
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In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatically both proportion and period. Applications with known requirements, such as isochronous software devices, can bypass the adaptive scheduler by specifying their desired proportion and/or period. As a result, our scheme provides reservations to applications that need them, and the benefits of proportion and period to those that do not. Adaptive scheduling using proportion and period has several distinct benefits over either fixed or adaptive priority based schemes: finer grain control of allocation, lower variance in the amount of cycles allocated to a thread, and avoidance of accidental priority inversion and starvation, including defense against denial-of-service attacks. This paper descr...
AQuA: An Adaptive Architecture that Provides Dependable Distributed Objects,
- Proc. of 17th IEEE Symposium on Reliable Distributed Systems,
, 1998
"... ..."
The Design of the tao real-time object request broker
- Computer Communications
, 1998
"... Many real-time application domains can benefit from flexible and open distributed architectures, such as those defined by the CORBA specification. CORBA is an architecture for distributed object computing being standardized by the OMG. Although CORBA is well-suited for conventional request/response ..."
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Cited by 145 (0 self)
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Many real-time application domains can benefit from flexible and open distributed architectures, such as those defined by the CORBA specification. CORBA is an architecture for distributed object computing being standardized by the OMG. Although CORBA is well-suited for conventional request/response applications, CORBA implementations are not yet suited for real-time applications due to the lack of key quality of service (QoS) features and performance optimizations. This paper makes three contributions to the design of realtime CORBA systems. First, the paper describes the design of TAO, which is our high-performance, real-time CORBAcompliant implementation that runs on a range of OS platforms with real-time features including VxWorks, Chorus, Solaris 2.x, and Windows NT. Second, it presents TAO’s realtime scheduling service that can provide QoS guarantees for deterministic real-time CORBA applications. Finally, the paper presents performance measurements that demonstrate the effects of priority inversion and non-determinism in conventional CORBA implementations and how these hazards are avoided in TAO. 1
An Overview of the Real-time CORBA Specification
- IEEE COMPUTER
, 2000
"... To be an effective platform for performance-sensitive real-time systems, distributed object computing middleware must support application quality of service (QoS) requirements end-toend. This article describes how the OMG's Real-time CORBA specification defines standard policies and mechanisms ..."
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Cited by 106 (14 self)
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To be an effective platform for performance-sensitive real-time systems, distributed object computing middleware must support application quality of service (QoS) requirements end-toend. This article describes how the OMG's Real-time CORBA specification defines standard policies and mechanisms that permit the specification and enforcement of end-to-end QoS.
Host Load Prediction Using Linear Models
, 2000
"... This paper evaluates linear models for predicting the Digital Unix five-second host load average from 1 to 30 seconds into the future. A detailed statistical study of a large number of long, fine grain load traces from a variety of real machines leads to consideration of the Box-Jenkins models (AR ..."
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Cited by 98 (14 self)
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This paper evaluates linear models for predicting the Digital Unix five-second host load average from 1 to 30 seconds into the future. A detailed statistical study of a large number of long, fine grain load traces from a variety of real machines leads to consideration of the Box-Jenkins models (AR, MA, ARMA, ARIMA), and the ARFIMA models (due to self-similarity.) We also consider a simple windowed-mean model. The computational requirements of these models span a wide range, making some more practical than others for incorporation into an online prediction system. We rigorously evaluate the predictive power of the models by running a large number of randomized testcases on the load traces and then data-mining their results. The main conclusions are that load is consistently predictable to a very useful degree, and that the simple, practical models such as AR are sufficient for host load prediction. We recommend AR(16) models or better for host load prediction. We implement an online host load prediction system around the AR(16) model and evaluate its overhead, finding that it uses miniscule amounts of CPU time and network bandwidth
A Framework-Based Approach to the Development of Network-Aware Applications
- IEEE TRANSACTIONS ON SOFTWARE ENGINEERING
, 1998
"... Modern networks provide a QoS (quality of service) model to go beyond best-effort services, but current QoS models are oriented towards low-level network parameters (e.g., bandwidth, latency, jitter). Application developers, on the other hand, are interested in quality models that are meaningful to ..."
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Cited by 83 (10 self)
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Modern networks provide a QoS (quality of service) model to go beyond best-effort services, but current QoS models are oriented towards low-level network parameters (e.g., bandwidth, latency, jitter). Application developers, on the other hand, are interested in quality models that are meaningful to the end-user and therefore struggle to bridge the gap between network and application QoS models. Examples of application quality models are response time, predictability, or a budget (for transmission costs). Applications that can deal with changes in the network environment are called network-aware. A network-aware application attempts to adjust its resource demands in response to network performance variations. This paper presents a framework-based approach to the construction of networkaware programs. At the core of the framework is a feedback loop that controls the adjustment of the application to network properties. The framework provides the skeleton to address two fundamental challe...
Applying Patterns to Develop Extensible ORB Middleware
, 1998
"... Distributed object computing forms the basis for nextgeneration application middleware. At the heart of distributed object computing are Object Request Brokers (ORBs), which automate many tedious and error-prone distributed programming tasks. This article presents a case study of key design patterns ..."
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Cited by 78 (29 self)
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Distributed object computing forms the basis for nextgeneration application middleware. At the heart of distributed object computing are Object Request Brokers (ORBs), which automate many tedious and error-prone distributed programming tasks. This article presents a case study of key design patterns needed to develop ORBs that can be dynamically configured and evolved for specific application requirements and system characteristics.
QoS Aspect Languages and Their Runtime Integration
- In Proceedings of the Fourth Workshop on Languages, Compilers, and Run-time Systems for Scalable Computers (LCR98
, 1998
"... . Distributed object middleware, such as CORBA, hides systemand network-specific characteristics of objects behind functional interface specifications. This simplifies development and maintenance of distributed objects, contributing to their growing acceptance. Critical applications have Quality of ..."
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Cited by 70 (18 self)
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. Distributed object middleware, such as CORBA, hides systemand network-specific characteristics of objects behind functional interface specifications. This simplifies development and maintenance of distributed objects, contributing to their growing acceptance. Critical applications have Quality of Service (QoS) requirements, however, such as real-time performance, dependability, or security, that are hidden by middleware. Because of this, application developers often bypass distributed object systems, thus gaining little or no advantage from the middleware. We have developed Quality Objects (QuO), a framework for developing distributed applications with QoS requirements. QuO provides a set of aspect languages, called Quality Description Languages (QDL), for specifying possible QoS states, the system resources and mechanisms for measuring and controlling QoS, and behavior for adapting to changing levels of available QoS at runtime. This paper describes QuO's aspect languages, their usa...
QoS-Aware Middleware for Ubiquitous and Heterogeneous Environments
- IEEE Communications Magazine
, 2001
"... Middleware systems have emerged in recent years to support applications in heterogeneous and ubiquitous computing environments. Specifically, future middleware platforms are expected to provide quality of service support, which is required by a new generation of QoS-sensitive applications such as me ..."
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Cited by 70 (0 self)
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Middleware systems have emerged in recent years to support applications in heterogeneous and ubiquitous computing environments. Specifically, future middleware platforms are expected to provide quality of service support, which is required by a new generation of QoS-sensitive applications such as media streaming and e-commerce. This article presents four key aspects of a QoS-aware middleware system: QoS specification to allow description of application behavior and QoS parameters; QoS translation and compilation to translate specified application behavior into candidate application configurations for different resource conditions; QoS setup to appropriately select and instantiate a particular configuration; and finally, QoS adaptation to adapt to runtime resource fluctuations. We also provide a comparison of existing QoS-aware middleware systems in these four aspects.
