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Full-Text Articles in Physical Sciences and Mathematics
A Single-Stroke Orientation-Orient Gesture System, Yike Hu
A Single-Stroke Orientation-Orient Gesture System, Yike Hu
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No abstract provided.
Transient Data Sharing Among Mobile Programs, Jerome Plun, Gruia-Catalin Roman
Transient Data Sharing Among Mobile Programs, Jerome Plun, Gruia-Catalin Roman
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Mobile computing represents a major point of departure from the traditional distributed computing paradigm. The potentially very large number of independent computing units, a decoupled computing style, frequent disconnections, continuous position changes, and the location-dependent nature of the behavior and communication patterns present designers with unprecedented challenges in the areas of modularity and dependability. This paper describes a modular approach to specifying and reasoning about of mobile computing. Its novelty rests with the notion of allowing transient (location-dependent) data sharing among programs which move in space. The notation is a direct extension of that used in UNITY and reasoning about …
An Efficient Signaling Structure For Atm Networks, Dakang Wu
An Efficient Signaling Structure For Atm Networks, Dakang Wu
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As ATM becomes widely accepted as the communication standard for high speed networks, the signaling system structure and protocols that support ATM become more and more important. To support existing, future and unknown applications, the signalign system has to be very flexible and efficient. In this paper we define the signaling problem, present several possible signaling system structures, compare the advantages and disadvantages of these systems, and then we propose a new signaling system structure. The fundamental idea of the new signaling system is the logical separation of the signaling system structure from the underlying communication network, even though they …
Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, T. Paul Mccartney, Ram Sethuraman, Bala Swaminathan And Todd Rogers
Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, T. Paul Mccartney, Ram Sethuraman, Bala Swaminathan And Todd Rogers
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No abstract provided.
Efficient Demultiplexing Of Network Packets By Automatic Parsing, Mahesh Jayaram, Ron K. Cytron
Efficient Demultiplexing Of Network Packets By Automatic Parsing, Mahesh Jayaram, Ron K. Cytron
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Packet filters are a mechanism for efficiently demultiplexing network packets to application endpoints. There is currently no general, formal specification method for packet filters that allows for easy or efficient composition of specifications. In this paper we present an automatic approach that achieves all of these goals. We approach packet filter specification as a language recognition problem: each filter is represented by a context-free grammar, whose language is the set of packets the filter should accept. Thus, packet filters can be formulated through a general, well defined specification; further, the grammar-based approach simplifies filter composition, which is essential where scalability …
Maintaining High Throughput During Overload In Atm Switches, Jonathan S. Turner
Maintaining High Throughput During Overload In Atm Switches, Jonathan S. Turner
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This report analyzes two popular heuristics for ensuring packet integrity in ATM switching systems. In particular, we analyze the behavior of packet tail discarding, in order to understand how the packet level link efficiency is dependent on the rates of individual virtual circuits and the degre of the imposed overload. In addition, we study early packet discard and show that the queue capacity needed to achieve high efficiency under worst-case conditions grows with the number of virtual circuits and we determine the efficiency obtainable with more limited queue capacities. Using the insights from these analyses, extensions to early packet discard …
Real-Time Upcalls: A Mechanism To Provide Real-Time Processing Guarantees, Raman Gopalakrishna, Guru M. Parulkar
Real-Time Upcalls: A Mechanism To Provide Real-Time Processing Guarantees, Raman Gopalakrishna, Guru M. Parulkar
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Real-time upcalls (RTUs) are an operating systems mechanism that can be used by applications to efficiently schedule code segments (or handlers) that must execute periodically. While the mechanism was conceibed to support protocol processing with quality-of-service guarantees for networked multimedia applicatoins it is general enough to be applicable in other domains like real-time image processing. Until now real-time threads have been the only mechanism for implementing protocols in user space with QoS guarantees. The RTU mechanism avoids the implementation complexity of the thread based approach while retaining its ability to ensure real-time behavior. In addition, our design simplifies protocol code, …
Issues In Distributed Control For Atm Networks, Jonathan S. Turner
Issues In Distributed Control For Atm Networks, Jonathan S. Turner
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Asynchronous Transfer Mode (ATM) network technology is expected to become a central part of the emerging global information infrastructure. ATM networks introduce a number of features that distinguish them from earlier technologies and introduce new issues in network control. This paper offers a framework for precisely defining and analyzing alternative approaches to the distributed control of ATM networks and explores some of the key design issues through a series of examples. It is hoped that it will provide a useful foundation for researchers in networking and distributed computing interested in exploring these issues further and developing more complete solutions.
Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman
Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman
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No abstract provided.
Can Declared Strategy Voting Be An Effective Instrument For Group Decision-Making?, Lorrie Faith Cranor
Can Declared Strategy Voting Be An Effective Instrument For Group Decision-Making?, Lorrie Faith Cranor
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The goal of this research is to determine whether declared strategy voting can be an effective tool for group decision-making. Declared strategy voting is a novel group decision-making procedure in which preference is specified using voting strategies - first-order mathematical functions that specify a choice in terms of zero or more parameters. This research will focus on refining the declared strategy voting concept, developing an accessible implementation of declared strategy voting that can be used for mock elections, assessing the potential impacts of declared strategy voting, and evaluating the effectiveness of declared strategy voting for group decision-making. This proposal describes …
An Oo Encapsulation Of Lightweight Os Concurrency Mechanisms In The Ace Toolkit, Douglas C. Schmidt
An Oo Encapsulation Of Lightweight Os Concurrency Mechanisms In The Ace Toolkit, Douglas C. Schmidt
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This paper describes the design of the ACE object-oriented thread encapsulation class library. The architecture of this class library is presented from an end-user and internal design perspective and several key design issues are discussed. Readers should gain an understanding of the overall design approach as well as the tradeoffs between various software quality factors such as performance, portability, and extensibility.
Error Control For Continuous Media And Multipoint Applications, Christos Papadopoulos, Guru Parulkar
Error Control For Continuous Media And Multipoint Applications, Christos Papadopoulos, Guru Parulkar
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High-bandwidth multimedia applications pose new challenges to error control. These include the support of error control for Continuous Media (CM) streams and the scalable support of error control in multipoint applications where the number of participants is large. Current error control mechanisms provide no support for the above applications. In this report we present new error control mechanisms that provide the required support. Continuous media applications have strict timing requirements which greatly affect recovery. To support continuous media applications we have designed and implemented a point-to-point error control mechanism which features the following: (1) selective repeat retransmission, (2) conditional retransmission, …
Hart's Critics On Defeasible Concepts And Ascriptivism, Ronald P. Loui
Hart's Critics On Defeasible Concepts And Ascriptivism, Ronald P. Loui
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Hart's "Ascription of Responsibility and Rights" is where we find perhaps the first clear pronouncement of defeasibility and the technical introduction of the term. The paper has been criticised, disavowed, and never quite fully redeemed. Its lurid history is now being used as an excuse for dismissing the importance of defeasibility. Quite to the contrary, Hart's introduction of defeasibility has uniformly been regarded as the most agreeable part of the paper. The critics' wish that defeasibility could be better expounded along the lines of a Wittgensteinian game-theoretic semantics has largely been fulfilled. Even the most contentious part of the paper, …
Synchronized Data Objects, Marin Bezic
Synchronized Data Objects, Marin Bezic
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Synchronized Data Objects (SDOs) are presented as a method of encapsulating, in the datatype definition, synchronization protocols that are used to control information exchange. SDOs are presented in the context of I/O abstraction, a programming model that seeks to separate communication from computation in order to support dynamic end-user configuration of distrivuted applications. SDOs can be used to implement a variety of synchronization paradigms, including remote invalidation, demand-driven data streams, remote procedure call, and promises. An implementation of SDOs is described in the context of The Programmers' Playground, a distributed application development environment that supports the I/O abstraction programming model. …
Design Of A Tool For Rapid Prototyping Of Communication Protocols, Aniruddha Gokhale, Ron Cytron, George Varghese
Design Of A Tool For Rapid Prototyping Of Communication Protocols, Aniruddha Gokhale, Ron Cytron, George Varghese
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We present a new tool for automatically generating prototypes of communication protocols on a wide variety of platforms. Our goal is to reduce design time, enhance portability, and accommodate optimizations automatically. Users of the tool are required to provide an abstract implementation of the protocol in C++ without worrying about the underlying operating system specific system calls. Instead, the user employs high-level interface functions provided by the tool to interact with the underlying operating system. Users also need not worry about complex packet formats that involve fields of various bit and byte lengths. Instead, they use simple C/C++ struct declarations …
Aras: Asynchronous Risc Architecture Simulator, Chia-Hsing Chien, Mark A. Franklin, Tienyo Pan, Prithvi Prabhu
Aras: Asynchronous Risc Architecture Simulator, Chia-Hsing Chien, Mark A. Franklin, Tienyo Pan, Prithvi Prabhu
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In this paper, an asynchronous pipeline instruction simulator, ARAS is presented. With this simulator, one can design selected instruction pipelines and check their performance. Performance measurements of the pipeline configuration are obtained by simulating the execution of benchmark programs on the machine architectures developed. Depending on the simulation results obtained by using ARAS, the pipeline configuration can be altered to improve its performance. Thus, one can explore the design space of aynchronous pipeline architectures.
Pac Learing Of One-Dimensional Patterns, Paul W. Goldberg, Sally A. Goldman, Stephen D. Scott
Pac Learing Of One-Dimensional Patterns, Paul W. Goldberg, Sally A. Goldman, Stephen D. Scott
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Developing the ability to recognize a landmark from a visual image of a robot's current location is a fundamental problem in robotics. We consider the problem of PAC-learning the concept class of geometric patterns where the target geometric pattern is a configuration of k points on the real line. Each instance is a configuration of n points on the real line, where it is labeled according to whether or not it visually resembles the target pattern. To capture the notion of visual resemblance we use the Hausdorff metric. Informally, two geometric patterns P and Q resemble each othe runder the …
Distributed Debugging With I/O Abstraction, Andrew S. Koransky
Distributed Debugging With I/O Abstraction, Andrew S. Koransky
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This thesis presents a simple, yet powerful, set of mechanisms for testing and debugging distributed applications consisting of modules that communicate through well-defined data interfaces. The tools allow default or programmer-defined functions to be attached to various communication events so that particular data values at interesting points in the program are made available for testing and debugging. The debugging status of each component of the communication interface can be controlled separately so that various debugging information can be turned on and off during program execution. By attaching breakpoints to programmer-defined fucntions in a standard debugger, fine-grained examination of each module …
Formal Specification Of A Dynamically Configurable Distributed System, Ram Sethuraman, Kenneth J. Goldman
Formal Specification Of A Dynamically Configurable Distributed System, Ram Sethuraman, Kenneth J. Goldman
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The Programmers' Playground is a programming environment that supports end-user construction of distributed multimedia applications. The system implements a new programming model that is based, in part, upon ideas from the formal I/O automaton model of Lynch and Tuttle. Important features of The Programmers' Playground are a separation of communication and computation and graphical support for dynamic reconfiguration. This paper provides a formal specification of the Playground programming model and runtime system in terms of the I/O automaton model on which it is based. Exploiting the compositionality properties of the I/O automaton model, the formal specification is describd as a …
Redesigning The Bsd Callout And Timer Facilities, Adam M. Costello, George Varghese
Redesigning The Bsd Callout And Timer Facilities, Adam M. Costello, George Varghese
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We describe a new implementation of the BSD callout and timer facilities. Current BSD kernels take time proportional to the number of outstanding timers to set or cancel timers. Our implementation takes constant time to start, stop, and maintain timers; this leads to a highly scalable design that can support thousands of outstanding timers without much overhead. Unlike the existing implementation, our routines are guaranteed to lock out interrupts only for a small, bounded amount of time. We also extend the setitimer() interface to allow a process to have multiple outstanding timers, thereby reducing the need for users to maintain …
User Interface Applications Of A Multi-Way Constraint Solver, T. Paul Mccartney
User Interface Applications Of A Multi-Way Constraint Solver, T. Paul Mccartney
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Constraints are widely recognized as a useful tool for user interface constructino. Through constraints, relationships among user interface components can be defined declaratively, leaving the task of relationship management to a constraint solver. Multi-way constraint solvers supporting constraint hierarchies provide a means to specify preferential constraint relationships with a dynamically changing computation flow, making them especially well suited to interactive user interfaces. However, previous such constraint solvers lack the ability to enforce inequalities or to effectively handle cyclic constraint relationships. These deficiencies limit the problems that could be solved using a constraint-based approach. This paper presents a new algorithm called …
Reasoning About Program Interactions In The Presence Of Mobility, Gruia-Catalin Roman, Peter J. Mccann
Reasoning About Program Interactions In The Presence Of Mobility, Gruia-Catalin Roman, Peter J. Mccann
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Mobile computing is emerging as an important new paradigm which has the potential to reshape our thinking about distributed computation. Mobility has far-reaching implications on what designers and users can assume about communication patterns, resource availability, and applciation behaviors as components move from one location to another while joining or leaving groups of other components in their vicinity. New distributed algorithms are likely to be required as the nature of applications shifts with the emergence of this new kind of computing environment. Formal methods have an important role to play in the midst of these developments both in terms of …
A General Matrix Iterative Model For Dynamic Load Balancing, Mark A. Franklin, Vasudha Govindan
A General Matrix Iterative Model For Dynamic Load Balancing, Mark A. Franklin, Vasudha Govindan
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Effective load balancing algorithms are crucial in fully realizing the performance potential of parallel computer systems. This paper proposes a general matrix iterative model to represent a range of dynamic load balancing algorithms. The model and associated performance measures are used to evaluate and compare vairous load balancing algorithms and derive optimal algorithms and associated parameters for a given application and multiprocessor system. The model is parameterized to represent three load balancing algorithms - the random strategy, diffusion and complete redistribution algorithms. The model is validated by comparing the results with measured performance on a realistic workload. The parallel N-body …
A Survey Of Network Signaling, Dakang Wu
A Survey Of Network Signaling, Dakang Wu
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Abstract Network signaling is the process of transferring control information among components of a communication network to establish, maintain, and release connections, and to pass the network management information. The rapid evolution in the field of telecommunications has led to the rapid evolution of network signaling. In this paper, we review the evolution of network signaling. We emphasize the concepts and protocols used in modern fast packet switching networks especially in emerging ATM networks.
Distributed Radiological Multimedia Conferencing, Naeem Bari
Distributed Radiological Multimedia Conferencing, Naeem Bari
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Distributed Radiological Multimedia Conference (DRMC) is a collaborative imaging/multimedia conferencing tool which allows geographically separated physicians to confer over a shared projection radiograph. DRMC utilizes the advantages of high bandwidth and scalability offered by the new Asynchronous Transfer Mode (ATM) network technology. This application is customized for the high quality of displayed images and rapid response to user requests. It allows conferees to: share a common radiograph; each possess an independently controlled globally visible cursor; be able to point to and outline areas on the image to bring it to the other conferees' attention; and see and hear each other …
Load Balance Properties Of Distributed Data Layouts For Clustered Mod Servers, Milind M. Buddhikot, Guru Parulkar
Load Balance Properties Of Distributed Data Layouts For Clustered Mod Servers, Milind M. Buddhikot, Guru Parulkar
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Large scale storage servers that provide location transparent, interactive access to hundreds or thousands of concurrent, independent clients will be important components of hte furture information super-highway infrastructure. Two key requirements of such servers are as follows: support high parallelism and concurrency in data access to allow large number of access to the same or different data. Second, support independent interactive playout control operations such as fast-forward, rewind, slow-play, pause, resume, random access etc. with minimal latency. This paper assumes a distributed storage server architecture consisting of several high performance storage nodes interconnected by a high speed desk area network …
Reliable Fifo Load Balancing Over Multiple Fifo Channels, Hari Adieseshu, Gurudatta M. Parulkar, George Varghese
Reliable Fifo Load Balancing Over Multiple Fifo Channels, Hari Adieseshu, Gurudatta M. Parulkar, George Varghese
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Link striping algorithms are often used to overcome transmission bottlenecks in computer networks. However, traidtional striping algorithms suffer from two major disadvantages. They provide inadequate load sharing in the presence of variable length packets, and may result in non-FIFO delivery of data. We describe a new family of link striping algorithms that solve both problems. Our scheme applies to packets at any layer (physical, data, link, network, and transport) that work over multiple FIFO channels. We deal with variable sized packets by showing how a class of fair queueing algorithms can be converted into load sharing algorithms. Our transformation results …
An Interactive Model Of Teaching, H. David Mathias
An Interactive Model Of Teaching, H. David Mathias
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Previous teaching models in the learning theory community have been batch models. That is, in these models the teacher has generated a single set of helpful examples to present to the learner. In this paper we present an interactive model in which the learner has the ability to ask queries as in the query learning model of Angluin [1]. We show that this model is at least as powerful as previous teaching models. We also show that anything learnable with queries, even by a randomized learner, is teachable in our model. In all previous teaching models, all classes shown to …
Self-Stabilization By Window Washing, Adam M. Costello, George Varghese
Self-Stabilization By Window Washing, Adam M. Costello, George Varghese
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A useful way to design simple and robust protocols is to make them self-stabilitizing. We describe a new general technique for self-stabilization called window washing. We apply this technique to generalized sliding window protocols that work on a number of topologies. This results in simple, efficient, and self-stabilizing protocols. As far as we know, both window washing and generalized sliding window protocols are new ideas. Our protocols can be used for data links, reliable broadcast, and flow control.
Assertional Reasoning About Pairwise Transient Interactions In Mobile Computing, Gruia-Catalin Roman, Peter J. Mccann, Jerome Plun
Assertional Reasoning About Pairwise Transient Interactions In Mobile Computing, Gruia-Catalin Roman, Peter J. Mccann, Jerome Plun
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Mobile computing represents a major point of departure from the traditional distributed computing paradigm. The potentially very large number of independent computing units, a decoupled computing style, frequent disconnections, continuous position changes, and the location-dependent nature of the behavior and communication patterns of the individual components present designers with unprecedented challenges in the areas of modularity and dependability. This paper describes two ideas regarding a modular approach to specifying and reasoning about mobile computing. The novelty of our approach rests with the notion of allowing transient interactions among programs which mobe in space. In this paper we restrict our concert …