Showing papers on "Systems architecture published in 1996"

Dynamic structure in software architectures

Abstract: Much of the recent work on Architecture Description Languages (ADL) has concentrated on specifying organisations of components and connectors which are static When the ADL specification is used to drive system construction, then the structure of the resulting system in terms of its component instances and their interconnection is fixed This paper examines ADL features which permit the description of dynamic software architectures in which the organisation of components and connectors may change during system executionThe paper outlines examples of language features which support dynamic structure These examples are taken from Darwin, a language used to describe distributed system structure An operational semantics for these features is presented in the π-calculus, together with a discussion of their advantages and limitations The paper discusses some general approaches to dynamic architecture description suggested by these examples

Multimedia collaboration system with separate data network and A/V network controlled by information transmitting on the data network

Abstract: A multimedia collaboration system that integrates separate real-time and asynchronous networks--the former for real-time audio and video, and the latter for control signals and textual, graphical and other data--in a manner that is interoperable across different computer and network operating system platforms and which closely approximates the experience of face-to-face collaboration, while liberating the participants from the limitations of time and distance. These capabilities are achieved by exploiting a variety of hardware, software and networking technologies in a manner that preserves the quality and integrity of audio/video/data and other multimedia information, even after wide area transmission, and at a significantly reduced networking cost as compared to what would be required by presently known approaches. The system architecture is readily scalable to the largest enterprise network environments. It accommodates differing levels of collaborative capabilities available to individual users and permits high-quality audio and video capabilities to be readily superimposed onto existing personal computers and workstations and their interconnecting LANs and WANs. In a particular preferred embodiment, a plurality of geographically dispersed multimedia LANs are interconnected by a WAN. The demands made on the WAN are significantly reduced by employing multi-hopping techniques, including dynamically avoiding the unnecessary decompression of data at intermediate hops, and exploiting video mosaicing, cut-and-paste and audio mixing technologies so that significantly fewer wide area transmission paths are required while maintaining the high quality of the transmitted audio/video.

Adapting to network and client variability via on-demand dynamic distillation

Abstract: The explosive growth of the Internet and the proliferation of smart cellular phones and handheld wireless devices is widening an already large gap between Internet clients. Clients vary in their hardware resources, software sophistication, and quality of connectivity, yet server support for client variation ranges from relatively poor to none at all. In this paper we introduce some design principles that we believe are fundamental to providing "meaningful" Internet access for the entire range of clients. In particular, we show how to perform on-demand datatype-specific lossy compression on semantically typed data, tailoring content to the specific constraints of the client. We instantiate our design principles in a proxy architecture that further exploits typed data to enable application-level management of scarce network resources. Our proxy architecture generalizes previous work addressing all three aspects of client variation by applying well-understood techniques in a novel way, resulting in quantitatively better end-to-end performance, higher quality display output, and new capabilities for low-end clients.

Predictive system shutdown and other architectural techniques for energy efficient programmable computation

Abstract: With the popularity of portable devices such as personal digital assistants and personal communicators, as well as with increasing awareness of the economic and environmental costs of power consumption by desktop computers, energy efficiency has emerged as an important issue in the design of electronic systems. While power efficient ASIC's with dedicated architectures have addressed the energy efficiency issue for niche applications such as DSP, much of the computation continues to be implemented as software running on programmable processors such as microprocessors, microcontrollers, and programmable DSP's. Not only is this true for general purpose computation on personal computers and workstations, but also for portable devices, application-specific systems etc. In fact, firmware and embedded software executing on RISC and DSP processor cores that are embedded in ASIC's has emerged as a leading implementation methodology for speech coding, modem functionality, video compression, communication protocol processing etc. This paper describes architectural techniques for energy efficient implementation of programmable computation, particularly focussing on the computation needed in portable devices where event-driven user interfaces, communication protocols, and signal processing play a dominant role. Two key approaches described here are predictive system shutdown and extended voltage scaling. Results indicate that a large reduction in power consumption can be achieved over current day solutions with little or no loss in system performance.

A survey of architecture description languages

Abstract: Architecture Description Languages (ADLs) are emerging as viable tools for formally representing the architectures of systems. While growing in number, they vary widely in terms of the abstractions they support and analysis capabilities they provide. Further, many languages not originally designed as ADLs serve reasonably well at representing and analyzing software architectures. This paper summarizes a taxonomic survey of ADLs that is in progress. The survey characterizes ADLs in terms of (a) the classes of systems they support; (b) the inherent properties of the languages themselves; and (c) the process and technology support they provide to represent, refine, analyze, and build systems from an architecture. Preliminary results allow us to draw conclusions about what constitutes an ADL, and how contemporary ADLs differ from each other.

Coordination of Multiple Intelligent Software Agents

Abstract: We are investigating techniques for developing distributed and adaptive collections of information agents that coordinate to retrieve, filter and fuse information relevant to the user, task and situation, as well as anticipate user's information needs. In our system of agents, information gathering is seamlessly integrated with decision support. The task for which particular information is requested of the agents does not remain in the user's head but it is explicitly represented and supported through agent collaboration. In this paper we present the distributed system architecture, agent collaboration interactions, and a reusable set of software components for structuring agents. The system architecture has three types of agents: Interface agents interact with the user receiving user specifications and delivering results. They acquire, model, and utilize user preferences to guide system coordination in support of the user's tasks. Task agents help users perform tasks by formulating problem solving plans and carrying out these plans through querying and exchanging information with other software agents. Information agents provide intelligent access to a heterogeneous collection of information sources. We have implemented this system framework and are developing collaborating agents in diverse complex real world tasks, such as organizational decision making, investment counseling, health care and electronic commerce.

ARM System Architecture

Abstract: From the Publisher: Features allows the reader to get started with the ARM chip and get programs running under emulation discusses assembly level programming, particularly for the ARM provides information on general computer architecture (processor design, caches, memory management) with detailed illustrations based on ARM chips details the architecture development process covers embedded system design principles and case studies

System for teleconferencing in which collaboration types and participants by names or icons are selected by a participant of the teleconference

Abstract: A multimedia collaboration system that integrates separate real-time and asynchronous networks--the former for real-time audio and video, and the latter for control signals and textual, graphical and other data--in a manner that is interoperable across different computer and network operating system platforms and which closely approximates the experience of face-to-face collaboration, while liberating the participants from the limitations of time and distance. These capabilities are achieved by exploiting a variety of hardware, software and networking technologies in a manner that preserves the quality and integrity of audio/video/data and other multimedia information, even after wide area transmission, and at a significantly reduced networking cost as compared to what would be required by presently known approaches. The system architecture is readily scalable to the largest enterprise network environments. It accommodates differing levels of collaborative capabilities available to individual users and permits high-quality audio and video capabilities to be readily superimposed onto existing personal computers and workstations and their interconnecting LANs and WANs. In a particular preferred embodiment, a plurality of geographically dispersed multimedia LANs are interconnected by a WAN. The demands made on the WAN are significantly reduced by employing multi-hopping techniques, including dynamically avoiding the unnecessary decompression of data at intermediate hops, and exploiting video mosaicing, cut-and-paste and audio mixing technologies so that significantly fewer wide area transmission paths are required while maintaining the high quality of the transmitted audio/video.

System for providing a directory of AV devices and capabilities and call processing such that each participant participates to the extent of capabilities available

Abstract: A multimedia collaboration system that integrates separate real-time and asynchronous networks--the former for real-time audio and video, and the latter for control signals and textual, graphical and other data--in a manner that is interoperable across different computer and network operating system platforms and which closely approximates the experience of face-to-face collaboration, while liberating the participants from the limitations of time and distance. These capabilities are achieved by exploiting a variety of hardware, software and networking technologies in a manner that preserves the quality and integrity of audio/video/data and other multimedia information, even after wide area transmission, and at a significantly reduced networking cost as compared to what would be required by presently known approaches. The system architecture is readily scalable to the largest enterprise network environments. It accommodates differing levels of collaborative capabilities available to individual users and permits high-quality audio and video capabilities to be readily superimposed onto existing personal computers and workstations and their interconnecting LANs and WANs. In a particular preferred embodiment, a plurality of geographically dispersed multimedia LANs are interconnected by a WAN. The demands made on the WAN are significantly reduced by employing multi-hopping techniques, including dynamically avoiding the unnecessary decompression of data at intermediate hops, and exploiting video mosaicing, cut-and-paste and audio mixing technologies so that significantly fewer wide area transmission paths are required while maintaining the high quality of the transmitted audio/video.

Distributed interactive multimedia system architecture

Abstract: Various aspects of an interactive multimedia system and associated methods. In general, the multimedia system employs central and peripheral hubs that function to provide services to a plurality of clients of a call manager server, or manager subsystem. The hubs and subsystem cooperate to serve requests originating in the plurality of clients. The client-server-client architecture allows for distributed processing and resource management. Redundant connections between the various network subsystems and hubs provide survivability. Each subsystem or hub is provided with the ability to initialize or recover from systemic errors, thereby distributing initialization and recovery. Certain of the distributed resources are capable of being managed from other subsystems, thereby allowing sharing of the resources. An open numbering plan allows efficient call treatment of dialed numbers. Call processing is sharable between multiple manager subsystems. Finally, an iterative process is employed to ensure that calls routed through the network travel the shortest possible path.

ATLAS: an infrastructure for global computing

Abstract: In this paper, we present a proposed system architecture for global computing that we call ATLAS, and we describe an early prototype that implements several of the mechanisms and policies that comprise the proposed architecture. ATLAS is designed to execute parallel multithreaded programs on the networked computing resources of the world. The ATLAS system is a marriage of existing technologies from Java and Cilk together with some new technologies needed to extend the system into the global domain.

A fuzzy-logic architecture for autonomous multisensor data fusion

Abstract: Fuzzy logic techniques have become popular to address various processes for multisensor data fusion. Examples include the following: (1) fuzzy membership functions for data association; (2) evaluation of alternative hypotheses in multiple hypothesis trackers; (3) fuzzy-logic-based pattern recognition (e.g., for feature-based object identification); and (4) fuzzy inference schemes for sensor resource allocation. These approaches have been individually successful but are limited to only a single subprocess within a data fusion system. At The Pennsylvania State University, Applied Research Laboratory, a general-purpose fuzzy-logic architecture has been developed that provides for control of sensing resources, fusion of data for tracking, automatic object recognition, control of system resources and elements, and automated situation assessment. This general architecture has been applied to implement an autonomous vehicle capable of self-direction, obstacle avoidance, and mission completion. The fuzzy logic architecture provides interpretation and fusion of multisensor data (i.e., perception) as well as logic for process control (action). This paper provides an overview of the fuzzy-logic architecture and a discussion of its application to data fusion in the context of the Department of Defense (DoD) Joint Directors of Laboratories (JDL) Data Fusion Process Model. A new, robust, fuzzy calculus is introduced. An application example is provided.

Synchronization in video conferencing

Abstract: A multimedia collaboration system that integrates separate real-time and asynchronous networks--the former for real-time audio and video, and the latter for control signals and textual, graphical and other data--in a manner that is interoperable across different computer and network operating system platforms and which closely approximates the experience of face-to-face collaboration, while liberating the participants from the limitations of time and distance. These capabilities are achieved by exploiting a variety of hardware, software and networking technologies in a manner that preserves the quality and integrity of audio/video/data and other multimedia information, even after wide area transmission, and at a significantly reduced networking cost as compared to what would be required by presently known approaches. The system architecture is readily scalable to the largest enterprise network environments. It accommodates differing levels of collaborative capabilities available to individual users and permits high-quality audio and video capabilities to be readily superimposed onto existing personal computers and workstations and their interconnecting LANs and WANs. In a particular preferred embodiment, a plurality of geographically dispersed multimedia LANs are interconnected by a WAN. The demands made on the WAN are significantly reduced by employing multi-hopping techniques, including dynamically avoiding the unnecessary decompression of data at intermediate hops, and exploiting video mosaicing, cut-and-paste and audio mixing technologies so that significantly fewer wide area transmission paths are required while maintaining the high quality of the transmitted audio/video.

An overview of the Rialto real-time architecture

Abstract: The goal of the Rialto project at Microsoft Research is to build a system architecture supporting coexisting independent real-time (and non-real-time) programs. Unlike traditional embedded-systems real-time environments, where timing and resource analysis among competing tasks can be done off-line, it is our goal to allow multiple independently authored real-time applications with varying timing and resource requirements to dynamically coexist and cooperate to share the limited physical resources available to them, as well as also coexisting with non-real-time applications.This paper gives an overview of the Rialto real-time architecture as it is implemented today and reports on some of the early results obtained. In particular, it describes the use of time constraints, activities, CPU and other resource reservation, and the system resource planner, and how they work together to achieve our goal of providing a flexible, dynamic real-time computing environment.

A Sentinel Approach to Fault Handling in Multi-Agent Systems

Abstract: Fault handling in Multi-Agent Systems (MAS) is not much addressed in current research. Normally, it is considered difficult to address in detail and often well covered by traditional methods, relying on the underlying communication and operating system. In this paper it is shown that this is not necessarily true, at least not with the assumptions on applications we have made. These assumptions are a massive distribution of computing components, a heterogeneous underlying infrastructure (in terms of hardware, software and communication methods), an emerging configuration, possibly different parties in control of sub-systems, and real-time demands in parts of the system.

L-ALLIANCE: Task-oriented multi-robot learning in behavior-based systems

Abstract: A large application domain for multi-robot teams involves task-oriented missions, in which potentially heterogeneous robots must solve several distinct tasks. Previous research addressing this problem in multi-robot systems has largely focused on issues of efficiency, while ignoring the real-world situated robot needs of fault tolerance and adaptivity. This paper addresses this problem by developing an architecture called L-ALLIANCE that incorporates task-oriented action selection mechanisms into a behavior-based system, thus increasing the efficiency of robot team performance while maintaining the desirable characteristics of fault tolerance and adaptivity. We present our investigations of several competing control strategies and derive an approach that works well in a wide variety of multi-robot task-oriented mission scenarios. We provide a formal model of this technique to illustrate how it can be incorporated into any behavior-based system.

A Two Layer Case-Based Reasoning Architecture for Medical Image Understanding

Abstract: The paper describes a novel architecture for image understanding It is based on acquisition of radiologist knowledge, and combines low-level structure analysis with high-level interpretation of image content, within a task-oriented model A case based reasoner working on a segment case-base contains the individual image segments These cases with labels are considered indexes for another case based reasoner working on an organ interpretation case base Both are Creek type case based reasoners, here operating within a propose-critique-modify task structure Methods for criticizing suggested interpretations by way of explanation, and how interpretations may be modified, are presented An example run illustrates the system architecture and its key concepts

Spoken language systems : beyond prompt and response

Abstract: Spoken language systems allow users to interact with computers by speaking to them. This paper focuses on the most advanced systems, which seek to allow as natural a style of interaction as possible. Specifically this means the use of continuous speech recognition - natural language understanding to interpret the utterance, and an intelligent dialogue manager which allows a flexible style of 'conversation' between computer and user. This paper discusses the architecture of spoken language systems and the components of which they are made, and describes both a variety of possible approaches and the particular design decisions made in some systems developed at BT Laboratories. Three spoken language systems in the course of development are described - a multimodal interface to the BT Business Catalogue, an e-mail secretary which can be consulted over the telephone network, and a multimodal system to allow selection of films in the interactive TV environment.

Object-oriented graphic system with extensible damage repair and drawing constraints

Abstract: A method and apparatus for developing graphics applications, including a framework for handling the exchange of graphical data between applications and for presenting and manipulating graphical objects. The framework includes a number of classes which are used by the application developer to facilitate the interaction between the major subsystems, Models, Views and User Interface, of the system architecture.

Pan-browser support for annotations and other meta-information on the World Wide Web

Abstract: This paper describes an innovative approach for groups to create and share commentary about the content of documents accessible via the World Wide Web. In particular, the system described supports the creation, presentation, and control of user-created meta-information, which is displayed with the corresponding documents but stored separately from them. The typical use for this mechanism is to support annotations about documents accessed through browsing clients of the Web. In contrast to other approaches, the system described herein does not depend on changes in, or specializations to, Web browsers or servers. Rather, the system takes advantage of the notion of application-specific stream transducers ; most of the functionality of the system is provided by a specialized proxy. We describe design considerations, the system architecture, usage scenarios, our initial implementation, and future work.

An unified vehicle supervising and traffic information system

Abstract: An unified vehicle supervising and traffic information system architecture is proposed. This new architecture integrates different system functions such as digital mobile radio communication, vehicle monitoring, traffic information collection, dynamic route guidance, and automatic toll collection into a single system architecture. A vehicle communication and ranging system is the radio interface of the architecture. Packetized data transmission through this radio interface can be used to measure the received signal delay by pulse ranging. An uplink message from a vehicle containing vehicle speed information and the measured delay are both sent to a traffic control and information center for vehicle monitoring. The center estimates the vehicle location, and calculates the average traveling time and average congestion level for each road link accordingly. Vehicle monitoring information and the estimated traffic condition can be offered to either the public or dispatching centers. A toll collection center will be able to automatically charge a vehicle through the monitoring process. Furthermore, a vehicle will be able to access the traffic control and information center to obtain its own dynamic route guidance information, and each vehicle can be guided in such a way to optimize the overall road traffic. Finally, we suggest two methods which use the infrastructure of existing digital cellular systems (GSM and IS-95) to implement the proposed system architecture.

A framework for product data

Abstract: IT support for engineering involves the integration of existing, evolving and future product data, and software that processes that data. Thus, there is increasing interest in the representation of product data in the computer to support CAE applications. To avoid duplication and inconsistency, and to support the use of new implementation technology as it emerges, conceptual models of product data are required. Such models are independent of the software and hardware environments in which they are implemented. System architectures to support the integration of applications at implementation time are becoming an accepted part of engineering information systems. To use these software support environments effectively, integrated product data is required. It must also be possible to extend the integrated product data in a controlled fashion if it is to evolve to support future engineering applications effectively. A framework that is a part of the product data at the conceptual modeling stage helps to satisfy these requirements. The framework presented is a structure for the information content of product data rather than for the implementation of such data. Product data based on the framework can be successfully implemented in a number of different database forms. This paper describes a framework for electromechanical product data that has been implemented in a structure editor and is being used to support a range of engineering applications. The process of product data integration can be improved by using existing integration strategies together with a framework that provides an overall organization for the data.

Lightweight structural summarization as an aid to software evolution

Abstract: To effectively perform a change to an existing software system, a software engineer needs to have some understanding of the structure of the system. All too often, though, an engineer must proceed to change a system without sufficient structural information because existing software understanding techniques are unable to help the engineer acquire the desired knowledge within the time and cost constraints specified for the task. The thesis of this research is that an approach based on summarization can overcome the limitations associated with existing approaches, enabling an engineer to assess, plan, and execute changes to a software system more effectively. Summarization involves the production of overviews of vast amounts of user-selected information in a timely manner. I describe two techniques developed to support the summarization approach. The first technique, the software reflexion model technique, enables an engineer to summarize selected structural information in the context of a task-specific high-level model. The second technique, the lexical source model extraction technique, supports the summarization process by facilitating the scanning and analysis of system artifacts for structural information that is difficult or impossible to extract at low cost using existing approaches. Each of these techniques is lightweight and iterative: the engineer is able to quickly and easily gain access to partial and approximate structural information, and may then balance the completeness and accuracy of the information needed with the cost of further applying the technique. I demonstrate the viability of the approach by describing its use on a variety of change tasks and systems, including the use of the reflexion model technique by an engineer at Microsoft Corporation to aid with an experimental reengineering of the million-line Excel spreadsheet product.

Rapide: A language and toolset for simulation of distributed systems by partial orderings of events.

Abstract: This paper describes the RAPIDE concepts of system architecture, causal event simulation, and some of the tools for viewing and analysis of causal event simulations. Illustration of the language and tools is given by a detailed small example.

A hospital integrated framework for multimodality image base management

Abstract: The trend in healthcare information technology is increasingly digital and multimedia oriented. The next generation of health care information systems will consist of a vast network of heterogeneous, autonomous, and distributed imaging scanners, databases, information systems, knowledge intensive applications, and large quantities of multimedia medical data. A key challenge facing system researchers and builders is to provide a new organizational framework that can integrate this varied collection of resources into what appears to be a uniform and logical conglomeration of data and knowledge store in order to increase the availability of global or previously nonaccessible information and to address demanding new information processing requirements for diverse image-assisted medical applications. The purpose of this paper is to present the authors' research toward the development of a hospital integrated framework of multimodality image base management (MIBM) for digital radiology of the future. This evolutionary framework consists of three hierarchical components: a hospital-integrated picture archiving and communication system (HI-PACS), a medical image database system (MIDS), and a set of image-based medical applications that relies on the support of MIDS and PACS. In this paper, the authors describe the system architecture, guiding principles, and design specifications of HI-PACS and MIDS and illustrate their functions and capabilities with three implemented applications, namely, patient folder workflow, distributed object management, and multimodality imaging studies. In addition, the authors conclude their findings with a summary of challenges and research directions.

Industrial Robot Programming

Abstract: Industrial robots play a key role in manufacturing systems. Robots are distinguished from other types of machinery mainly on the basis of their programmability and ability to be adaptable to different tasks. The use of computer control to achieve desired flexibility implies that software issues for embedded control systems are central for the applicability and utilization of the equipment. The structure of control systems today, however, limits the applicability of robots, thus leaving many human unfriendly operations to be performed manually. This thesis takes a problem oriented approach, without enforcing use of formal methods. Considering industrial demands, such as computing efficiency and simple factory-floor operation, a layered system architecture and technical solutions to accomplish it are proposed. A notion of user views is introduced as the basis for definition of the layers; the layers support programming on levels ranging from implementation of motor control and up to end-user programming. An experimental platform, built around industrially available robots, has been developed. Specially developed hardware interfaces and reconfigurations of the original (ABB) system permits control and programming even of the low level motion control. Run-time efficiency within the proposed open and layered system was achieved by a new concept called actions. Actions are pieces of compiled code that, by use of certain compiling and linking techniques, can be passed as parameters between the layers. The required interplay between application specific programs and built-in motion control could therefore be accomplished. A number of case studies and results from ongoing experimental evaluation indicate that the proposed control system principles are very useful also in an industrial context.

Object-oriented technology for real-time systems

Abstract: 1. Introduction. Real-time Systems. Object-Oriented Methods. Concurrency in a Real- time System. Object-Oriented Concurrency Models. Levels of Concurrency. Design Criteria of OCTOPUS. Introduction to Case Studies. 2. Overvoew of the Octopus Method. Roadmap and Structuring the Development Process. System Requirements Phase. System Architecture Phase. Subsystem Analysis Phase. Subsystem Design Phase. Subsystem Implementation Phase. 3. Requirements Specification. Use Cases. Use Case Diagram. System Context Diagram. 4. System Architecture. Modular Structure. Early Division into Subsystems. Subsystems Diagram. Incremental Development. Interfaces. Example. 5. Analysis Phase. Object Model. Functional Model. Dynamic Model. Analysis of the Hardware Wrapper. Summary. 6. Design Phase. Design Objects. Interaction of Objects. Class Outlines. Design of Concurrency. Outlines of Processes and Messages. Design of the Hardware Wrapper. Summary. 7. Process Priorities and Timing. Basic Concepts. Deriving Process Priorities. Timing and Concurrency Behavior. 8. Transition from Design to Implementation. C++ and C Interpretability. Member Access Control. Visibility. Memory and Performance Optimization. Synchronization. Implementing Statecharts. Constructing Global Objects. Development Environment. 9. Case Study: Subscriber Line Tester. System Requirements Specification. SLT Application Subsystem Analysis. SLT Application Subsystem Design. Exercise: Hardware Wrapper. 10. Case Study: Cruise Control. Recapped System Requirements Specification. Application Subsystem Analysis. Analysis and Design of the Hardware Wrapper. Design of Application Subsystem. 11. Referemce Manual. Notation Summary. Case Tools. OCTOPUS Roadmap. References. Glossary. Index.