Chimera: hypertext for heterogeneous software environments
Emerging software development environments are characterized by heterogeneity: they are composed of diverse object stores, user interfaces, and tools. This paper presents an approach for providing hypertext services in this heterogeneous setting. Central notions of the approach include the following. Anchors are established with respect to interactive views of objects, rather than the objects themselves. Composable, n-ary links can be established between anchors on different views of objects stored in distinct object bases. Viewers (and objects) may be implemented in different programming languages afforded by a client-server architecture. Multiple, concurrently active viewers enable multimedia hypertext services. The paper describes the approach and presents an architecture which supports it. Experience with the Chimera prototype and its relationship to other systems is described.

title: On the role of software architectures in runtime system reconfiguration
abstract: Society's increasing dependence on software-intensive systems is driving the need for dependable, robust, continuously available systems. Runtime system reconfiguration is one aspect of achieving continuous availability. We present an architecture-based approach to runtime software reconfiguration, highlighting the beneficial role of architectural styles and software connectors in facilitating runtime change. We conclude by describing the implementation of our tool suite, called ArchStudio, that supports runtime reconfiguration using our architecture-based approach.

title: Reuse of off-the-shelf components in C2-style architectures
abstract: Reuse of large-grain software components offers the potential for significant savings in application development cost and time. Successful component reuse and substitutability depends both on qualities of the components reused as well as the software context in which the reuse is attempted. Disciplined approaches to the structure and design of software applications offers the potential of providing a hospitable setting for such reuse. We present the results of a series of exercises designed to determine how well “offthe-shelf” components could be reused in applications designed in accordance with the C2 software architectural style. The exercises involved the reuse of two user-interface constraint solvers, two graphics toolkits, a World Wide Web browser, and a persistent object manager. A subset of these components was used to construct numerous variations of a single application (thus an application family). The exercises also included construction of a simple development environment for locating and downloading a component off the Web and incorporating it into an application. The paper summarizes the style rules that facilitate reuse and presents the results from the exercises. The exercises were successful in a variety of dimensions; one conclusion is that the C2 style offers significant reuse potential to application developers. At the same time, wider trials and additional tool support are needed.1 Index Terms -software reuse, architectural styles, messagebased architectures, component-based development, graphical user interfaces (GUI).

title: Anomaly Detection in Concurrent Software by Static Data Flow Analysis
abstract: Algorithms are presented for detecting errors and anomalies in programs which use synchronization constructs to implement concurrency. The algorithms employ data flow analysis techniques. First used in compiler object code optimization, the techniques have more recently been used in the detection of variable usage errors in dngle process programs. By adapting these existing algorithms, the sane classes of variable usage errors can be detected in concurrent process programs. Important classes of errors unique to concurrent process programs are also described, and algorithms for their detection are presented.

title: Principled design of the modern Web architecture
abstract: The World Wide Web has succeeded in the large part because its software architecture has been designed to meet the needs of an Internet-scale distributed hypermedia system. The modern Web architecture emphasizes scalability of component interactions, generality of interfaces, independent deployment of components, and intermediary components to reduce interaction latency, enforce security, and encapsulate legacy systems. We introduce the Representational State Transfer (REST) architectural style, developed as an abstract model of the Web architecture to guide our redesign and definition of the Hypertext Transfer Protocol and Uniform Resource Identifiers. We describe the software engineering principles guiding REST and the interaction constraints chosen to retain those principles, contrasting them to the constraints of other architectural styles. We then compare the abstract model to the currently deployed Web architecture in order to elicit mismatches between the existing protocols and the applications they are intended to support.

title: Architectural support for trust models in decentralized applications
abstract: Decentralized applications are composed of distributed entities that directly interact with each other and make local autonomous decisions in the absence of a centralized coordinating authority. Such decentralized applications, where entities can join and leave the system at any time, are particularly susceptible to the attacks of malicious entities. Each entity therefore requires protective measures to safeguard itself against these entities. Trust management solutions serve to provide effective protective measures against such malicious attacks. Trust relationships help an entity model and evaluate its confidence in other entities towards securing itself. Trust management is, thus, both an essential and intrinsic ingredient of decentralized applications. However, research in trust management has not focused on how trust models can be composed into a decentralized architecture. The PACE architectural style, described previously [21], provides structured and detailed guidance on the assimilation of trust models into a decentralized entity's architecture. In this paper, we describe our experiments with incorporating four different reputation-based trust models into a decentralized application using the PACE architectural style. Our observations lead us to conclude that PACE not only provides an effective and easy way to integrate trust management into decentralized applications, but also facilitates reuse while supporting different types of trust models. Additionally, PACE serves as a suitable platform to aid the evaluation and comparison of trust models in a fixed setting towards providing a way to choose an appropriate model for the setting.

title: A High-Performance Flexible Architecture for Cryptography
abstract: Cryptographic algorithms are more efficiently implemented in custom hardware than in software running on general-purpose processors. However, systems which use hardware implementations have significant drawbacks: they are unable to respond to flaws discovered in the implemented algorithm or to changes in standards. In this paper we show how reconfigurable computing offers high performance yet flexible solutions for cryptographic algorithms. We focus on PipeRench, a reconfigurable fabric that supports implementations which can yield better than custom-hardware performance and yet maintains all the flexibility of software based systems. PipeRench is a pipelined reconfigurable fabric which virtualizes hardware, enabling large circuits to be run on limited physical hardware. We present implementations for Crypton, IDEA, RC6, and Twofish on PipeRench and an extension of PipeRench, PipeRench+. We also describe how various proposed AES algorithms could be implemented on PipeRench. PipeRench achieves speedups of between 2x and 12x over conventional processors.

title: Interference-Free Insertion of a Solid Body Into a Cavity: An Algorithm and a Medical Application
abstract: This article presents a novel algorithm for efficiently computing an interference-free insertion path of a body into a cavity and shows its practical use in the insertability analysis of custom orthopedic hip implants. The algorithm is designed to handle tightly fit, very complex three-dimensional bodies requiring fine, complex, coupled six-degree-of-freedom motions in a preferred direction. It provides a practical method for efficiently handling the geometric complexity of tight-fit insertions. The algorithm computes an insertion path consisting of small interference-free body motion steps. It formulates local, linearized configuration space constraints derived from the shapes and computes suc cessive motion steps by solving a series of linear optimization problems whose solution corresponds to the maximum allowed displacement in a preferred direction satisfying the constraints. It either finds a successful insertion path or a stuck conftgura tion. We demonstrate the algorithm with EXTRACT, a program for analyzing the insertability of cementless custom orthopedic hip implants. EXTRACT computes interference-free insertion paths for tightly fit implant and canal shapes described with 10,000 facets to an accuracy of 0.01 inch in 30 minutes on a workstation. It has been successfully tested on 30 real cases provided by a medical equipment manufacturer.

title: Deep Surrender: Musically Controlled Responsive Video
abstract: In this paper we describe our responsive video performance, Deep Surrender, created using Cycling ’74’s Max/MSP and Jitter packages. Video parameters are manipulated in real-time, using chroma-keying and colour balance modification techniques to visualize the keyboard playing and vocal timbre of a live performer. We present the musical feature extraction process used to create a control system for the production, describe the mapping between audio and visual parameters, and discuss the artistic motivations behind the piece.

title: Visualizing Emotion in Musical Performance Using a Virtual Character
abstract: We describe an immersive music visualization application which enables interaction between a live musician and a responsive virtual character. The character reacts to live performance in such a way that it appears to be experiencing an emotional response to the music it ‘hears.' We modify an existing tonal music encoding strategy in order to define how the character perceives and organizes musical information. We reference existing research correlating musical structures and composers' emotional intention in order to simulate cognitive processes capable of inferring emotional meaning from music. The ANIMUS framework is used to define a synthetic character who visualizes its perception and cognition of musical input by exhibiting responsive behaviour expressed through animation.

title: Multi-modal Interface for Fluid Dynamics Simulations Using 3-D Localized Sound
abstract: Multi-modal capabilities can be added to a simulation system in order to enhance data comprehension. We describe a system for adding sonification capabilities to a real-time computational fluid dynamics (CFD) simulator. Our system uses Max/MSP modules to add sonic properties to CFD solutions. The enhancements described in this paper allow users to locate sound sources in a 3---D environment using stereo auditory cues to identify data features.