Complexity of analyzing the synchronization structure of concurrent programs
SummaryFoundational to verification of some aspects of communicating concurrent systems is knowledge of the synchronization which may occur during execution. The synchronization determines the actions that may occur in parallel, may determine program data flow, and may also lead to inherently erroneous situations (e.g. deadlock). This paper formalizes the notion of the synchronization structure of concurrent programs that use the rendezvous (or similar) mechanism for achieving synchronization. The formalism is oriented towards supporting verification as performed by automated static program analysis. Complexity results are presented which indicate what may be expected in this area and which also shed light on the difficulty of correctly constructing concurrent systems. Specifically, most of the analysis tasks considered are shown to be intractable.

title: A Component- and Message-Based Architectural Style for GUI Software

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: 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: 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: Advanced workflow management technologies
abstract: manrand r rackSummary Process, workflow, and groupware projects both in the commercial research worlds have each approached the problem of human communication and dination with different sets of tools and technologies implemented from different pe spectives. Activity dependencies and the philosophical assumptions about how wo performed are managed differently in each discipline. While most of these tools re sent promising approaches, they have yet to be widely adopted, particularly in the of increased usage of online information through the WWW and computer network Electronic information coming to the individual and into the corporation is becomin increasingly unmanageable. People are able to create information regardless of th location or method of access due to increasing mobility and interoperability of the t they use. Because of the common concerns, trends are moving towards overlap an vergence of requirements. However, these communities have yet to identify the uni cross-discipline requirements for a supporting technical infrastructure addressing t level of flexibility, scalability, and support for evolution over time required in these re world settings. This paper surveys the current approaches to project communicatio coordination, details the range of requirements across several related disciplines, identifies various tradeoffs and trends which may effect the adoption, design, and e tion of an advanced technical workflow infrastructure.

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.

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: Authenticating Pollock paintings using fractal geometry
abstract: Jackson Pollock's paintings are currently valued up to US$75M, triggering discussions that attributation procedures featuring subjective visual assessments should be complimented by quantitative scientific procedures. We present a fractal analysis of Pollock's patterns and discuss its potential for authenticity research.

title: Comparison of conformer distributions in the crystalline state with conformational energies calculated by ab initio techniques
abstract: SummaryThe conformational preferences of 12 molecular substructures in the crystalline state have been determined and compared with those predicted for relevant model compounds by ab initio molecular orbital calculations. Least-squares regression shows that there is a statistically significant correlation between the crystal-structure conformer distributions and the calculated potential-energy differences, even though the calculations relate to a gas-phase environment. Torsion angles associated with high strain energy (>1 kcal mol-1) appear to be very unusual in crystal structures and, in general, high-energy conformers are underrepresented in crystal structures compared with a gas-phase, room-temperature Boltzmann distribution. It is concluded that crystal packing effects rarely have a strong systematic effect on molecular conformations. Therefore, the conformational distribution of a molecular substructure in a series of related crystal structures is likely to be a good guide to the corresponding gas-phase potential energy surface.

title: Using Music to Interact with a Virtual Character
abstract: We present a real-time system which allows musicians to interact with synthetic virtual characters as they perform. Using Max/MSP to parameterize keyboard and vocal input, meaningful features (pitch, amplitude, chord information, and vocal timbre) are extracted from live performance in real-time. These extracted musical features are then mapped to character behaviour in such a way that the musician's performance elicits a response from the virtual character. The system uses the ANIMUS framework to generate believable character expressions. Experimental results are presented for simple characters.