1515021
Using style to understand descriptions of software architecture
The software architecture of most systems is described informally and diagrammatically. In order for these descriptions to be meaningful at all, figures are understood by interpreting the boxes and lines in specific, conventionalized ways[5]. The imprecision of these interpretations has a number of limitations. In this paper we consider these conventionalized interpretations as architectural styles and provide a formal framework for their uniform definition. In addition to providing a template for precisely defining new architectural styles, this framework allows for the proof that the notational constraints on a style are sufficient to guarantee the meanings of all described systems and provides a unified semantic base through which different stylistic interpretations can be compared.
326385
A formal basis for architectural connection
As software systems become more complex, the overall system structure—or software architecture—becomes a central design problem. An important step toward an engineering discipline of software is a formal basis for describing and analyzing these designs. In the article we present a formal approach to one aspect of architectural design: the interactions among components. The key idea is to define architectural connectors as explicit semantic entities. These are specified as a collection of protocols that characterize each of the participant roles in an interaction and how these roles interact. We illustrate how this scheme can be used to define a variety of common architectural connectors. We further provide a formal semantics and show how this leads to a system in which architectural compatibility can be checked in a way analogous to type-checking in programming languages.
12180900
Towards Formalized Software Architectures
An important goal in software engineering is to describe complex software systems at an architectural level of abstraction. While there are many useful architectural paradigms (pipes, blackboards, etc.) they are typically understood only idiomatically and applied in an ad hoc fashion. We show how a formal model allows us to say precisely what we mean by a software architecture, explore its properties, and systematically describe instances of the architecture. We illustrate the approach using the well-known example of pipe-filter architectures.
7706135
A case study in architectural modeling: the AEGIS system
Software architecture is receiving increasingly attention as a critical design level for software systems. However the current practice of architectural description is largely informal and ad hoc, with the consequence that architectural documents serve as a poor communication mechanism, are difficult to analyze, and may have very little relationship to the implemented system. In an attempt to address these problems several researchers have experimented with formalisms for architectural specification and modelling. One such formalism is the WRIGHT specification language. In this paper, we show how WRIGHT can be used to provide insight into an architectural design by modelling a prototype implementation of part of the AEGIS Weapons System (AWS).
11583473
Architectural Mismatch: Why Reuse Is So Hard
Why isn't there more progress toward building systems from existing parts? One answer is that the assumptions of the parts about their intended environment are implicit and either don't match the actual environment or conflict with those of other parts. The authors explore these problems in the context of their own experience with a compositional approach. >
9208543
Formalizing Architectural Connection
As software systems become more complex the overall system structure { or software architecture { becomes a central design problem. An important step towards an engineering discipline of software is a formal basis for describing and analyzing these designs. In this paper we present a theory for one aspect of architectural description: the interactions between components. The key idea is to de ne architectural connectors as explicit semantic entities. These are specied as a collection of protocols that characterize each of the participant roles in an interaction and how these roles interact. We illustrate how this scheme can be used to de ne a variety of common architectural connectors. We provide a formal semantics and show how this leads to a sound deductive system in which architectural compatibility can be checked in a way analogous to type checking in programming languages.
17318100
Using an architecture description language for quantitative analysis of real-time systems
An architecture description language (ADL) specifies the structure of an overall system as an assembly of interacting components. ADLs can serve as input to a variety of development tools. We outline the Avionics Architecture Description Language, an emerging SAE standard for describing the architectures of hard real-time, safety-critical embedded computer systems. We describe a suite of tools that perform a set of verification, modeling and analysis, and implementation activities given an AADL specification. We summarize a study that applied these technologies using data about a complex avionics system, identifying and discussing some of the issues raised by this exercise.
19591181
RAVE: Real-Time Services for the Web
Abstract RAVE provides Web clients with real-time data services. Thus, RAVE supports live and stored video and audio as well as less typical real-time services such as MIDI and information services (e.g., news or stock market feeds). The system is extensible so that new real-time services can easily be added. RAVE has a flexible distribution architecture: it supports unicast and multicast, as well as both real-time data sources and sinks. RAVE integrates well into the Web so that many multimedia applications may be written using simple HTML extensions. We describe the RAVE architecture, the Web-client facilities that are required to support it, and three applications we have built using RAVE: a video library, a video mail system, and a video-conferencing tool.
33532247
Running an NSF REU program: observations, comments and suggestions
The Department of Computer Science at the University of Alabama, in conjunction with the National Science Foundation (NSF), offered a Research Experiences for Undergraduates (REU) program during the summer of 1991. This paper discusses the administration, structure, organization, and research efforts associated with this program.
6299292
Automated segmentation of lumbar vertebrae in digital videofluoroscopic images
Low back pain is a significant problem in the industrialized world. Diagnosis of the underlying causes can be extremely difficult. Since mechanical factors often play an important role, it can be helpful to study the motion of the spine. Digital videofluoroscopy has been developed for this study and it can provide image sequences with many frames, but which often suffer due to noise, exacerbated by the very low radiation dosage. Thus, determining vertebra position within the image sequence presents a considerable challenge. There have been many studies on vertebral image extraction, but problems of repeatability, occlusion and out-of-plane motion persist. In this paper, we show how the Hough transform (HT) can be used to solve these problems. Here, Fourier descriptors were used to describe the vertebral body shape. This description was incorporated within our HT algorithm from which we can obtain affine transform parameters, i.e., scale, rotation and center position. The method has been applied to images of a calibration model and to images from two sequences of moving human lumbar spines. The results show promise and potential for object extraction from poor quality images and that models of spinal movement can indeed be derived for clinical application.
11582167
Automated tracking in digitized videofluoroscopy sequences for spine kinematic analysis
Spine kinematic analysis provides useful information to aid understanding of the segmental motion of the vertebrae. Digitized videofluoroscopy (DVF) is the existing practical modality to image spine motion for kinematic data acquisition. However, obtaining kinematic parameters from DVF sequence requires manual landmarking which is a laborious process and can be subjective and error prone. This work develops an automated spine motion tracking algorithm for DVF sequences within a Bayesian framework. By utilizing the anatomical relationships between vertebrae, a dynamic Bayesian network with a particle filter at each node is constructed. The proposed algorithm overcomes the dimensionality problem in a regular particle filter and has more efficient and robust performance. It can provide results of about 1^o and 2pixels (0.2mm) variability in rotation and translation estimation, respectively, during repeated initialization analysis on sequences from simulation and in vivo healthy human subject studies.