12664895
Architectural Mismatch: Why Reuse Is Still So Hard
In this article, David Garlan, Robert Allen, and John Ockerbloom reflect on the state of architectural mismatch, a term they coined in their 1995 IEEE Software article, "Architectural Mismatch: Why Reuse Is So Hard." Although the nature of software systems has changed dramatically since the earlier article was published, the challenge of architectural mismatch remains an important concern for the software engineering field.
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.
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.
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).
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.
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.
8858476
A Parallel Algorithm for Graph Matching and Its MasPar Implementation
Search of discrete spaces is important in combinatorial optimization. Such problems arise in artificial intelligence, computer vision, operations research, and other areas. For realistic problems, the search spaces to be processed are usually huge, necessitating long computation times, pruning heuristics, or massively parallel processing. We present an algorithm that reduces the computation time for graph matching by employing both branch-and-bound pruning of the search tree and massively-parallel search of the as-yet-unpruned portions of the space. Most research on parallel search has assumed that a multiple-instruction-stream/multiple-data-stream (MIMD) parallel computer is available. Since massively parallel stream (SIMD) computers are much less expensive than MIMD systems with equal numbers of processors, the question arises as to whether SIMD systems can efficiently handle state-space search problems. We demonstrate that the answer is yes, and in particular, that graph matching has a natural and efficient implementation on SIMD machines.
44457281
An improved algorithm for relational distance graph matching
One of the problems in computer vision is to give a computer a representation of a scene and recognize the objects in the scene and their spatial relationships. This involves low-level vision (image processing), mid-level vision (feature extraction and measurement) and high-level vision (interpretation). One important part of high-level vision is relational matching, the process of matching two relational descriptions of objects, often for the purpose of object identification. This paper presents an improvement of the original method by Shapiro and Haralick for solving the relational distance graph matching problem for unlabeled graphs on a parallel computer.
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.
11904917
Neuro-fuzzy closed-loop control of depth of anaesthesia
The utility of the auditory evoked potential (AEP) is under investigation as a feedback signal for the automatic closed-loop control of general anaesthesia using neural networks and fuzzy logic. The AEP is a signal derived from the electroencephalogram (EEG) in response to auditory stimulation, which may be useful as an index of the 'depth' of anaesthesia. A simple back-propagation neural network can learn the AEP and provides a satisfactory input to a fuzzy logic infusion controller for the administration of anaesthetic drugs, but the problem remains that of reliable signal acquisition.