The design of a configurable and reconfigurable middleware platform

Summary. It is now well established that middleware platforms must accommodate an increasingly diverse range of requirements arising from the needs of both applications and underlying systems. Moreover, it is clear that to achieve this accommodation, platforms must be capable of both deployment-time configurability and run-time reconfigurability. This paper describes a middleware platform that addresses these requirements. The platform is built using a well-founded lightweight component model, uses reflective techniques to facilitate (re)configuration, and employs the notion of component frameworks to manage and constrain the scope of reconfiguration operations. Importantly, the platform also aims to achieve high performance and a level of standards conformance (e.g., with CORBA and COM). We demonstrate that, despite its high degree of configurability, the platform performs on a par with standard commercial CORBA ORBs. Received: April 2001 / Accepted: September 2001     

Software development for high-performance, reconfigurable, embedded multimedia systems

Reconfigurable platforms can be very effective for lowering production costs because they allow the reuse of architecture resources across a variety of applications. We show how to program a reduced-instruction-set-computing (RISC) microprocessor with a reconfigurable functional unit, focusing on DSP applications and using the example of a turbodecoder. We have developed a complete design flow, including a methodology and compilation tool chain, to address the instruction set hardware-software codesign problem for a processor with a runtime reconfigurable unit. The flow starts from a system-level specification (usually a software program) of the application and partitions it into software and hardware domains to achieve the best speed, power, and area performance, while satisfying resource constraints imposed by the target platform architecture. We describe a methodology and a set of tools that allow extensive design exploration for hardware-software codesign with the goal of improving the overall utilization of reconfigurable multimedia platforms.     

Pipelined parallelisation of automatic face inspection

A parallel pipeline is shown to be a natural method of speeding up a typical computer vision application, face inspection using `eigenfaces'. Faces within a stream of video images are continuously surveyed in a manner akin to a `conveyor belt' inspection process. The parallelisation is a new exemplar of a scheme for the rapid prototyping of large-scale, multi-algorithm applications suitable for transfer to a message-passing multicomputer. A general solution, pipelined processor farms, is preferred to a customised solution. This paper gives details of the software tools and software engineering methods employed to tackle this class of problem.     

Skeletons for parallel image processing: an overview of the SKIPPER project

This paper is a general overview of the S project, run at Blaise Pascal University between 1996 and 2002. The main goal of the S project was to demonstrate the applicability of skeleton-based parallel programming techniques to the fast prototyping of reactive vision applications. This project has produced several versions of a full-fledged integrated parallel programming environment (PPE). These PPEs have been used to implement realistic vision applications, such as road following or vehicle tracking for assisted driving, on embedded parallel platforms embarked on semi-autonomous vehicles. All versions of S share a common front-end and repertoire of skeletons––presented in previous papers––but differ in the techniques used for implementing skeletons. This paper focuses on these implementation issues, by making a comparative survey, according to a set of four criteria (efficiency, expressivity, portability, predictability), of these implementation techniques. It also gives an account of the lessons we have learned, both when dealing with these implementation issues and when using the resulting tools for prototyping vision applications.     

Comments on deriving protocol specifications from service specifications written in LOTOS

Summary. An algorithm by Kant, Higashino and Bochmann for service-based protocol synthesis in the standard specification language LOTOS is discussed. It is demonstrated that the transformations for distributed implementation of synchronised parallel execution and of disabling are not correct in a general case. Received: January 1998 / Accepted: January 1999     

A real-time vision module for interactive perceptual agents

Abstract. Interactive robotics demands real-time visual information about the environment. Real-time vision processing, however, places a heavy load on the robot's limited resources, which must accommodate multiple other processes running simultaneously. This paper describes a vision module capable of providing real-time information from ten or more operators while maintaining at least a 20-Hz frame rate and leaving sufficient processor time for a robot's other capabilities. The vision module uses a probabilistic scheduling algorithm to ensure both timely information flow and a fast frame capture. In addition, it tightly integrates the vision operators with control of a pan-tilt-zoom camera. The vision module makes its information available to other modules in the robot architecture through a shared memory structure. The information provided by the vision module includes the operator information along with a time stamp indicating information relevance. Because of this design, our robots are able to react in a timely manner to a wide variety of visual events.     

Using Handheld Devices in Synchronous Collaborative Scenarios

In this paper we present a platform specially designed for groupware applications running on handheld devices. Common groupware platforms request desktop computers as underlying hardware platforms. The fundamentally different nature of handheld devices has a great impact on the platform, e.g. resource limitations have to be considered, the network is slow and unstable. Often, personal data are stored on handheld devices, thus mechanisms have to ensure privacy. These considerations led to the QuickStep platform. Sample applications developed with QuickStep demonstrate the strengths of the QuickStep environment.     

A stereovision system for a planetary rover: calibration, correlation, registration, and fusion

This paper describes a complete stereovision system, which was originally developed for planetary applications, but can be used for other applications such as object modeling. A new effective on-site calibration technique has been developed, which can make use of the information from the surrounding environment as well as the information from the calibration apparatus. A correlation-based stereo algorithm is used, which can produce sufficient dense range maps with an algorithmic structure for fast implementations. A technique based on iterative closest-point matching has been developed for registration of successive depth maps and computation of the displacements between successive positions. A statistical method based on the distance distribution is integrated into this registration technique, which allows us to deal with such important problems as outliers, occlusion, appearance, and disappearance. Finally, the registered maps are expressed in the same coordinate system and are fused, erroneous data are eliminated through consistency checking, and a global digital elevation map is built incrementally.     

Analysis and verification of real-time systems using quantitative symbolic algorithms

The task of checking if a computer system satisfies its timing specifications is extremely important. These systems are often used in critical applications where failure to meet a deadline can have serious or even fatal consequences. This paper presents an efficient method for performing this verification task. In the proposed method a real-time system is modeled by a state-transition graph represented by binary decision diagrams. Efficient symbolic algorithms exhaustively explore the state space to determine whether the system satisfies a given specification. In addition, our approach computes quantitative timing information such as minimum and maximum time delays between given events. These results provide insight into the behavior of the system and assist in the determination of its temporal correctness. The technique evaluates how well the system works or how seriously it fails, as opposed to only whether it works or not. Based on these techniques a verification tool called Verus has been constructed. It has been used in the verification of several industrial real-time systems such as the robotics system described below. This demonstrates that the method proposed is efficient enough to be used in real-world designs. The examples verified show how the information produced can assist in designing more efficient and reliable real-time systems.     

Real-time CAM-based Hough transform algorithm and its performance evaluation

Abstract. This paper proposes a highly parallel Hough transform algorithm for real-time straight-line extraction and its hardware implementation on a content-addressable memory (CAM). To achieve high-speed processing, incrementation for voting, which composes the Hough transform, and calculations for coordinate updating are carried out for the every scan line, not every edge pixel, and extracting maxima in Hough space is executed by parallel comparing. Moreover, variously weighted voting achieves more accurate line extraction in spite of the quantization error and noise in the image space. In the implementation, the CAM acts as a PE (processing-element) array that effectively performs highly parallel processing for the Hough transform and also as a memory for two-dimensional Hough space, and both voting and peak extraction are directly executed by the CAM. Evaluations of CAM hardware size, processing time and the accuracy of line extraction show that a real-time and high-resolution Hough transform for a 256256 picture can be achieved using a single CAM chip with current VLSI technology. This CAM-based Hough transform algorithm promises to be an important step towards the realization of a real-time and compact image-understanding system. Received: 15 August 1998 / Accepted: 15 March 2000     

Making Workflow Change Acceptable

Virtual professional communities are supported by network information systems composed from standard Internet tools. To satisfy the interests of all community members, a user-driven approach to requirements engineering is proposed that produces not only meaningful but also acceptable specifications. This approach is especially suited for workflow systems that support partially structured, evolving work processes. To ensure the acceptability, social norms must guide the specification process. The RENISYS specification method is introduced, which facilitates this process using composition norms as formal representations of social norms. Conceptual graph theory is used to represent four categories of knowledge definitions: type definitions, state definitions, action norms and composition norms. It is shown how the composition norms guide the legitimate user-driven specification process by analysing a case on the development of an electronic law journal.     

A robust eigenspace method for obtaining feature values in high-speed massively parallel vision systems

Image-processing systems, each consisting of massively parallel photodetectors and digital processing elements on a monolithic circuit, are currently being developed by several researchers. Some earlyvision-like processing algorithms are installed in the vision systems. However, they are not sufficient for applications because their output is in the form of pattern information, so that, in order to respond to input, some feature values are required to be extracted from the pattern. In the present paper, we propose a robust method for extracting feature values associated with images in a massively parallel vision system.     

A design flow for supporting component-based software development in multiprocessor real-time systems

Component-based software development established as an effective technique to cope with the increasing complexity of modern computing systems. In the context of real-time systems, the M-BROE framework has been recently proposed to efficiently support component-based development of real-time applications on multiprocessor platforms in the presence of shared resources. The framework relies on a two-stage approach where software components are first partitioned upon a virtual multiprocessor platform and are later integrated upon the physical platform by means of component interfaces that abstract from the internal details of the applications. This work presents a complete design flow for the M-BROE framework. Starting from a model of software components, a first method is proposed to partition applications to virtual processors and perform a synthesis of multiple component interfaces. Then, a second method is proposed to support the integration of the components by allocating virtual processors to physical processors. Both methods take resource sharing into account. Experimental results are also presented to evaluate the proposed methodology.     

Building knowledge base management systems

Advanced applications in fields such as CAD, software engineering, real-time process control, corporate repositories and digital libraries require the construction, efficient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up, nor can they be built in terms of existing database technology, because such technology does not support the rich representational structure and inference mechanisms required for knowledge-based systems. This paper proposes a generic architecture for a knowledge base management system intended for such applications. The architecture assumes an object-oriented knowledge representation language with an assertional sublanguage used to express constraints and rules. It also provides for general-purpose deductive inference and special-purpose temporal reasoning. Results reported in the paper address several knowledge base management issues. For storage management, a new method is proposed for generating a logical schema for a given knowledge base. Query processing algorithms are offered for semantic and physical query optimization, along with an enhanced cost model for query cost estimation. On concurrency control, the paper describes a novel concurrency control policy which takes advantage of knowledge base structure and is shown to outperform two-phase locking for highly structured knowledge bases and update-intensive transactions. Finally, algorithms for compilation and efficient processing of constraints and rules during knowledge base operations are described. The paper describes original results, including novel data structures and algorithms, as well as preliminary performance evaluation data. Based on these results, we conclude that knowledge base management systems which can accommodate large knowledge bases are feasible. Edited by Gunter Schlageter and H.-J. Schek. Received May 19, 1994 / Revised May 26, 1995 / Accepted September 18, 1995     

A local method for contour matching and its parallel implementation

This paper presents a local approach for matching contour segments in an image sequence. This study has been primarily motivated by work concerned with the recovery of 3D structure using active vision. The method to recover the 3D structure of the scene requires to track in real-time contour segments in an image sequence. Here, we propose an original and robust approach that is ideally suited for this problem. It is also of more general interest and can be used in any context requiring matching of line boundaries over time. This method only involves local modeling and computation of moving edges dealing “virtually” with a contour segment primitive representation. Such an approach brings robustness to contour segmentation instability and to occlusion, and easiness for implementation. Parallelism has also been investigated using an SIMD-based real-time image-processing system. This method has been validated with experiments on several real-image sequences. Our results show quite satisfactory performance and the algorithm runs in a few milliseconds. Received: 11 December 1996 / Accepted: 8 August 1997     

Requirements Engineering, Soft Systems Methodology and Workforce Empowerment

The fidelity and practicality of using soft systems methodology (SSM) to empower the workforce such that its members can make a fuller contribution to the requirements engineering process is critically analysed. The detailed analysis is carried out by using a (critical) philosophical approach to develop an interpretation of (some key aspects of) requirements engineering practice in actual information systems development situations, utilising a number of practical requirements engineering studies. This analysis is built upon to explain the relationship between requirements engineering, SSM and workforce empowerment. It is concluded that, by maintaining critically focused attention on the economic context, it is theoretically possible to engineer requirements for information systems that would actually empower the workforce. However, the likelihood of using SSM successfully for this purpose is low, as the economic context in which requirements engineering takes place is largely ignored by the SSM advocates.     

User Interfaces for Applications on a Wrist Watch

Advances in technology have made it possible to package a reasonably powerful processor and memory subsystem coupled with an ultra high-resolution display and wireless communication into a wrist watch. This introduces a set of challenges in the nature of input devices, navigation, applications, and other areas. This paper describes a wearable computing platform in a wrist watch form-factor we have developed. We built two versions: one with a low resolution liquid crystal display; and another with a ultra high resolution organic light emitting diode display. In this paper we discuss the selection of the input devices and the design of applications and user interfaces for these two prototypes, and the compare the two versions.     

Towards a formalism to produce a programmer assistant CASE tool

A weak specification method important to the area of computer-aided software engineering (CASE) is introduced. The specification language introduced does not require the specification of control flow information. When given a specification consisting of a formula characterizing input constraints of a function and a formula characterizing output constraints, it is possible to synthesize program functions. The synthesis algorithm is guaranteed to find all functions which satisfy the specification. It is shown that when the algorithm is applied to the specifications, it is capable of producing all program structures, including sequences, selections, and iterations. Therefore, the methodology provides for a formal foundation upon which a CASE programmer assistant tool can be built