In this paper, we present Reo, which forms a paradigm for composition of software components based on the notion of mobile channels. Reo is a channel-based exogenous coordination model in which complex coordinators, called connectors, are compositionally built out of simpler ones. The simplest connectors in Reo are a set of channels with well-defined behaviour supplied by users. Reo can be used as a language for coordination of concurrent processes, or as a ‘glue language’ for compositional construction of connectors that orchestrate component instances in a component-based system. The emphasis in Reo is just on connectors and their composition, and not on the entities that connect to, communicate and cooperate through these connectors. Each connector in Reo imposes a specific coordination pattern on the entities (for example, components) that perform I/O operations through that connector, without the knowledge of those entities. Channel composition in Reo is a very powerful mechanism for construction of connectors. We demonstrate the expressive power of connector composition in Reo through a number of examples. We show that exogenous coordination patterns that can be expressed as (meta-level) regular expressions over I/O operations can be composed in Reo out of a small set of only five primitive channel types.

This Special Issue of Mathematical Structures in Computer Science contains selected papers from ConCoord, the International Workshop on Concurrency and Coordination held in Lipari, Italy, on July 6–8, 2001 and associated to the 13th Lipari School for Computer Science Researchers on the Foundations of Wide Area Network Programming.

This paper describes the design and semantics of METAKLAIM, which is a higher order distributed process calculus equipped with staging mechanisms. METAKLAIM integrates METAML (an extension of SML for multi-stage programming) and KLAIM (a Kernel Language for Agents Interaction and Mobility), to permit interleaving of meta-programming activities (such as assembly and linking of code fragments), dynamic checking of security policies at administrative boundaries and ‘traditional’ computational activities on a wide area network (such as remote communication and code mobility). METAKLAIM exploits a powerful type system (including polymorphic types á la system F) to deal with highly parameterised mobile components and to enforce security policies dynamically: types are metadata that are extracted from code at run-time and are used to express trustiness guarantees. The dynamic type checking ensures that the trustiness guarantees of wide area network applications are maintained whenever computations interoperate with potentially untrusted components.

This paper presents the control system of a chess-playing robot developed by the Research Institute of Robots at the Shanghai Jiaotong University. Thanks to the Windows NT operation system and the RTX (Real-Time eXtension), the whole system can achieve good real-time performance. The control system, which is supported by a standard PC hardware platform and a modularized structure of system software, is open-ended and easily expansible.

This paper deseribes the control of multi-arm co-operating manipulator systems handling a common object. Inverse dynamics controllers with motive force compensation are developed for the co-operating fixed-base, free-floating, and free-flying space manipulator systems. Further, the relative performances of all the three configurations are compared on two tracking problems.

This paper deals with the design and development of a new perception system for controlling a set of ultrasonic transducers working at two different frequencies generated by a digital signal processor (DSP). Data gathering speed is increased by the simultaneous firing of sonars without crosstalk problems. The software and hardware implementation are presented as well as the results from the calibration process and the integration on board the mobile robot RAM-2. Finally, a demonstration of the use of the proposed equipment to wall-following via a fuzzy controller is described.

The choice of suitable high-level communication primitives for wide area network programming languages remains an open problem. This paper is driven by the practical consideration of providing an efficient and secure communication infrastructure for mobile agent systems. This has led us to formalise the Lime coordination middleware and propose a simplified model, which we call CoreLime, that addresses some of the main shortcomings of Lime while retaining its distinguishing feature, namely transient sharing of tuple spaces. We further discuss a prototype implementation along with security extensions. Our contribution is thus an exploration of the language design space rather than a theoretical investigation of properties of these models.

Vision-aided flexible link robot positoning using the Camera Space Manipulation (CSM) method is developed. The primary motivation for this work is to use an autonomous vision-aided robotic system to pick-up and accurately move a flexible object that it encounters. The work consists of analytical and experimental investigation of the performance of CSM for a kinematic model of the PUMA manipulator with a flexible structure at the wrist which accounts for the gravitation. Trade-offs between camera view parameters and axial deflection model parameters were investigated. View parameter reestimation and maneuvering resulted a very accurate placement of the end-effector at the target.

The benefits of using ontologies have been recognised in many areas such as knowledge and content management, electronic commerce and recently the emerging field of the Semantic Web. These new applications can be seen as a great success of research in ontologies. On the other hand, moving into real application comes with new challenges that need to be addressed on a principled level rather than for specific applications. This special issue will be devoted to less well-explored topics that have come into focus recently as a response to the new problems we face when trying to use ontologies in heterogeneous distributed environments. These environments include the use of ontologies in peer-to-peer and pervasive computing systems.