Refer Proceedings details

%T SpaceWire \- DS\-Links Reborn
%A Barry M. Cook, Paul Walker
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X DS\-links were created to provide a low\-latency, high
   performance data link between parallel processors. When the
   primary processor using them was withdrawn these links
   largely disappeared from view but were, in fact, still being
   used (albeit not for parallel computing) in the Space
   industry. The potential for these links, with their simple
   implementation, led to their adoption, in modified form, for
   a growing range of data communication applications. In 2003,
   the European Space Agency published a definition of
   DS\-links known as SpaceWire. We briefly describe the
   original DS\-links and detail how SpaceWire has kept or
   modified them to produce a now popular technology with a
   rapidly increasing number of implementations and wide
   take\-up.

%T An Introduction to CSP.NET
%A Alex Lehmberg, Martin N. Olsen
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X This paper reports on CSP.NET, developed over the last three
   months at the University of Copenhagen. CSP.NET is an object
   oriented CSP library designed to ease concurrent and
   distributed programming in Microsoft.NET 2.0. The library
   supports both shared memory multiprocessor systems and
   distributed\-memory multicomputers and aims towards making
   the architecture transparent to the programmer. CSP.NET
   exploits the power of .NET Remoting to provide the
   distributed capabilities and like JCSP, CSP.NET relies
   exclusively on operating system threads. A Name Server and a
   workerpool are included in the library, both implemented as
   Windows Services. This paper presents CSP.NET from a users
   perspective and provides a tutorial along with some
   implementation details and performance tests.

%T Performance Evaluation of JCSP Micro Edition: JCSPme
%A Kevin Chalmers, Jon Kerridge, Imed Romdhani
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Java has become a development platform that has migrated
   from its initial focus for small form devices, to large full
   scale desktop and server applications and finally back to
   the small in the form of Java enabled mobile phones. Here we
   discuss the necessary requirements to convert the existing
   JCSP framework so that it can be used in these resource
   constrained systems. We also provide some performance
   comparisons on various platforms to evaluate this
   implementation.

%T Ubiquitous Access to Site Specific Services by Mobile Devices: the Process View.
%A Jon Kerridge, Kevin Chalmers
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X The increasing availability of tri\-band mobile devices with
   mobile phone, wi\-fi and Bluetooth capability means that the
   opportunities for increased access by mobile devices to
   services provided within a smaller locality becomes
   feasible. This increase in availability might, however, be
   tempered by users switching off their devices as they are
   overloaded with a multitude of messages from a variety of
   sources. A wide range of opportunities can be realised if we
   can provide a managed environment in which people can access
   wireless services specific to a particular physical site or
   location in a ubiquitous manner, independent of the service,
   and they can also choose from which services they are
   willing to receive messages. These opportunities range from
   retail promotions as a person walks down the street, to
   shopper specific offers as people enter stores that utilise
   reward card systems, to information about bus arrivals at a
   bus stop, additional curatorial information within a museum
   and access to health records within a hospital environment.
   The CPA paradigm offers a real opportunity to provide such
   capability with mobile processes, rather than the current
   approach that, typically, gives users access to web pages.

%T CSP for .NET Based on JCSP
%A Kevin Chalmers, Sarah Clayton
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X We present a CSP framework developed for the .NET platform,
   building upon the ideas developed for the JCSP library.
   Discussing the development of the core functionality and
   then onto extra features in .NET that can be taken advantage
   of, we have created an initial platform that can provide
   simple development of CSP style process networks. However,
   we demonstrate that the Microsoft .NET implementation is
   more resource hungry for multi\-threaded applications than
   other approaches considered in this paper.

%T pony \- The occam\-pi Network Environment
%A Mario Schweigler, Adam T. Sampson
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Although concurrency is generally perceived to be a hard
   subject, it can in fact be very simple, provided that the
   underlying model is simple. The occam\-pi parallel
   processing language provides such a simple yet powerful
   concurrency model that is based on CSP and the pi\-calculus.
   This paper presents pony, the occam\-pi Network Environment.
   occam\-pi and pony provide a new, unified, concurrency model
   that bridges inter\- and intra\-processor concurrency. This
   enables the development of distributed applications in a
   transparent, dynamic and highly scalable way. The first part
   of this paper discusses the philosophy behind pony, explains
   how it is used, and gives a brief overview of its
   implementation. The second part evaluates pony\[rs]s
   performance by presenting a number of benchmarks.

%T A Study of Percolation Phenomena in Process Networks
%A Oliver Faust, Bernhard H.C. Sputh, Alastair R. Allen
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Percolation theory provides models for a wide variety of
   natural phenomena. One of these phenomena is the dielectric
   breakdown of composite materials. This paper describes how
   we implemented the percolation model for dielectric
   breakdown in a massively parallel processing environment. To
   achieve this we modified the breadth\-first search algorithm
   such that it works in probabilistic process networks. Formal
   methods were used to reason about this algorithm.
   Furthermore, this algorithm provides the basis for a JCSP
   implementation which models dielectric breakdowns in
   composite materials. The implementation model shows that it
   is possible to apply formal methods in probabilistic
   processing environments.

%T Portable CSP Based Design for Embedded Multi\-Core Systems
%A Bernhard H.C. Sputh, Oliver Faust, Alastair R. Allen
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Modern lifestyle depends on embedded systems. They are
   everywhere: sometimes they are hidden and at other times
   they are handled as a fashion accessory. In order to serve
   us better they have to do more and more tasks at the same
   time. This calls for sophisticated mechanisms to handle
   concurrency. In this paper we present CSP (Communicating
   Sequential Processes) as a method which helps to solve a
   number of problems of embedded concurrent systems. To be
   specific, we describe implementations of the commstime
   benchmark in multithreaded, multiprocessor and architecture
   fusion systems. An architecture fusion system combines
   machine and hardware\-logic architectures. Our results are
   twofold. First, architecture fusion systems outperform all
   the other systems we tested. Second, we implemented all the
   systems without a change in the design philosophy. The
   second point is the more important result, because it shows
   the power of CSP based design methods.

%T A JCSP.net Implementation of a Massively Multiplayer Online Game
%A Shyam Kumar, G. S. Stiles
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X We have developed a simple massively multiplayer online game
   system as a test bed for evaluating the usefulness and
   performance of JCSP.net. The system consists of a primary
   login server, secondary servers managing play on
   geographically distinct playing fields, and an arbitrary
   number of players. The basic structure of the game system is
   fairly simple, and has been verified to be free from
   deadlock and livelock using CSP and FDR. The JCSP.net
   implementation is straight\-forward and includes
   over\-writing buffers so that disconnected players will not
   block the servers and other players. Performance tests on
   local area networks under Windows demonstrate that five
   secondary servers easily support 1,000 machine\-generated
   players making moves every two to five seconds. The player
   move end\-to\-end time was about 65 milliseconds, which is
   considered fast enough to support fast\-action online games.
   Conversion from Windows to Linux required minimal effort;
   limited tests confirmed that versions using Linux alone, and
   Windows and Linux together, were also successful.

%T SystemCSP \- Visual Notation
%A Bojan Orlic, Jan F. Broenink
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X This paper introduces SystemCSP \- a design methodology
   based on a visual notation that can be mapped onto CSP
   expressions. SystemCSP is a graphical design specification
   language aimed to serve as a basis for the specification of
   formally verifiable component\-based designs of distributed
   real\-time systems. It aims to be a graphical formalism that
   covers various aspects needed for the design of distributed
   real\-time systems in single framework.

%T Interacting Components
%A Bojan Orlic, Jan F. Broenink
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X SystemCSP is a graphical modeling language based on both CSP
   and concepts of component\-based software development. The
   component framework of SystemCSP enables specification of
   both interaction scenarios and relative execution ordering
   among components. Specification and implementation of
   interaction among participating components is formalized via
   the notion of interaction contract. The used approach
   enables incremental design of execution diagrams by adding
   restrictions in different interaction diagrams throughout
   the process of system design. In this way all different
   diagrams are related into a single formally verifiable
   system. The concept of reusable formally verifiable
   interaction contracts is illustrated by designing set of
   design patterns for typical fault tolerance interaction
   scenarios.

%T TCP Input Threading in High Performance Distributed Systems
%A Hans Henrik Happe
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X TCP is the only widely supported protocol for reliable
   communication. Therefore, TCP is the obvious choice when
   developing distributed systems that need to work on a wide
   range of platforms. Also, for this to work a developer has
   to use the standard TCP interface provided by a given
   operating system. This work explores various ways to use
   TCP in high performance distributed systems. More precisely,
   different ways to use the standard Unix TCP API efficiently
   are explored, but the findings apply to other operating
   systems as well. The main focus is how various threading
   models affect TCP input in a process that has to handle both
   computation and I/O. The threading models have been
   evaluated in a cluster of Linux workstations and the results
   show that a model with one dedicated I/O thread generally is
   good. It is at most 10% slower than the best model in all
   tests, while the other models are between 30 to 194% slower
   in specific tests.

%T A Cell Transterpreter
%A Damian J. Dimmich, Christian L. Jacobsen, Matthew C. Jadud
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X The Cell Broadband Engine is a hybrid processor which
   consists of a PowerPC core and eight vector co\-processors
   on a single die. Its unique design poses a number of
   language design and implementation challenges. To begin
   exploring these challenges, we have ported the
   Transterpreter to the Cell Broadband Engine. The
   Transterpreter is a small, portable runtime for concurrent
   languages and can be used as a platform for experimenting
   with language concepts. This paper describes a preliminary
   attempt at porting the Transterpreter runtime to the Cell
   Broadband Engine and explores ways to program it using a
   concurrent language.

%T Mobile Robot Control: The Subsumption Architecture and occam\-pi
%A Jonathan Simpson, Christian L. Jacobsen, Matthew C. Jadud
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Brooks\[rs] subsumption architecture is a design paradigm
   for mobile robot control that emphasises re\-use of modules,
   decentralisation and concurrent, communicating processes.
   Through the use of occam\-pi the subsumption architecture
   can be put to use on general purpose modern robotics
   hardware, providing a clean and robust development approach
   for the creation of robot control systems.

%T Rain: A New Concurrent Process\-Oriented Programming Language
%A Neil C.C. Brown
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X This paper details the design of a new concurrent
   process\-oriented programming language, Rain. The language
   borrows heavily from occam\-p and C++ to create a new
   language based on process\-oriented programming, marrying
   channel\-based communication, a clear division between
   statement and expression, and elements of functional
   programming. An expressive yet simple type system, coupled
   with templates, underpins the language. Modern features such
   as Unicode support and 64\-bit integers are included from
   the outset, and new ideas involving permissions and coding
   standards are also proposed. The language targets a new
   virtual machine, which is detailed in a companion paper
   along with benchmarks of its performance.

%T Rain VM: Portable Concurrency through Managing Code
%A Neil C.C. Brown
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X A long\-running recent trend in computer programming is the
   growth in popularity of virtual machines. However, few have
   included good support for concurrency \- a natural mechanism
   in the Rain programming language. This paper details the
   design and implementation of a secure virtual machine with
   support for concurrency, which enables portability of
   concurrent programs. Possible implementation ideas of
   many\-to\-many threading models for the virtual machine
   kernel are discussed, and initial benchmarks are presented.
   The results show that while the virtual machine is slow for
   standard computation, it is much quicker at running
   communication\-heavy concurrent code \- within an order of
   magnitude of the same native code.

%T Native Code Generation using the Transterpreter.
%A Christian L. Jacobsen, Damian J. Dimmich, Matthew C. Jadud
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X We are interested in languages that provide powerful
   abstractions for concurrency and parallelism that execute
   everywhere, efficiently. Currently, the existing runtime
   environments for the occam\-pi programming language provide
   either one of these features (portability) or some semblance
   of the other (performance). We believe that both can be
   achieved through the careful generation of C from occam\-pi,
   and demonstrate that this is possible using the
   Transterpreter, a portable interpreter for occam\-pi, as our
   starting point.

%T Compositions of Concurrent Processes
%A Mark Burgin, Marc L. Smith
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X Using the extended model for view\-centric reasoning, EVCR,
   we focus on the many possibilities for concurrent processes
   to be composed. EVCR is an extension of VCR, both models of
   true concurrency; VCR is an extension of CSP, which is based
   on an interleaved semantics for modeling concurrency. VCR,
   like CSP, utilizes traces of instantaneous events, though
   VCR permits recording parallel events to preserve the
   perception of simultaneity by the observer(s). But observed
   simultaneity is a contentious issue, especially for events
   that are supposed to be instantaneous. EVCR addresses this
   issue in two ways. First, events are no longer
   instantaneous; they occur for some duration of time. Second,
   parallel events need not be an all\-or\-nothing proposition;
   it is possible for events to partially overlap in time.
   Thus, EVCR provides a more realistic and appropriate level
   of abstraction for reasoning about concurrent processes.
   With EVCR, we begin to move from observation to the
   specification of concurrency, and the compositions of
   concurrent processes. As one example of specification, we
   introduce a description of I/O\-PAR composition that leads
   to simplified reasoning about composite I/O\-PAR processes.

%T Software Specification Refinement and Verification Method with I\-Mathic Studio.
%A Gerald H. Hilderink
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X A software design usually manifests a composition of
   software specifications. It consists of hierarchies of black
   box and white box specifications which are subject to
   refinement verification. Refinement verification is a
   model\-checking process that proves the correctness of
   software specifications using formal methods. Although this
   is a powerful tool for developing reliable and robust
   software, the applied mathematics causes a serious gap
   between academics and software engineers. I\-Mathic
   comprehends a software specification refinement and
   verification method and a supporting toolset, which aims at
   eliminating the gap through hiding the applied mathematics
   by practical modelling concepts. The model\-checker FDR is
   used for refinement verification and detecting deadlocks and
   livelocks in software specifications. We have improved the
   method by incorporating CSP programming concepts into the
   specification language. These concepts make the method
   suitable for a broader class of safety\-critical concurrent
   systems. The improved I\-Mathic is illustrated in this
   paper.

%T Video Processing in occam\-pi
%A Carl G. Ritson, Adam T. Sampson, Frederick R. M. Barnes
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X The occam\-pi language provides many novel features for
   concurrent software development. This paper describes a
   video processing framework that explores the use of these
   features for multimedia applications. Processes are used to
   encapsulate operations on video and audio streams; mobile
   data types are used to transfer data between them
   efficiently, and mobile channels allow the process network
   to be dynamically reconfigured at runtime. We present
   demonstration applications including an interactive video
   player. Preliminary benchmarks show that the framework has
   comparable overhead to multimedia systems programmed using
   traditional methods.

%T No Blocking on Yesterday\[rs]s Embedded CSP Implementation (the Rubber Band of Getting it Right and Simple)
%A Øyvind Teig
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X This article is a follow\-up after the paper \[dq]From
   message queue to ready queue\[dq], presented at the ERCIM
   Workshop last year. A (mostly) synchronous layer had been
   implemented on top of an existing asynchronous run\-time
   system. After that workshop, we discovered that the initial
   implementation contained two errors: both concerning
   malignant process rescheduling associated with timers and
   \[rs]reuse\[rs] of the input side of a channel. Also, the
   set of process/dataflow patterns was not sufficient. To keep
   complexity low, we have made two new patterns to reflect
   better the semantic needs inherent in the application. Our
   assumption of correctness is also, this time, based both on
   heuristics and \[rs]white\-board reasoning\[rs]. However,
   both the previous and this paper have been produced before
   any first shipment of the product, and well within
   full\-scale testing. Our solutions and way of attacking the
   problems have been in an industrial tradition.

%T A Circus Development and Verification of an Internet Packet Filter.
%A Alistair A. McEwan
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X In this paper, we present the results of a significant and
   large case study in Circus. Development is top\-down \- from
   a sequential abstract specification about which safety
   properties can be verified, to a highly concurrent
   implementation on a Field Programmable Gate Array.
   Development steps involve applying laws of Circus allowing
   for the refinement of specifications; confidence in the
   correctness of the development is achieved through the
   applicability of the laws applied; proof obligations are
   discharged using the model\-checker for CSP, FDR, and the
   theorem prover for Z, Z/Eves. An interesting feature of this
   case study is that the design of the implementation is
   guided by domain knowledge of the application \- the
   application of this domain knowledge is supported by, rather
   than constrained by the calculus. The design is not what
   would have been expected had the calculus been applied
   without this domain knowledge. Verification highlights a
   curious error made in early versions of the implementation
   that were not detected by testing.

%T Classification of Programming Errors in Parallel Message Passing Systems
%A Jan Bækgaard Pedersen
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X In this paper we investigate two major topics; firstly,
   through a survey given to graduate students in a parallel
   message passing programming class, we categorize the errors
   they made (and the ways they fixed the bugs) into a number
   of categories. Secondly, we analyze these answers and
   provide some insight into how software could be built to aid
   the development, deployment, and debugging of parallel
   message passing systems. We draw parallels to similar
   studies done for sequential programming, and finally show
   how the idea of multilevel debugging relates to the results
   from the survey.

%T Compiling CSP
%A Frederick R. M. Barnes
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006
%X CSP, Hoare\[rs]s Communicating Sequential Processes, is a
   formal language for specifying, implementing and reasoning
   about concurrent processes and their interactions. Existing
   software tools that deal with CSP directly are largely
   concerned with assisting formal proofs. This paper presents
   an alternative use for CSP, namely the compilation of CSP
   systems to executable code. Themain motivation for this work
   is in providing a means to experimentwith relatively large
   CSP systems, possibly consisting millions of concurrent
   processes \- something that is hard to achieve with the
   tools currently available.

%T A Fast Resolution of Choice between Multiway Synchronisations
%A Peter H. Welch
%E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes
%B Communicating Process Architectures 2006

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