The combination of improved battery technology and more power-efficient computing hardware has led to the proliferation of heterogeneous distributed systems. This internet of things consists of embedded, wearable, hobbyist, parallel, and commodity devices. Given the different resource and power constraints of such systems, applications must be able to reconfigure or adapt their runtime execution environment in order to make best use of the resources available. In order for the underlying operating system/runtime to support runtime adaptation, an application must be suitably designed. The actor model of computation presents a natural fit for programming such adaptive systems with shared-nothing semantics and use of message passing. This paper addresses the limitations of current actor approaches and argues that an actor is the appropriate unit of adaptation. This is justified through experimentation across heterogeneous platforms.

GPU and multicore hardware architectures are commonly used in many different application areas to accelerate problem solutions relative to single CPU architectures. The typical approach to accessing these hardware architectures requires embedding logic into the programming language used to construct the application; the two primary forms of embedding are: calls to API routines to access the concurrent functionality, or pragmas providing concurrency hints to a language compiler such that particular blocks of code are targeted to the concurrent functionality. The former approach is verbose and semantically bankrupt, while the success of the latter approach is restricted to simple, static uses of the functionality.

Home wireless networks are difficult to manage and comprehend because of evolving locality, co-locality, connectivity and interaction. We define formal models of home wireless network infrastructure and policies and investigate how they can be used in a network management system designed to provide user-oriented support. We model spatial and temporal behaviour of network interactions and user-initiated network policies and define an online framework for generation of models from network and user-initiated events. The models are expressed in an extension to Milnerʼs bigraphical reactive systems. Analysis of the models is carried out in real-time by a bespoke bigraph reasoning system based on checking predicates, which is encoded as bigraph matching. Real-time model generation and analysis is implemented on the experimental Homework system router and trialled with synthetic and actual network data.

This paper presents a user driven redesign of the domestic network infrastructure that draws upon a series of ethnographic studies of home networks. We present an infrastructure based around a purpose built access point that has modified the handling of protocols and services to reflect the interactive needs of the home. The developed infrastructure offers a novel measurement framework that allows a broad range of infrastructure information to be easily captured and made available to interactive applications. This is complemented by a diverse set of novel interactive control mechanisms and interfaces for the underlying infrastructure. We also briefly reflect on the technical and user issues arising from deployments.

Home networks have evolved to become small-scale versions of enterprise networks. The tools for visualizing and managing such networks are primitive and continue to require networked systems expertise on the part of the home user. As a result, non-expert home users must manually manage non-obvious aspects of the network - e.g., MAC address filtering, network masks, and firewall rules, using these primitive tools. The Homework information plane architecture uses stream database concepts to generate derived events from streams of raw events. This supports a variety of visualization and monitoring techniques, and also enables construction of a closed-loop, policy-based management system. This paper describes the information plane architecture and its associated policy-based management infrastructure. Exemplar visualization and closed-loop management applications enabled by the resulting system (tuned to the skills of non-expert home users) are discussed.

The Homework project has examined redesign of existing home network infrastructures to better support the needs and requirements of actual home users. Integrating results from several ethnographic studies, we have designed and built a home networking platform providing detailed per-flow measurement and management capabilities supporting several novel management interfaces. This demo specifically shows these new visualization and control interfaces (1), and describes the broader benefits of taking an integrated view of the networking infrastructure, realised through our router's augmented measurement and control APIs (2).

Heterogeneous multi-core processors, such as the IBM Cell processor, can deliver high performance. However, these processors are notoriously difficult to program: different cores support different instruction set architectures, and the processor as a whole does not provide coherence between the different cores’ local memories. We present Hera-JVM, an implementation of the Java Virtual Machine which operates over the Cell processor, thereby making this platforms more readily accessible to mainstream developers. Hera-JVM supports the full Java language; threads from an unmodified Java application can be simultaneously executed on both the main PowerPC-based core and on the additional SPE accelerator cores. Migration of threads between these cores is transparent from the point of view of the application, requiring no modification to Java source code or bytecode. Hera-JVM supports the existing Java Memory Model, even though the underlying hardware does not provide cache coherence between the different core types. We examine Hera-JVM’s performance under a series of real-world Java benchmarks from the SpecJVM, Java Grande and Dacapo benchmark suites. These benchmarks show a wide variation in relative performance on the different core types of the Cell processor, depending upon the nature of their workload. Execution of these benchmarks on Hera-JVM can achieve speedups of up to 2.25x by using one of the Cell processor’s SPE accelerator cores, compared to execution on the main PowerPC-based core. When all six SPE cores are exploited, parallel workloads can achieve speedups of up to 13x compared to execution on the single PowerPC core.

GMPLS is viewed as an attractive intelligent control plane for different network technologies and graceful restart is a key technique in ensuring this control plane is resilient and able to recover adequately from faults. This paper studies the graceful restart mechanism recently proposed for a key GMPLS protocol, RSVP-TE. The performance of RSVP-TE graceful restart is evaluated in a variety of scenarios, with the impact of factors such as the number of data plane connections, the degree of the restarting node and the manner in which recovery messages are sent explored. The results obtained give significant insight into the behaviour and performance of RSVP-TE graceful restart and the findings are leveraged to propose techniques and guidelines to improve the performance of RSVP-TE graceful restart.

An increasing number of processor architectures support scratch-pad memory - software managed on-chip memory. Scratch-pad memory provides low latency data storage, like on-chip caches, but under explicit software control. The simple design and predictable nature of scratchpad memories has seen them incorporated into a number of embedded and real-time system processors. They are also employed by multi-core architectures to isolate processor core local data and act as low latency inter-core shared memory.

Abstract Future e‐Health systems will consist of low‐power on‐body wireless sensors attached to mobile users that interact with an ubiquitous computing environment to monitor the health and well being of patients in hospitals or at home. Patients or health practitioners have very little technical computing expertise so these systems need to be self‐configuring and self‐managing with little or no user input. More importantly, they should adapt autonomously to changes resulting from user activity, device failure, and the addition or loss of services. We propose the Self‐Managed Cell (SMC) as an architectural pattern for all such types of ubiquitous computing applications and use an e‐Health application in which on‐body sensors are used to monitor a patient living in their home as an exemplar. We describe the services comprising the SMC and discuss cross‐SMC interactions as well as the composition of SMCs into larger structures. Copyright © 2007 John Wiley & Sons, Ltd.

Network intrusion detection systems typically detect worms by examining packet or flow logs for known signatures. Not only does this approach mean worms cannot be detected until the signatures are created, but that variants of known worms will remain undetected since they will have different signatures. The intuitive solution is to write more generic signatures. This solution, however, would increase the false alarm rate and is therefore practically not feasible. This paper reports on the feasibility of using a machine learning technique to detect variants of known worms in real-time.

GMPLS is viewed as an attractive intelligent control plane for different network technologies and graceful restart is a key technique to ensure this control plane is resilient and able to recover adequately from faults. This paper analyses the graceful restart mechanism proposed for a key GMPLS protocol, RSVP-TE. A novel analytical model, which may be readily adapted to study other protocols, is developed. This model allows the efficacy of graceful restart to be evaluated in a number of scenarios. It is found that, unsurprisingly, increasing control message loss and increasing the number of data plane connections both increased the time to complete recovery. It was also discovered that a threshold exists beyond which a relatively small change in the control message loss probability causes a disproportionately large increase in the time to complete recovery. The interesting findings in this work suggest that the performance of graceful restart is worthy of further investigation, with emphasis being placed on exploring procedures to optimise the performance of graceful restart.

Despite several advantages inherent in mobile-agent- based approaches to network management as compared to traditional SNMP-based approaches, industry is reluctant to adopt the mobile agent paradigm as a replacement for the existing manager-agent model; the management community requires an evolutionary, rather than a revolutionary, use of mobile agents. Furthermore, security for distributed management is a major concern; agent-based management systems inherit the security risks of mobile agents. We have developed a Java-based mobile agent infrastructure for network management that enables the safe integration of mobile agents with the SNMP protocol. The security of the system has been evaluated under agent to agent-platform and agent to agent attacks and has proved trustworthy in the performance of network management tasks.

Body sensor networks consisting of low-power on- body wireless sensors attached to mobile users will be used in the future to monitor the health and well being of patients in hospitals or at home. Such systems need to adapt autonomously to changes in context, user activity, device failure, and the availability or loss of services. To this end, we propose a policy- based architecture that uses the concept of a Self-Managed Cell (SMC) to integrate services, managed resources and a policy interpreter by means of an event bus. Policies permit the declarative specification of adaptation strategy for self- configuration and self-management. We present the design and implementation of the SMC and describe its potential use in a scenario for management of heart monitoring. Preliminary performance measurements are also presented and discussed.

The middleware market represents a sizable segment of the overall Information and Communication Technology market. In 2005, the annual middleware license revenue was reported by Gartner to be in the region of $8.5 billion. In this article we address the question whether research had any involvement in the creation of the technology that is being sold in this market? We attempt a scholarly discourse. We present the research method that we have applied to answer this question. We then present a brief introduction into the key middleware concepts that provide the foundation for this market. It would not be feasible to investigate any possible impact that research might have had. Instead we select a few very successful technologies that are representative for the middleware market as a whole and show the existence of impact of research results in the creation of these technologies. We investigate the origins of Web services middleware, distributed transaction processing middleware, message-oriented middleware, distributed object middleware and remote procedure call systems. For each of these technologies we are able to show ample influence of research and conclude that without the research conducted by PhD students and researchers in university computer science labs at Brown, CMU, Cambridge, Newcastle, MIT, Vrije, and University of Washington as well as research in industrial labs at APM, AT&T Bell Labs, DEC Systems Research, HP Labs, IBM Research, and Xerox PARC we would not have middleware technology in its current form. We summarise the article by distilling lessons that can be learnt from this evidenced impact for future technology transfer undertakings.

The current practice of physical science research has yielded a continuously growing demand for interconnection network bandwidth to support the sharing of large datasets. Academic research networks and internet service providers have provisioned their networks to handle this type of load, which generates prolonged, high-volume traffic between nodes on the network. Maintenance of QoS for all network users demands that the onset of these (Grid bulk) transfers be detected to enable them to be reengineered through resources specifically provisioned to handle this type of traffic. This paper describes a real-time detector that operates at full-line-rate on Gb/s links, operates at high connection rates, and can track the use of ephemeral or non-standard ports.

The proposed uses of the resource reservation protocol (RSVP) now extend beyond reserving resources in Internet protocol (IP) networks to being a generic signaling protocol for generalised multi-protocol label switching (GMPLS). In any implementation of RSVP, there are a number of discretionary timing parameters, the values of which affect the efficacy of RSVP in establishing and maintaining reservations/connections. This work frames the interactions between key RSVP timing parameters and performance metrics as a multi-objective optimisation problem which, due to its intractable nature, is tackled using a reputable multi-objective evolutionary algorithm. It is shown that this approach is a feasible means of exploring many of the innate tradeoffs in soft-state protocols such as RSVP. This approach facilitates an extensive comparison of a number of variants of RSVP: standard RSVP, RSVP featuring the recently standardised retransmission algorithm and two subsequent variants of this algorithm, supporting the asymmetric delivery of RSVP control messages. These RSVP variants are compared in terms of multiple performance metrics under a number of different exemplar network conditions, giving insight into their relative merits. Furthermore, the relative significance of the different timing parameters is investigated and their most expedient values determined.

Measurement-based performance evaluation of network traffic is becoming very important, especially for networks trying to provide differentiated levels of service quality to the different application flows. The nonidentical response of flows to the different types of network-imposed performance degradation raises the need for ubiquitous measurement mechanisms, able to measure numerous performance properties, and being equally applicable to different applications and transports. This paper presents a new measurement mechanism, facilitated by the steady introduction of IPv6 in network nodes and hosts, which exploits native features of the protocol to provide support for performance measurements at the network (IP) layer. IPv6 Extension Headers have been used to carry the triggers involving the measurement activity and the measurement data in-line with the payload data itself, providing a high level of probability that the behaviour of the real user traffic flows is observed. End-to-end one-way delay, jitter, loss, and throughput have been measured for applications operating on top of both reliable and unreliable transports, over different-capacity IPv6 network configurations. We conclude that this technique could form the basis for future Internet measurements that can be dynamically deployed where and when required in a multiservice IP environment.

The ability to measure, monitor and control the service quality experienced by network traffic is becoming increasingly important as multiple traffic types are aggregated onto IP networks. Assessing the real-time performance of the application flows is an essential requirement for network operations and service management, as well as for identifying how the different traffic types and transports interact and behave, when they are carried over the end-to-end Internet infrastructure. This paper introduces a novel measurement technique for assessing the performance of IPv6 network flows. By exploiting IPv6 extension headers, measurement triggers and the instantaneous measurement indications are carried in the same packets as the payload data itself. providing a high level of probability that the behaviour of the real user traffic flows is being observed. The measurement mechanism is applied at the network layer and provides for a generic technique able to measure any type of traffic without depending on particular transports or on specific measurement architectures. A prototype implementation of this technique is also described and evaluated by measuring performance properties of application flows over different-capacity IPv6 environments. End-to-end delay and jitter of video streams have been measured, as well as the goodput for services operating on top of reliable transport. This measurement technique can be the basis for low-overhead, scalable, transparent and reliable measurement of individual and aggregate network flows, and can be dynamically deployed where and when required in a multi-service IP environment.

Abstract Many distributed applications have a strong requirement for efficient dissemination of large amounts of information to widely spread consumers in large networks. These include applications in e‐commerce and telecommunication. Publish/subscribe is considered one of the most important interaction styles with which to model communication on a large scale. Producers publish information on a topic and consumers subscribe to the topics they wish to be informed of. The decoupling of producers and consumers in time, space, and flow makes the publish/subscribe paradigm very attractive for large scale distribution, especially in environments like the Internet. This paper describes the architecture and implementation of DACE (Distributed Asynchronous Computing Environment), a framework for publish/subscribe communication based on an object‐oriented programming abstraction in the form of Distributed Asynchronous Collection (DAC). DACs capture the variants of publish/subscribe, without blurring their respective advantages. The architecture we present is tolerant of network partitions and crash failures. The underlying model is based on the notion of Topic Membership: a weak membership for the parties involved in a topic. We present how Topic Membership enables the realization of a robust and efficient reliable multicast on a large scale. The protocol ensures that, inside a topic, even a subscriber who is temporarily partitioned away eventually receives a published message. Copyright © 2001 John Wiley & Sons, Ltd.

We describe a lightweight application sharing infrastructure that enables collaborative design using graphics intensive applications over low bandwidth networks. The basis of the technology employs an event driven-mechanism to share a reduced event set among multiple copies of an application executing on different workstations. This technology is referred as RES-AP (Reduced Event Set Application Sharing). RES-AP allows geographically-dispersed engineers to work together on large complex problems with fast responses. This capability is achieved without modification to the applications or to the window system software.