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We present fpga-ToPSS (Toronto Publish/ Subscribe System), an efficient FPGA-based middleware platform geared towards high-frequency and low-latency event processing. fpga-ToPSS is built over reconfigurable hardware---FPGAs---to achieve line-rate processing by exploiting unprecedented degrees of parallelism and potential for pipelining,only available through custom-built, application-specific and low-level logic design. Furthermore, our middleware solution hosts an event processing engine that is built on a hardware-based packet processor and Boolean expression matcher. Our middleware vision extends to a wide range of applications including real-time data analytics, intrusion detection, algorithmic trading, targeted advertisement, and (complex) event processing.

The proliferation of small devices and the advancements in various technologies have introduced the concept of pervasive environments. In these environments, user tasks can be executed by using the deployed components provided by devices with different capabilities. One appropriate paradigm for building user tasks for pervasive environments is Service-Oriented Architecture (SOA). Using SOA, user tasks are represented as an assembly of abstract components (i.e., services) without specifying their implementations, thus they should be resolved into concrete components. The task resolution involves automatic matching and selection of components across various devices. For this purpose, we present an approach that allows for each service of a user task, the selection of the best device and component by considering the user preferences, devices capabilities, services requirements and components preferences. Due to the dynamicity of pervasive environments, we are interested in the continuity of execution of user tasks. Therefore, we present an approach that allows components to monitor locally or remotely the changes of properties, which depend on. We also considered the adaptation of user tasks to cope with the dynamicity of pervasive environments. To overcome captured failures, the adaptation is carried out by a partial reselection of devices and components. However, in case of mismatching between an abstract user task and a concrete level, we propose a structural adaptation approach by injecting some defined adaptation patterns, which exhibit an extra-functional behavior. We also propose an architectural design of a middleware allowing the task's resolution, monitoring of the environment and the task adaptation. We provide implementation details of the middleware's components along with evaluation results

We present fpga-ToPSS (Toronto Publish/ Subscribe System), an efficient FPGA-based middleware platform geared towards high-frequency and low-latency event processing. fpga-ToPSS is built over reconfigurable hardware---FPGAs---to achieve line-rate processing by exploiting unprecedented degrees of parallelism and potential for pipelining,only available through custom-built, application-specific and low-level logic design. Furthermore, our middleware solution hosts an event processing engine that is built on a hardware-based packet processor and Boolean expression matcher. Our middleware vision extends to a wide range of applications including real-time data analytics, intrusion detection, algorithmic trading, targeted advertisement, and (complex) event processing.

The explosion in processing power of embedded systems has enabled distributed embedded networks to perform more complicated tasks. Middleware are sets of encapsulations of common and network/operating system-specific functionality into generic, reusable frameworks to manage such distributed networks. This thesis will survey and categorize popular middleware implementations into three adapted layers: host-infrastructure, distribution, and common services. This thesis will then apply a quantitative approach to grading and proposing a single middleware solution from all layers for two target platforms: CubeSats and autonomous unmanned aerial vehicles (UAVs). CubeSats are 10x10x10cm nanosatellites that are popular university-level space missions, and impose power and volume constraints. Autonomous UAVs are similarly-popular hobbyist-level vehicles that exhibit similar power and volume constraints. The MAVLink middleware from the host-infrastructure layer is proposed as the middleware to manage the distributed embedded networks powering these platforms in future projects. Finally, this thesis presents a performance analysis on MAVLink managing the ARM Cortex-M 32-bit processors that power the target platforms.

In the context of a society were the Web is present in many aspects, there is asignificant amount of visually impaired users whose experience is far from beingsatisfactory. There are technologies aiming this problem but still with no full suc-cess. The problem addressed in this project is the existing gap between the visuallyimpaired users and the solutions being offered to them. As a solution to this problem,a middleware prototype is developed. It acts as a web application so the user doesnot need to install anything. The middleware also offers different adaptations to theuser such as amplifying lens, text narrator, and others. The solution was tested byvisually impaired users and it received an overall positive result. Some features likethe amplifying lens received a good value and some of them need further improve-ment.

A flexible, scalable, and asynchronous middleware abstract is needed for business process management, which involves thousands of tasks and a large number of running instances of large business processes. The content-based publish/subscribe system is an ideal candidate to serve as enterprise service bus for these applications. In the publish/subscribe paradigm, information providers called publishers disseminate publications to all subscribers who have expressed interests by registering subscriptions through a loosely coupled interface. However, the traditional publish/subscribe paradigm only supports stateless subscriptions, that is, event correlation is ignored. Moreover, subscribers can only receive publications issued after their subscriptions. There are many application contexts, however, where access to publications from the past is necessary,such as for replaying a business process execution to debug it. Even more interesting uses arise when data from the past can be correlated with those in the future. Therefore, new languages and new functionalities are needed in the standard publish/subscribe model in order to support business process management. A new subscription language PADRES SQL(PSQL) which can express event patterns and unify both historic and future views for subscribers. PADRES allows a subscriber to access data published both in the past and in the future. Furthermore, complex event detection happens in the broker network. The main difficulties of distributed event detection are routing a composite subscription, including where and how to decompose the composite subscription, and routing the individual parts of the subscription. Our composite subscription routing decisions are based on a cost model which minimizes the routing and detection delay. An adaptive subscription routing protocol is proposed to determine efficient location with dynamic changing workloads. PADRES also provides robust message delivery by exploring alternative paths in a cyclic overlay. Routing optimizations and efficient matching algorithms are studied to improve the performance of the extended publish/subscribe model. With the above features, we propose the Ninos system, the distributed business process execution architecture as a case study,which uses light-weight activity agents to carry out business process execution in a distributed environment. Ninos proves that decentralized business process execution is the trend for next generation products, and the publish/subscribe model is ideal to serve as an enterpriser service bus (ESB) for distributed applications.

The Publish/Subscribe (pub/sub) model has been widely applied in a variety of application scenarios which demand loose-coupling and asynchronous communication between a large number of information sources and sinks. In this model, clients are granted the flexibility to specify their interests at a high level and rely on the pub/sub middleware for delivery of their publications of interest. This increased flexibility and ease of use on the client side results in substantial complexity on part of the pub/sub middleware implementation. Furthermore, for several reasons including improved scalability, availability and avoiding a single point of failure, the pub/sub middleware is commonly composed of a set of collaborating message routers, a.k.a. brokers. The distributed nature of this design further introduces new challenges in ensuring end-to-end reliability as well as efficiency of operation. These challenges are largely unique to the pub/sub model and hence absent in both point-to-point or multicast protocols. This thesis develops solutions that ensure the dependable operation of the pub/sub system by exploiting the notion of overlay neighborhoods in a formal manner. More specifically, brokers maintain information about their neighbors within a configurable distance in the pub/sub overlay and exploit this knowledge to construct alternative forwarding paths or make smart forwarding decisions that improves efficiency, bandwidth utilization and delivery delay, all at the same time. Furthermore, in the face of failures overlay neighborhoods enable fast reconstruction of forwarding paths in the system without compromising its reliability and availability. Finally, as an added benefit of overlay neighborhoods, this thesis develops large-scale algorithms that bring the advantages of the pub/sub model to the domain of file sharing and bulk content dissemination applications. Experimental evaluation results with deployments as large as 1000 nodes illustrate that the pub/sub system scales well and outperforms the traditional BitTorrent protocol in terms of content dissemination delay.

Dynamic selection and composition of autonomous and loosely-coupled Web services is increasingly used to automate business processes. The typical long-running characteristic of business processes imposes new management challenges such as dynamic adaptation of running process instances. However, current process orchestration engines provide limited flexibility to dynamically adapt to changing runtime conditions (e.g., presence of faults). Additionally, current process specification languages exhibit some limitations regarding modularity of crosscutting management concerns. In particular, monitoring and adaptation logic is often scattered across several process definitions and intertwined with the business logic. This leads to monolithic and complex processes that are hard to understand, reuse, maintain, and evolve. To address these limitations, we developed a policy-based change management framework, named Manageable and Adaptable Service Compositions (MASC), to declaratively express crosscutting monitoring and process adaptation concerns in a separate and modular way. MASC policies use a set of simple, but flexible and relatively powerful, constructs to declaratively specify policies that govern: (1) discovery and selection of services to be used, (2) monitoring to detect the need for adaptation, (3) reconfiguration and adaptation of the process to handle special cases (e.g., context-dependant behaviour) and recover from typical faults in service-based processes. The identified constructs are executed by a lightweight service-oriented management middleware named MASC middleware. The adaptation is transparent because it preserves the original functional behaviour of the business process and does not tangle the adaptation logic with that of the business process. Additionally, policies do not have to be necessarily defined when designing the process; they can also be introduced later during deployment or at runtime. We implemented a MASC proof-of-concept prototype and evaluated it on Stock Trading case study scenarios. We conducted extensive studies to demonstrate the feasibility of the proposed techniques and illustrate the benefits of our approach in providing adaptive composite services using the policy-based approach. Our performance and scalability studies indicate that MASC middleware is scalable and the introduced overhead are acceptable.

Zugl.: Dresden, Techn. Universiẗat, Diss., 2008.