Towards an aspect weaving BPEL engine

This position paper proposes the use of dynamic aspects and the visitor design pattern to obtain a highly configurable and extensible BPEL engine. Using these two techniques, the core of this infrastructural software can be customised to meet new requirements and add features such as debugging, execution monitoring, or changing to another Web Service selection policy. Additionally, it can easily be extended to cope with customer-specific BPEL extensions. We propose the use of dynamic aspects not only on the engine itself but also on the workflow in order to tackle the problems of Web Service hot deployment and hot fixes to long running processes. In this way, composing aWeb Service "on-the-fly" means weaving its choreography interface into the workflow

Efficient Aggregated Deliveries with Strong Guarantees in an Event-based Distributed System

A popular approach to designing large scale distributed systems is to follow an event-based approach. In an event-based approach, a set of software components interact by producing and consuming events. The event-based model allows for the decoupling of software components, allowing distributed systems to scale to a large number of components. Event correlation allows for higher order reasoning of events by constructing complex events from single, consumable events. In many cases, event correlation applications rely on centralized setups or broker overlay networks. In the case of centralized setups, the guarantees for complex event delivery are stronger, however, centralized setups create performance bottlenecks and single points of failure. With broker overlays, the performance and fault tolerance are improved but at the cost of weaker guarantees

The design and implementation of a P2P-based composite event notification system

The development of large, open, and heterogeneous distributed systems is becoming increasingly dependent on event services to bind together the components of an application in such a way that they are able to react to changes in other components. One way to distribute event notifications around a distributed environment is to use content-based publish/ subscribe communication. Such a system mediates between publishers of information and subscribers who sign up to receive information by routing messages across the network from their source to the point of subscription using the message content and the client subscriptions. Although content-based publish/subscribe has been used successfully to develop simple event notification systems, in which events are routed through from external publisher to external client, more complex systems are possible that create new events, known as composites, based on the detection of patterns of events. Composite event notification, however, poses a number of challenges, including network management and network routing. In this paper, we discuss the design and implementation of a composite event notification system over a Chord-based peer-to-peer network using JXTA, and how we have addressed these challenges

Mobile Service Clouds: A self-managing infrastructure for autonomic mobile computing services

Abstract. We recently introduced Service Clouds, a distributed infrastructure designed to facilitate rapid prototyping and deployment of autonomic communication services. In this paper, we propose a model that extends Service Clouds to the wireless edge of the Internet. This model, called Mobile Service Clouds, enables dynamic instantiation, composition, configuration, and reconfiguration of services on an overlay network to support mobile computing. We have implemented a prototype of this model and applied it to the problem of dynamically instantiating and migrating proxy services for mobile hosts. We conducted a case study involving data streaming across a combination of PlanetLab nodes, local proxies, and wireless hosts. Results are presented demonstrating the effectiveness of the prototype in establishing new proxies and migrating their functionality in response to node failures.