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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
Towards Adaptable and Adaptive Policy-Free Middleware
We believe that to fully support adaptive distributed applications,
middleware must itself be adaptable, adaptive and policy-free. In this paper we
present a new language-independent adaptable and adaptive policy framework
suitable for integration in a wide variety of middleware systems. This
framework facilitates the construction of adaptive distributed applications.
The framework addresses adaptability through its ability to represent a wide
range of specific middleware policies. Adaptiveness is supported by a rich
contextual model, through which an application programmer may control precisely
how policies should be selected for any particular interaction with the
middleware. A contextual pattern mechanism facilitates the succinct expression
of both coarse- and fine-grain policy contexts. Policies may be specified and
altered dynamically, and may themselves take account of dynamic conditions. The
framework contains no hard-wired policies; instead, all policies can be
configured.Comment: Submitted to Dependable and Adaptive Distributed Systems Track, ACM
SAC 200
Adaptive multiagent system for seismic emergency management
Presently, most multiagent frameworks are typically programmed in Java. Since the JADE platform has been recently ported to .NET, we used it to create an adaptive multiagent system where the knowledge base of the agents is managed using the CLIPS language, also called from .NET. The multiagent system is applied to create seismic risk scenarios, simulations of emergency situations, in which different parties, modeled as adaptive agents, interact and cooperate.adaptive systems, risk management, seisms.
Separating Agent-Functioning and Inter-Agent Coordination by Activated Modules: The DECOMAS Architecture
The embedding of self-organizing inter-agent processes in distributed
software applications enables the decentralized coordination system elements,
solely based on concerted, localized interactions. The separation and
encapsulation of the activities that are conceptually related to the
coordination, is a crucial concern for systematic development practices in
order to prepare the reuse and systematic integration of coordination processes
in software systems. Here, we discuss a programming model that is based on the
externalization of processes prescriptions and their embedding in Multi-Agent
Systems (MAS). One fundamental design concern for a corresponding execution
middleware is the minimal-invasive augmentation of the activities that affect
coordination. This design challenge is approached by the activation of agent
modules. Modules are converted to software elements that reason about and
modify their host agent. We discuss and formalize this extension within the
context of a generic coordination architecture and exemplify the proposed
programming model with the decentralized management of (web) service
infrastructures
A consistency framework for dynamic reconfiguration in AO-middleware architectures
Aspect-oriented (AO) middleware is a promising technology for the realisation of dynamic reconfiguration in distributed systems. Similar to other dynamic reconfiguration approaches, AO-middleware based reconfiguration requires that the consistency of the system is maintained across reconfigurations. AO middleware based reconfiguration is an ongoing research topic and several consistency approaches have been proposed. However, most of these approaches tend to be targeted at specific narrow contexts, whereas for heterogeneous distributed systems it is crucial to cover a wide range of operating conditions. In this paper we address this problem by exploring a flexible, framework-based consistency management approach that cover a wide range of operating conditions ensuring distributed dynamic reconfiguration in a consistent manner for AO-middleware architectures
RAFDA: A Policy-Aware Middleware Supporting the Flexible Separation of Application Logic from Distribution
Middleware technologies often limit the way in which object classes may be
used in distributed applications due to the fixed distribution policies that
they impose. These policies permeate applications developed using existing
middleware systems and force an unnatural encoding of application level
semantics. For example, the application programmer has no direct control over
inter-address-space parameter passing semantics. Semantics are fixed by the
distribution topology of the application, which is dictated early in the design
cycle. This creates applications that are brittle with respect to changes in
distribution. This paper explores technology that provides control over the
extent to which inter-address-space communication is exposed to programmers, in
order to aid the creation, maintenance and evolution of distributed
applications. The described system permits arbitrary objects in an application
to be dynamically exposed for remote access, allowing applications to be
written without concern for distribution. Programmers can conceal or expose the
distributed nature of applications as required, permitting object placement and
distribution boundaries to be decided late in the design cycle and even
dynamically. Inter-address-space parameter passing semantics may also be
decided independently of object implementation and at varying times in the
design cycle, again possibly as late as run-time. Furthermore, transmission
policy may be defined on a per-class, per-method or per-parameter basis,
maximizing plasticity. This flexibility is of utility in the development of new
distributed applications, and the creation of management and monitoring
infrastructures for existing applications.Comment: Submitted to EuroSys 200
Tiresias: Online Anomaly Detection for Hierarchical Operational Network Data
Operational network data, management data such as customer care call logs and
equipment system logs, is a very important source of information for network
operators to detect problems in their networks. Unfortunately, there is lack of
efficient tools to automatically track and detect anomalous events on
operational data, causing ISP operators to rely on manual inspection of this
data. While anomaly detection has been widely studied in the context of network
data, operational data presents several new challenges, including the
volatility and sparseness of data, and the need to perform fast detection
(complicating application of schemes that require offline processing or
large/stable data sets to converge).
To address these challenges, we propose Tiresias, an automated approach to
locating anomalous events on hierarchical operational data. Tiresias leverages
the hierarchical structure of operational data to identify high-impact
aggregates (e.g., locations in the network, failure modes) likely to be
associated with anomalous events. To accommodate different kinds of operational
network data, Tiresias consists of an online detection algorithm with low time
and space complexity, while preserving high detection accuracy. We present
results from two case studies using operational data collected at a large
commercial IP network operated by a Tier-1 ISP: customer care call logs and
set-top box crash logs. By comparing with a reference set verified by the ISP's
operational group, we validate that Tiresias can achieve >94% accuracy in
locating anomalies. Tiresias also discovered several previously unknown
anomalies in the ISP's customer care cases, demonstrating its effectiveness
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