195,799 research outputs found
Applying tropos to socio-technical system design and runtime configuration
Recent trends in Software Engineering have introduced the importance of reconsidering the traditional idea of software design as a socio-tecnical problem, where human agents are integral part of the system along with hardware and software components. Design and runtime support for Socio-Technical Systems (STSs) requires appropriate modeling techniques and
non-traditional infrastructures. Agent-oriented software methodologies are natural solutions to the development of STSs, both humans and technical components are conceptualized and analyzed as part of the same system. In this paper, we illustrate a number of Tropos features that we believe fundamental to support the development and runtime reconfiguration of STSs.
Particularly, we focus on two critical design issues: risk analysis and location variability. We show how they are integrated and used into a planning-based approach to support the designer in evaluating and choosing the best design alternative. Finally, we present a generic framework to develop self-reconfigurable STSs
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Education as a Complex System: Conceptual and Methodological Implications
Education is a complex system, which has conceptual and methodological implications for education research and policy. In this article, an overview is first provided of the Complex Systems Conceptual Framework for Learning (CSCFL), which consists of a set of conceptual perspectives that are generally shared by educational complex systems, organized into two focus areas: collective behaviors of a system, and behaviors of individual agents in a system. Complexity and research methodologies for education are then considered, and it is observed that commonly used quantitative and qualitative techniques are generally appropriate for studying linear dynamics of educational systems. However, it is proposed that computational modeling approaches, being extensively used for studying nonlinear characteristics of complex systems in other fields, can provide a methodological complement to quantitative and qualitative education research approaches. Two research case studies of this approach are discussed. We conclude with a consideration of how viewing education as a complex system using complex systems’ conceptual and methodological tools can help advance education research and also inform policy
Securing open multi-agent systems governed by electronic institutions
One way to build large-scale autonomous systems is to develop an open multi-agent system
using peer-to-peer architectures in which agents are not pre-engineered to work together and in
which agents themselves determine the social norms that govern collective behaviour. The social
norms and the agent interaction models can be described by Electronic Institutions such as those
expressed in the Lightweight Coordination Calculus (LCC), a compact executable specification
language based on logic programming and pi-calculus. Open multi-agent systems have
experienced growing popularity in the multi-agent community and are expected to have many
applications in the near future as large scale distributed systems become more widespread, e.g.
in emergency response, electronic commerce and cloud computing. A major practical limitation
to such systems is security, because the very openness of such systems opens the doors to
adversaries for exploit existing vulnerabilities.
This thesis addresses the security of open multi-agent systems governed by electronic
institutions. First, the main forms of attack on open multi-agent systems are introduced and
classified in the proposed attack taxonomy. Then, various security techniques from the literature
are surveyed and analysed. These techniques are categorised as either prevention or detection
approaches. Appropriate countermeasures to each class of attack are also suggested.
A fundamental limitation of conventional security mechanisms (e.g. access control and
encryption) is the inability to prevent information from being propagated. Focusing on
information leakage in choreography systems using LCC, we then suggest two frameworks to
detect insecure information flows: conceptual modeling of interaction models and language-based
information flow analysis. A novel security-typed LCC language is proposed to address
the latter approach.
Both static (design-time) and dynamic (run-time) security type checking are employed to
guarantee no information leakage can occur in annotated LCC interaction models. The proposed
security type system is then formally evaluated by proving its properties. A limitation of both
conceptual modeling and language-based frameworks is difficulty of formalising realistic
policies using annotations.
Finally, the proposed security-typed LCC is applied to a cloud computing configuration case
study, in which virtual machine migration is managed. The secrecy of LCC interaction models
for virtual machine management is analysed and information leaks are discussed
Early aspects: aspect-oriented requirements engineering and architecture design
This paper reports on the third Early Aspects: Aspect-Oriented Requirements Engineering and Architecture Design Workshop, which has been held in Lancaster, UK, on March 21, 2004. The workshop included a presentation session and working sessions in which the particular topics on early aspects were discussed. The primary goal of the workshop was to focus on challenges to defining methodical software development processes for aspects from early on in the software life cycle and explore the potential of proposed methods and techniques to scale up to industrial applications
Can geocomputation save urban simulation? Throw some agents into the mixture, simmer and wait ...
There are indications that the current generation of simulation models in practical,
operational uses has reached the limits of its usefulness under existing specifications.
The relative stasis in operational urban modeling contrasts with simulation efforts in
other disciplines, where techniques, theories, and ideas drawn from computation and
complexity studies are revitalizing the ways in which we conceptualize, understand,
and model real-world phenomena. Many of these concepts and methodologies are
applicable to operational urban systems simulation. Indeed, in many cases, ideas from
computation and complexity studies—often clustered under the collective term of
geocomputation, as they apply to geography—are ideally suited to the simulation of
urban dynamics. However, there exist several obstructions to their successful use in
operational urban geographic simulation, particularly as regards the capacity of these
methodologies to handle top-down dynamics in urban systems.
This paper presents a framework for developing a hybrid model for urban geographic
simulation and discusses some of the imposing barriers against innovation in this
field. The framework infuses approaches derived from geocomputation and
complexity with standard techniques that have been tried and tested in operational
land-use and transport simulation. Macro-scale dynamics that operate from the topdown
are handled by traditional land-use and transport models, while micro-scale
dynamics that work from the bottom-up are delegated to agent-based models and
cellular automata. The two methodologies are fused in a modular fashion using a
system of feedback mechanisms. As a proof-of-concept exercise, a micro-model of
residential location has been developed with a view to hybridization. The model
mixes cellular automata and multi-agent approaches and is formulated so as to
interface with meso-models at a higher scale
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