Electronic Communications of the EASST (European Association of Software Science and Technology)
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Preface of the Post-proceedings of the 8th International Workshop on Graph Transformation and Visual Modeling Techniques
No full textAn Architecture to Support Learning-based Adaptation of Persistent Queries in Mobile Environments
Get PDFQueries are frequently used by applications in dynamically formed mobile networks to discover and acquire information and services available in the surrounding environment. A number of inquiry strategies exist, each of which embodies an approach to disseminating a query and collecting results. The choice of inquiry strategy has different tradeoffs under different operating conditions. Therefore, it is beneficial to allow a query-based application to dynamically adapt its inquiry strategy to the changing environmental conditions. To promote development by non-expert domain programmers, we can automate the decision-making process associated with adapting the inquiry strategy. In this paper, we propose an architecture to support automated adaptative query processing for dynamic mobile environments. The decision-support module of our architecture relies on an instance-based learning approach to support context-aware adaptation of the inquiry strategy
Language Abstractions for RFID Technology
Get PDFDeveloping pervasive and context-aware applications that make use of RFID technology is a daunting task given the high degree of failures inherent to communication with RFID tags. The reason is that current programming models do not incorporate these failures into the very heart of their computational model. AmbientTalk, a research language aimed at pervasive applications running in mobile ad hoc networks, does offer such a programming model, but it is aimed at mobile devices interconnected via peer-to-peer network connections such as WiFi or Bluetooth. In this paper we show how we use this programming model for the communication with RFID tags
Migrating Legacy Systems to Service-Oriented Architectures
Get PDFThis paper presents a methodology for migrating legacy systems towards Service-Oriented Architectures. The approach is based on source code analysis for identifying the contribution of code fragments to architectural elements and graph transformation for architectural migration, allowing for a high degree of automation. In order to transform existing application architectures into SOAs, the methodology has to be used in two dimensions, a technological and functional one.
The work presented here is being developed in the context of a collaboration between academia and industry, and is aimed at being applied in real reengineering projects
Contraction of Unconnected Diagrams using Least Cost Parsing
Get PDFA free-hand diagram editor allows the user to place diagram components on the pane without any restrictions. This increase in flexibility often comes at the cost of editing performance, though. In particular it is tedious to manually establish the spatial relations between diagram components that are required by the visual language. Even worse are certain graph-like languages where it is a quite annoying task to explicitly link the node components.
In this paper diagram contraction is proposed for solving these issues. The editor user can just roughly arrange a set of diagram components. On request the editor automatically creates a correct diagram from these components while preserving their layout as far as possible. Moreover, for several languages diagram contraction corresponds to linking node components appropriately. Such auto-linking is considered useful. It even has been integrated into first commercial modeling tools.
The proposed approach can be applied to visual languages that are specified by means of hypergraph grammars. For syntax analysis an error-tolerant hypergraph parser is used, which computes a cost function by attribute evaluation. That way, unfavorable derivation (sub-)trees can be excluded at an early stage, and combinatorial explosion is mostly prevented
A workbench for preprocessor design and evaluation: toward benchmarks for parity games
Get PDFWe describe a prototype workbench for the study of parity games and their solvers. This workbench is aimed at facilitating two activities: to aid in the design, validation, and evaluation of preprocessors for parity game solvers; and to aid in the generation of benchmark parity games that are meaningful for a wide range of solvers. Our workbench allows for easy composition of preprocessors, can populate databases with games and their meta-data, offers a query language for generating games of interest, and has already found potentially hard games
On the Modelling of an Agent's Epistemic State and its Dynamic Changes
Get PDFGiven a set of unquantified conditionals considered as default rules
or a set of quantified conditionals such as probabilistic rules, an
agent can build up its internal epistemic state from such a knowledge
base by inductive reasoning techniques. Besides certain (logical) knowledge,
epistemic states are supposed to allow the representation of preferences,
beliefs, assumptions etc. of an intelligent agent. If the agent lives in
a dynamic environment, it has to adapt its epistemic state constantly to
changes in the surrounding world in order to be able to react adequately
to new demands. In this paper, we present a high-level specification of
the Condor system that provides powerful methods and tools for managing
knowledge represented by conditionals and the corresponding epistemic
states of an agent. Thereby, we are able to elaborate and formalize
crucial interdependencies between different aspects of knowledge
representation, knowledge discovery, and belief revision. Moreover,
this specification, using Gurevich's Abstract State Machines, provides
the basis for a stepwise refinement development process of the Condor
system based on the ASM methodology
Generating Correctness-Preserving Editing Operations for Diagram Editors
Get PDFIn previous work it has already been shown that syntax-directed and free-hand editing can be gainfully integrated into a single diagram editor. That way, the user can arrange diagram components on the screen without any restrictions in free-hand editing mode, whereas syntax-directed editing operations provide powerful assistance. So far, editing operations had to be specified or programmed by the editor developer. In contrast, this paper proposes an approach where diagram-specific editing operations are generated on the fly during the editing process and without any additional specification effort. These operations provably preserve the correctness of the diagram. The proposed approach requires a specification of the visual language by a hypergraph grammar
Modelling Clustering of Wireless Sensor Networks with Synchronised Hyperedge Replacement
Get PDFThis paper proposes Synchronised Hyperedge Replacement (SHR) as a suitable modelling framework for Wireless Sensor Networks (WSNs). SHR facilitates explicit modelling of WSNs applications environmental conditions (that significantly affect applications performance) while providing a sufficiently high level of abstraction for the specification of the underling coordination mechanisms. Because it is an intractable problem to solve in distributed manner, and distribution is important, we propose a new Nutrient-flow-based Distributed Clustering (NDC) algorithm to be used as a working example. The key contribution of this work is to demonstrate that SHR is sufficiently expressive to describe WSNs algorithms and their behaviour at a suitable level of abstraction to allow onward analysis
Systematically Engineering Self-Organizing Systems: The SodekoVS Approach
Get PDFSelf-organizing systems promise new software quality attributes that
are very hard to obtain using standard software engineering approaches. In accordance
with the visions of e.g. autonomic computing and organic computing,
self-organizing systems promote self-adaptability as one major property helping to
realize software that can manage itself at runtime. In this respect, self-adaptability
can be seen as a necessary foundation for realizing e.g. self* properties such as self-configuration or self-protection. However, the systematic development of systems
exhibiting such properties challenges current development practices. The SodekoVS
project addresses the challenge to purposefully engineer adaptivity by proposing a
new approach that considers the system architecture as well as the software development
methodology as integral intertwined aspects for system construction. Following
the proposed process, self-organizing dynamics, inspired by biological, physical
and social systems, can be integrated into applications by composing modules
that distribute feedback control structures among system entities. These compositions
support hierarchical as well as completely decentralized solutions without a
single point of failure. This novel development conception is supported by a reference
architecture, a tailored programming model as well as a library of ready to use
self-organizing patterns. The key challenges, recent research activities, application
scenarios as well as intermediate results are discussed