Papers by George Baryannis
Journal of Applied Logics: The IfCoLog Journal of Logics and their Applications, 2022
Knowledge representation and reasoning in the legal domain has primarily focused on case studies ... more Knowledge representation and reasoning in the legal domain has primarily focused on case studies where knowledge and data can fit in main memory. However, this assumption no longer applies in the era of big data, where large amounts of data are generated daily. This paper discusses new opportunities and challenges that emerge in relation to reasoning with legal big data and the concepts of volume, velocity, variety and veracity. A four-layer legal big data framework is proposed to manage the complete lifecycle of legal big data from sourcing, processing and storage, to reasoning, analysis and consumption. Within each layer, a number of relevant future research directions are also identified, which can facilitate the realisation of knowledge-rich legal big data solutions.
Effective and accurate service discovery and composition rely on complete specifications of servi... more Effective and accurate service discovery and composition rely on complete specifications of service behaviour, containing inputs and preconditions that are required before service execution, outputs, effects and ramifications of a successful execution and explanations for unsuccessful executions. The previously defined Web Service Specification Language (WSSL) relies on the fluent calculus formalism to produce such rich specifications for atomic and composite services. In this work, we propose further extensions that focus on the specification of QoS profiles, as well as partially observable service states. Additionally, a design framework for service-based applications is implemented based on WSSL, advancing state of the art by being the first service framework to simultaneously provide several desirable capabilities, such as supporting ramifications and partial observability, as well as non-determinism in composition schemas using heuristic encodings; providing explanations for unexpected behaviour; and QoS-awareness through goal-based techniques. These capabilities are illustrated through a comparative evaluation against prominent state-of-the-art approaches based on a typical SBA design scenario.
This paper presents a rule-based approach for both offline and real-time recognition of Activitie... more This paper presents a rule-based approach for both offline and real-time recognition of Activities of Daily Living (ADL), leveraging events produced by a non-intrusive multi-modal sensor infrastructure deployed in a residential environment. Novel aspects of the approach include: the ability to recognise arbitrary scenarios of complex activities using bottom-up multi-level reasoning, starting from sensor events at the lowest level; an effective heuristics-based method for distinguishing between actual and ghost images in video data; and a highly accurate indoor localisation approach that fuses different sources of location information. The proposed approach is implemented as a rule-based system using Jess and is evaluated using data collected in a smart home environment. Experimental results show high levels of accuracy and performance , proving the effectiveness of the approach in real world setups.
Service-Oriented Architecture (SOA) has emerged as a prominent design style that enables an IT in... more Service-Oriented Architecture (SOA) has emerged as a prominent design style that enables an IT infrastructure to allow different applications to participate in business processes, regardless of their underlying features, by encapsulating them as platform-independent entities that become available via a certain network, primarily the Internet. In order to effectively discover and use the most suitable services, service description should provide a complete behavior model, describing the inputs and preconditions that are required before execution, as well as the outputs and effects of a successful execution. Such service specifications are indispensable in a variety of activities, such as conformance and verification checks, adaptation evaluation and deducing composability of services.
Service specifications rely on the expression of conditions that should hold before and after service execution. Such specifications are prone to a family of problems, known in the AI literature as the frame, ramification and qualification problems. These problems deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. Research in services has largely ignored these problems, at the same time ignoring their effects, such as compromising the integrity and correctness of services and service compositions and the inability to provide justification for unexpected execution results.
To address these issues, this thesis proposes the Web Service Specification Language (WSSL), a novel, semantics-aware language for the specification and composition of services, independent of service design models. WSSL's foundation is the fluent calculus, a specification language for robots that offers solutions to the frame, ramification and qualification problems. Further language extensions achieve three major goals: realize service composition via planning, supporting non-deterministic constructs, such as conditionals and loops; include specification of QoS profiles; and support partially observable service states.
To investigate WSSL's applicability and demonstrate its benefits, we analyze correctness of the composition extension, decidability and complexity of the underlying theory, as well as compatibility with other related languages in service science. Moreover, an innovative service composition and verification framework is implemented, that advances state-of-the-art by satisfying several desirable requirements simultaneously: ramifications and partial observability in service and goal modeling; non-determinism in composition schemas; dynamic binding of tasks to concrete services; explanations for unexpected behavior; QoS-awareness through pruning and ranking techniques based on heuristics and task-specific goals and an all-encompassing QoS aggregation method for global goals.
Experimental evaluation is performed using synthetically generated specifications and composition goals, investigating performance scalability in terms of execution time, as well as optimality with regard to the produced composite process. The results show that, even in the presence of ramifications in some specifications, functional planning is efficient for repositories up to 500 specifications. Also, the cost of functional discovery per single service is insignificant, hence achieving good performance even when executed for multiple candidate plans. Finally, optimality relies mainly on defining suitable problem-specific heuristics; thus, its success depends mostly on the expertise of the composition designer.
Fluent Calculus-based Semantic Web Service Composition and Verification using WSSL
ABSTRACT We propose a composition and verification framework for Semantic Web Services specified ... more ABSTRACT We propose a composition and verification framework for Semantic Web Services specified using WSSL, a novel service specification language based on the fluent calculus, that addresses issues related to the frame, ramification and qualification problems. These deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. The framework exploits the unique features of WSSL, allowing, among others, for: compositions that take into account ramifications of services; determining the feasibility of a composition a priori; and considering exogenous qualifications during the verification process. The framework is implemented using FLUX-based planning, supporting compositions with fundamental control constructs, including nondeterministic ones such as conditionals and loops. Performance is evaluated with regard to termination and execution time for increasingly complex synthetic compositions.
WSSL: A Fluent Calculus-Based Language for Web Service Specifications
Lecture Notes in Computer Science, 2013
ABSTRACT In order to effectively discover and invoke a Web service, the provider must supply a co... more ABSTRACT In order to effectively discover and invoke a Web service, the provider must supply a complete specification of its behavior, with regard to its inputs, outputs, preconditions and effects. Devising such complete specifications comes with many issues that have not been adequately addressed by current service description efforts, such as WSDL, SAWSDL, OWL-S and WSMO. These issues involve the frame, ramification and qualification problems, which deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. We propose WSSL, a novel specification language for services, based on the fluent calculus, that is expressly designed to address the aforementioned issues. Also, a tool is implemented that translates WSSL specifications to FLUX programs and allows for service validation based on user-defined goals.
Lifecycle management of service-based applications on multi-clouds
Proceedings of the 2013 international workshop on Multi-cloud applications and federated clouds - MultiCloud '13, 2013
ABSTRACT In this paper we identify current challenges in the deployment of complex distributed ap... more ABSTRACT In this paper we identify current challenges in the deployment of complex distributed applications on multiple Cloud providers and review the state of the art in model-driven Cloud software engineering. Challenges include lack of support for heterogeneous Cloud providers; limited matchmaking between application requirements and Cloud capabilities; lack of meaningful cross-platform Cloud resource descriptions; lack of lifecycle management of Cloud applications; inadequate cross-layer monitoring and adaptation based on event correlation; and others. In this paper we propose solutions to these challenges and highlight the expected benefits in the context of a complex distributed application.
Deriving Specifications for Composite Web Services
2012 IEEE 36th Annual Computer Software and Applications Conference, 2012
ABSTRACT We address the problem of synthesizing specifications for composite Web services, starti... more ABSTRACT We address the problem of synthesizing specifications for composite Web services, starting from those of their component services. Unlike related work in programming languages, we assume the definition of the component services (i.e. their code) to be unavailable - at best, they are known by a specification which (safely) approximates their functional behavior. Within this scenario, we deduce general formula schemes to derive specifications for basic constructs such as sequential, parallel compositions and conditionals and provide details on how to handle the special cases of loops and asynchronous execution. The resulting specifications facilitate service verification and service evolution as well as auditing processes, promoting trust between the involved partners.
Two major interrelated issues identified in the fields of service description and service composi... more Two major interrelated issues identified in the fields of service description and service composition:
Service Composition
One of the striking advantages of Web Service technology is the fairly simple aggregation of comp... more One of the striking advantages of Web Service technology is the fairly simple aggregation of complex services out of a library of other composite or atomic services. The same is expected to hold for the domain of Semantic Web Services such as those specified in WSMO or OWL-S. The composition of complex services at design time is a well-understood principle which is nowadays supported by classical workflow and AI planing based composition tools (cf. Chapter 4).
Service Research Challenges and Solutions for the Future Internet
Lecture Notes in Computer Science, 2010
Volume Editors Mike Papazoglou Michael Parkin Tilburg University European Research Institute in S... more Volume Editors Mike Papazoglou Michael Parkin Tilburg University European Research Institute in Service Science (ERISS) 5000 LE Tilburg, The Netherlands E-mail:{mp papazoglou, ms parkin}@ uvt. nl Klaus Pohl Andreas Metzger University Duisburg-Essen Paluno (The ...
2009 33rd Annual IEEE International Computer Software and Applications Conference, 2009
In this work we present "AlertMe", a semanticsbased, context-aware notification system that provi... more In this work we present "AlertMe", a semanticsbased, context-aware notification system that provides personalized alerts to graduate students based on their preferences. An extensive description of the system is carried out. We present the underlying ontology that models the available knowledge, as well as how higher level knowledge inference and context-based decision making is achieved through rule-based reasoning. Finally, we outline the technical aspects of the developed system, covering issues involving the integration of the various subcomponents.
Service-Oriented Architecture has emerged in recent years as a prominent design style that enable... more Service-Oriented Architecture has emerged in recent years as a prominent design style that enables an IT infrastructure to allow different applications to exchange data and participate in business processes, regardless of the underlying complexity of the applications, such as the exact implementation or the operating systems or the programming languages used to develop them. SOAs can be implemented using Web Services, software systems that are designed to support interoperable machineto-machine interaction over a network. In order to effectively find and invoke a Web Service, its provider must provide a complete specification for it. Devising such complete Web Service specifications comes with many issues that need to be solved. This thesis explores the frame problem and its effects in devising Web Service specifications. The frame problem encompasses the issues raised when trying to concisely state in a specification that nothing changes except when explicitly mentioned otherwise. The argument that Web Services are in fact affected by the frame problem is supported by a multi-faceted motivating example that covers both atomic and composite service specifications.
2009 ICSE Workshop on Principles of Engineering Service Oriented Systems, 2009
This work explores the frame problem and its effects in devising Web service specifications. The ... more This work explores the frame problem and its effects in devising Web service specifications. The frame problem encompasses the issues raised when trying to concisely state in a specification that nothing changes except when explicitly mentioned otherwise. A motivating example of a composite service specification is presented and a solution approach is proposed, based on knowledge gained from related research on the frame problem in procedure specifications. Finally, an algorithm that applies the presented solution in order to transform existing OWL-S service descriptions to ones that are free from the frame problem is presented.
In this paper, the design and development of a web database for the purpose of storing and proces... more In this paper, the design and development of a web database for the purpose of storing and processing data produced by a complete building energy analysis is presented. Additionally, a web site that provides access to the database as well as a set of processing functions is outlined. The data stored are read from special input files produced by the TRaNsient SYstems Simulation suite known as TRNSYS. The database and the web site that offers access to it provide safe storage and retrieval of TRNSYS projects while also ...
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Papers by George Baryannis
Service specifications rely on the expression of conditions that should hold before and after service execution. Such specifications are prone to a family of problems, known in the AI literature as the frame, ramification and qualification problems. These problems deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. Research in services has largely ignored these problems, at the same time ignoring their effects, such as compromising the integrity and correctness of services and service compositions and the inability to provide justification for unexpected execution results.
To address these issues, this thesis proposes the Web Service Specification Language (WSSL), a novel, semantics-aware language for the specification and composition of services, independent of service design models. WSSL's foundation is the fluent calculus, a specification language for robots that offers solutions to the frame, ramification and qualification problems. Further language extensions achieve three major goals: realize service composition via planning, supporting non-deterministic constructs, such as conditionals and loops; include specification of QoS profiles; and support partially observable service states.
To investigate WSSL's applicability and demonstrate its benefits, we analyze correctness of the composition extension, decidability and complexity of the underlying theory, as well as compatibility with other related languages in service science. Moreover, an innovative service composition and verification framework is implemented, that advances state-of-the-art by satisfying several desirable requirements simultaneously: ramifications and partial observability in service and goal modeling; non-determinism in composition schemas; dynamic binding of tasks to concrete services; explanations for unexpected behavior; QoS-awareness through pruning and ranking techniques based on heuristics and task-specific goals and an all-encompassing QoS aggregation method for global goals.
Experimental evaluation is performed using synthetically generated specifications and composition goals, investigating performance scalability in terms of execution time, as well as optimality with regard to the produced composite process. The results show that, even in the presence of ramifications in some specifications, functional planning is efficient for repositories up to 500 specifications. Also, the cost of functional discovery per single service is insignificant, hence achieving good performance even when executed for multiple candidate plans. Finally, optimality relies mainly on defining suitable problem-specific heuristics; thus, its success depends mostly on the expertise of the composition designer.