Dimosthenis Anagnostopoulos

An Integrated Approach to Automated Semantic Web Service Composition through Planning

The paper presents an integrated approach for automated semantic web service composition using AI planning techniques. An important advantage of this approach is that the composition process, as well as the discovery of the atomic services that take part in the composition, are significantly facilitated by the incorporation of semantic information. OWL-S web service descriptions are transformed into a planning problem described in a standardized fashion using PDDL, while semantic information is used for the enhancement of the composition process as well as for approximating the optimal composite service when exact solutions are not found. Solving, visualization, manipulation, and evaluation of the produced composite services are accomplished, while, unlike other systems, independence from specific planners is maintained. Implementation was performed through the development and integration of two software systems, namely PORSCE II and VLEPPO. PORSCE II is responsible for the transformation process, semantic enhancement, and management of the results. VLEPPO is a general-purpose planning system used to automatically acquire solutions for the problem by invoking external planners. A case study is also presented to demonstrate the functionality, performance, and potential of the approach.

Social media for openness and accountability in the public sector: cases in the Greek context

This paper explores the use of government social media for opennessand accountability. The extant literature has highlighted the benefits of social media use in this context to enhance citizen participation and engagement in decision-making and policy development, facilitate openness and transparency efforts, and reduce corruption. Yet, there are limited studies that discuss those properties of social media that can afford openness and accountability, and their implications for policy and practise. To address these gaps, a study is conducted in the Greek context using interviews with top managers, policy makers, and relevant stakeholders across five initiatives. We discuss distinct affordances for openness and accountability, and propose their inclusion as building blocks of the national ICT policy for openness and accountability. Finally, we provide the implications of the affordances lens for policy and practise, the limitations of the study and future research avenues.

The PORSCE II Framework: Using AI Planning for Automated Semantic Web Service Composition

This paper presents PORSCE II, an integrated system that performs automatic semantic web service composition exploiting AI techniques, specifically planni ng. Essential steps in achieving web service composition include the translation of the web service composition problem into a solver-ready planning domain and problem, followed by the acquisition of solutions, and the translation of the solutions back to web service terms. The solutions to the problem, that is, the descriptions of the desired composite service, are obtained by means of external domain-independent planning systems, they are visualized and finally evaluated. Throughout the entire process, the system exploits semantic information extracted from the semantic descriptions of the available web services and the corresponding ontologies, in order to perform composition under semantic awareness and relaxation.

Model-based system engineering using SysML: Deriving executable simulation models with QVT

Systems Modeling Language (SysML) is used to define hierarchical system models in model-based engineering (MBE). Although SysML may effectively serve the description of complex systems, it can not effectively support all model-based engineering activities. For example, system validation is usually performed via simulation. In this case, SysML system models should be transformed to domain-specific models, e.g. executable simulation models suitable for specific simulation tools. This paper identifies the key issues for efficient SysML model simulation, utilizing Model Driven Architecture (MDA) concepts. The generation of executable simulation code from SysML system models is considered as a model transformation from the SysML meta-model to the simulation meta-model. Since SysML meta-model is defined using Meta-Object Facility (MOF), the definition of MOF simulation meta-models and the utilization of the Query/View/Transformation (QVT) language for model transformations are analytically discussed. The presented approach is not restricted in a specific simulation framework or type. However, in this paper, the experience obtained from a case study on discrete event simulation is evaluated and the conditions that favor the selection of specific simulation frameworks are identified.

A SysML Profile for Classical DEVS Simulators

Discrete event simulation specification (DEVS) is a formalism facilitating hierarchical and modular description of the models executed using DEVS simulators. Lack of standardized, easy-to-use interface enabling simulation practitioners to define their models is an important drawback, since in most cases DEVS models are defined as C++ or Java programs based on existing simulator-specific DEVS libraries. Standard MDA concepts can be applied for the construction of DEVS models executed in different programming environments. DEVS models can be defined using DEVSML, a platform-independent, XML-based format. SysML is proposed as a standardized, graphical representation language of DEVS models stored in DEVSML, consequently transformed into executable code for existing DEVS Simulators, as DEVSJava and DEVSim++. The first step toward this endeavor, is the formal definition of the DEVS SysML profile proposed in this paper.

A Specialized Search Engine for Web Service Discovery

Web service discovery on the web is not a trivial task as the number of available web service descriptions continuously increases, and global UDDI registries are no longer available. As discovery through conventional, general-purpose search engines does not yield satisfactory results, a more promising alternative should be explored through specialized search engines. This paper explores the design and implementation of such a framework, resulting in WESS, a search engine targeted to discovering and retrieving web service descriptions. The presented system features an adaptive web service description collection process, through specialized and directed crawling, as well as an enhanced indexing and retrieval mechanism, which handles description documents as semi-structured text, separating actual information from tags and annotations. The paper also presents experiments and use cases regarding different search scenarios, in addition to performance results.

An integrated framework for automated simulation of SysML models using DEVS

System models are constructed to design, study, and understand complex systems. According to the systems modeling language (SysML) that is a standard for model-based system engineering, all engineering activities should be performed using a common model. To validate complex system models defined in SysML, simulation is usually employed. There are numerous efforts to simulate SysML models using different simulation methods and tools. However, the efficient support of automated generation of executable simulation code is still an issue tangled by the research community. This paper introduces DEVSys, an integrated framework for utilizing existing SysML models and automatically producing executable discrete event simulation code, according to model driven architecture (MDA) concepts. Although this approach is not simulation-specific, discrete event system specification (DEVS) was employed, due to the similarities between SysML and DEVS, mainly in system structure description, and the mature, yet ongoing research on expressing executable DEVS models in a simulator-neutral manner. DEVSys framework elements include (a) a SysML profile for DEVS, enabling integration of simulation capabilities into SysML models, (b) a meta-model for DEVS, allowing the utilization of MDA concepts and tools, (c) a transformation of SysML models to DEVS models, using a standard model transformation language as query/view/transform (QVT), and (d) the generation of DEVS executable code for a DEVS simulation environment with an extensible markup language (XML) interface. The definition and implementation of DEVSys elements, as well as the process for its application are demonstrated and discussed, with the aid of a simple working example.

Handling Non-functional Requirements in Information System Architecture Design

Information system architecture design is a complex task depending on both functional and non-functional requirements. Since system architecture definition is strongly related to system performance, non-functional requirements play a significant role during enterprise information system design. To explore the effect of non-functional requirements on system design process, a model-based approach emphasizing non-functional requirements is proposed. To facilitate the designer to effectively define and handle requirements during architecture design, a number of system views are offered, each of them focusing on discrete design issues and satisfying different kind of requirements. A consistent requirement model is defined representing how non-functional requirements are related between them and to system components forming the overall system architecture. SysML has been adopted as the modeling language, since it enables requirement definition and can be formally extended. Moreover, requirement derivation process is discussed and a case study where the proposed concepts are applied in practice while redesigning the legacy system of a large-scale organization is presented.

Introducing a Public Agency Networking Platform towards Supporting Connected Governance

Connected governance constitutes the current trend regarding the provision of electronic governmental services. In the connected governance paradigm, public agencies share objectives across organizational boundaries, as opposed to working solely supporting autonomous portals in the e-government era. The establishment of connected governance poses new requirements, such as cross-organizational connectivity as well as back-office to front-office integration. Towards supporting this concept, we propose a Public Agency Networking Platform (PANP) facilitating personalized cross-organizational services, based on the concept of life events which represent human situations that trigger public services. The key feature of the platform is the simplification of the process execution workflow, as life events are accomplished through a user orchestrated process combining the functionality of discrete public agency applications. Emphasis has been laid on the citizen data protection by adopting a profile mechanism that enables the citizen to administer his/her own data loaded in his/her profile.

Enterprise Capability Modeling: Concepts, Method, and Application

Strategic alignment among digital services and organizational objectives is crucial for IT, if the enterprise is to use it for competitive advantage. The motivation for the work presented in this paper is based on the need for the design of services that meet the challenges of alignment, agility and sustainability in relation to dynamically changing enterprise requirements. To this end, the paper presents an approach to enterprise modeling that historically has its roots in strategic management and more recently has been considered within the broader spectrum of enterprise architecture, business process management and service-oriented development. We refer to this approach as a capability-centric modeling approach. The paper establishes a framework within which capability modeling would be used in collaboration with other modeling viewpoints and focuses on the specific concepts and techniques that relate to enterprise capability. These concepts and techniques are elaborated upon using a scenario from a leading digital services enterprise.