Vassilis Kapsalis

A dynamic context-aware access control architecture for e-services

The universal adoption of the Internet and the emerging web services technologies constitutes the infrastructure that enables the provision of a new generation of e-services and applications. However, the provision of e-services through the Internet imposes increased risks, since it exposes data and sensitive information outside the client premises. Thus, an advanced security mechanism has to be incorporated, in order to protect this information against unauthorized access. In this paper, we present a context-aware access control architecture, in order to support fine-grained authorizations for the provision of e-services, based on an end-to-end web services infrastructure. Access permissions to distributed web services are controlled through an intermediary server, in a completely transparent way to both clients and protected resources. The access control mechanism is based on a Role-Based Access Control (RBAC) model, which incorporates dynamic context information, in the form of context constraints. Context is dynamically updated and provides a high level of abstraction of the physical environment by using the concepts of simple and composite context conditions. Also, the paper deals with implementation issues and presents a system that incorporates the proposed access control mechanism in a web services infrastructure that conform to the OPC XML-DA specification.

Architecture for Web-based services integration

Industrial applications and systems still lack in adopting the Web Services architecture. Legacy systems, either OPC-based or proprietary ones, compose a huge source of data, which can be migrated and integrated into enterprise-level information systems. Within the context of prevailing and emerging technologies, such as HTTP, XML, SOAP, OPC and Web-enabled application servers, we propose an architecture that allows for the integration of existing stand-alone industrial automation systems into Web-based distributed environments, forming the base for the provision of large-scale e-services by a multitude of service providers to industrial-type clients.

OPC-SMS: a wireless gateway to OPC-based data sources

This paper describes OPC-SMS gateway, a platform that integrates IP networks with the Short Message Service (SMS), in order to deliver an integrated service for access to data sources conforming to Object Linking and Embedding for Process Control (OPC) standard specifications, through SMS-enabled mobile devices. The gateway supports pull and push services in order to support both request-based and alarm/scheduled-based notifications, respectively. The proposed architecture is based entirely on the ubiquitous HyperText Transport Protocol (HTTP), Simple Object Access Protocol (SOAP), Extensible Markup Language (XML) protocols, and the Global System for Mobile communication (GSM) network and thus exploits the network infrastructure already in place. The capability of accessing different types of OPC data sources (real-time and historical) by any SMS-enabled device consists of a highly flexible service, supporting mobility and event-based notification. A pilot implementation of our approach has been tested in a large-scale installation for accessing OPC data sources of several automation subsystems in a hospital.

Web gateway: a platform for industry services over Internet

This paper presents a novel approach for the integration of industrial applications over LANs, WANs and the Internet, based on emerging proven and robust technologies. Industrial applications are traditionally viewed with reference to a four layer hierarchical model. Fieldbus control networks are used in order to interconnect field and control devices at the two lower layers of the industrial communication hierarchy. The OPC technology is utilized in order to provide a universal I/O driver/interface for heterogeneous control networks. Different OPC objects deal with real time data (OPC DA), historical data (HDA) as well as Alarms and Events. DCOM presents the middleware connectivity software for the seamless integration of applications locally over the LAN. Due to the DCOM lack in firewall friendliness, the authors propose the use of pure HTTP and the development of a special entity, the Web Gateway, that presents a single point of entry for all different users, e.g. service providers, for the provision of integrated services in a uniform way. This gateway takes into account user profiles and utilizes a dynamic parser for the generation of dynamic html according to user rights. The presented architecture has been the core of a pilot implementation.

Seamless integration of distributed real time monitoring and control applications utilising emerging technologies

The seamless integration of distributed real time applications is mandatory for such demanding environments as the industrial environment or building management systems. Several technologies presenting different degrees of maturity have been developed to support this goal. The paper presents work done at the Industrial Systems Institute, which resulted in the definition of a system architecture utilising different emerging technologies, and its pilot implementation.

Integrating IP traffic into fieldbus networks

Fieldbus networks are traditionally used in order to interconnect devices at the field level e.g. sensors and actuators, so that real time or critical time requirements are met concerning data transfer. In addition to traditional fieldbus traffic, novel applications, such as industrial multimedia applications, require the integration of IP traffic into fieldbus networks as well. This integration should be done so that the usual control traffic is not inhibited in any way by IP traffic, while on the other hand specific Quality of Service requirements are met by IP traffic. This paper deals with the different problems that are relevant to the integration of IP traffic into fieldbus networks. It focuses especially on the IP Mapper layer that need to be incorporated between the TCP/IP Stack and the Fieldbus Data Link Layer and performs the appropriate conversion of IP datagrams into fieldbus datagrams as well as the integration of the TCP/IP and the fieldbus communication models. Finally, it presents the way that these problems have been addressed for the integration of IP traffic over a specific fieldbus network.

A networking platform for real-time monitoring and rule-based control of transport fleets and transferred goods

This paper presents a networking platform which provides real-time monitoring and rule-based control of transport fleets and transferred goods. Special emphasis is given in providing tools and services to fleet administrators, which, among others, comprise an object oriented rule detection mechanism based on the occurrence of predefined events which are fully configurable and are considered important for the freight transport management of dangerous goods. Conceptual and architectural design decisions considering interoperability, reusability, security and modularity issues are presented. Finally, as a proof of concept, a case study is presented in which the proposed platform has been applied to a commercial fleet of fuel and lubricant tank trucks.

Optimal scheduling of smart homes' appliances for the minimization of energy cost under dynamic pricing

This paper focuses on the development of load scheduling algorithms applied to representative types of home appliances, in order to reduce the energy cost, in a context of fluctuating energy prices, based on users requirements. The presented algorithms could be executed both in a centralized energy management system and in distributed low-cost load controllers. Respective analysis and evaluation provide significant insight, both concerning feasibility and flexibility of such approaches as well as potential cost reduction.

Edu-Smile: a context-aware service for synchronous support in Web-based educational systems

In this paper a context-aware service for synchronous support in Web-based educational systems is proposed. The main purpose of the service is to support Web-based learning scenarios by allowing synchronous communication and interaction among the tutors and the students, thus increasing the communication channels among them. Furthermore, the service provides a variety of tools that allows the tutors to provide real-time support to the students, discover usability and navigability problems and monitor their actions while they interact with the Web-based educational environment.

Towards a domain‐specific context acquisition, presentation and rule‐based control platform

Purpose – Research on context‐aware systems design has received significant attention lately. One of the research directions on context‐aware systems is towards context‐aware frameworks adapted to domain‐specific requirements, aiming to improve their applicability in a variety of applications, which share common requirements. The purpose of this paper is to present the design of a domain‐specific context‐aware platform supporting context acquisition, presentation and rule‐based control.Design/methodology/approach – The proposed platform uses a formal context model, based on ontologies description, aiming to provide a common representation of contextual information, facilitating thus integration and reusability in application domains, which embrace a common set of requirements. A context‐aware system has been built upon a well defined data model, which inherits a list of offered functionalities and/or services at the acquisition, presentation and reasoning level. The presented platform entails an event‐dri...