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Abstract. Today, one can observe an ever increasing trend in the use of mobile systems. This change inevitably affects the software running on such devices by necessitating additional functionality such as context awareness and adaptive behavior. While some developers design their systems to be fully self-reliant with regard to context awareness, others aim for more synergistic approaches by allowing context sharing across devices. This paper describes our experience with first designing and implementing a basic context management system, and then with extending it to allow context distribution. In the proposed architecture, the developers define the context dependencies for their software independently of the availability of context information in their corresponding devices. An automated mechanism is then used to match these needs to the corresponding providers, even when those reside across distributed devices. This approach enables them to utilize shared context information at runtime thus reducing both development efforts and hardware costs.

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The rapid growth of telecontrol systems is one of the major trends in today's network-oriented community. The implementation of generic frameworks, consisting of reusable components that can form the basis for the development of such systems, is a necessity. There is a plethora of associated applications that can be developed in a distributed environment, such as audio/video teleconferencing, groupware and collaborative computing environments, remote controlled services, etc. In this paper we design and implement a generic framework of components that can be used for the realization of telecontrol applications. This category of applications focuses primarily on the issues of managing distributed units on remote end-systems. Such applications contain remote units and administrators that are connected and exchange data and control messages. We analyse the outlined architecture of our framework and the most important system operations. We also describe the communication protocol used in message exchanges between the constituent components. Finally, we illustrate the usefulness of our framework by presenting two applications that were created by extending the basic software infrastructure.the extent that dependencies between system components cannot be neglected. This necessitates the presence of frameworks to provide a methodology for integrating different components and assisting in the rapid development of so-called telecontrol applications. Although it is impossible in general to implement a generic framework for all types of applications, we would like to have available more focused frameworks for specific domains of distributed applications, comprising reusable components, which can then be used to 'instantiate' specific applications. In this paper we analyse the basic concepts of telecontrol systems; most of the applications in this domain focus on the notion of 'controlling and monitoring units'.A typical telecontrol system provides complete and remote automatic control of the devices comprising it. It collects data, manages alarms and signals from the involved devices and, often, reconfigures remotely the latter. Such systems are very useful in areas which are difficult to access or in cases where it is not possible or desirable to have local staff. The architecture of a telecontrol system is simpler than that of a general purpose distributed control system (DCS) and can be seen as comprising a set of administrator units managing a set of remote devices. Typical telecontrol environments can be seen in holiday homes, caravans, boats, private homes and real estates. Typical telecontrol functionality includes the monitoring of various machines, passage control, tele-measuring, reading of gas, electricity and water consumption, etc. Currently, these applications are becoming increasingly popular, covering a range of domains beyond the house automation installations. In agriculture, for example, telecontrol applications are used for handling temperature and humidity alarms in corn fields, feeding machines in fish...