An Object-Oriented Model for Extensible Concurrent Systems: the Composition-Filters Approach

Applying the object-oriented paradigm for the development of large and complex software systems offers several advantages, of which increased extensibility and reusability are the most prominent ones. The object-oriented model is also quite suitable for modeling concurrent systems. However, it appears that extensibility and reusability of concurrent applications is far from trivial. The problems that arise, the so-called inheritance anomalies are analyzed and presented in this paper. A set of requirements for extensible concurrent languages is formulated. As a solution to the identified problems, an extension to the object-oriented model is presented; composition filters. Composition filters capture messages and can express certain constraints and operations on these messages, for example buffering. In this paper we explain the composition filters approach, demonstrate its expressive power through a number of examples and show that composition filters do not suffer from the inheritance anomalies and fulfill the requirements that were established

Brief Announcement: Neighborhood Mutual Remainder and Its Self-Stabilizing Implementation of Look-Compute-Move Robots

In this paper, we define a new concept neighborhood mutual remainder (NMR). An NMR distributed algorithms should satisfy global fairness, l-exclusion and repeated local rendezvous requirements. We give a simple self-stabilizing algorithm to demonstrate the design paradigm to achieve NMR, and also present applications of NMR to a Look-Compute-Move robot system

Dynamic sharing of a multiple access channel

In this paper we consider the mutual exclusion problem on a multiple access channel. Mutual exclusion is one of the fundamental problems in distributed computing. In the classic version of this problem, n processes perform a concurrent program which occasionally triggers some of them to use shared resources, such as memory, communication channel, device, etc. The goal is to design a distributed algorithm to control entries and exits to/from the shared resource in such a way that in any time there is at most one process accessing it. We consider both the classic and a slightly weaker version of mutual exclusion, called ep-mutual-exclusion, where for each period of a process staying in the critical section the probability that there is some other process in the critical section is at most ep. We show that there are channel settings, where the classic mutual exclusion is not feasible even for randomized algorithms, while ep-mutual-exclusion is. In more relaxed channel settings, we prove an exponential gap between the makespan complexity of the classic mutual exclusion problem and its weaker ep-exclusion version. We also show how to guarantee fairness of mutual exclusion algorithms, i.e., that each process that wants to enter the critical section will eventually succeed

Interfacing to Time-Triggered Communication Systems

Time-triggered communication facilitates the construction of multi-component real-time systems whose components are in control of their temporal behavior. However, the interface of a time-triggered communication system has to be accessed with care, to avoid that the temporal independence of components gets lost. This paper shows two interfacing strategies, one for asynchronous interface access (in two variants, one being the new Rate-Bounded Non-Blocking Communication protocol) and one for time-aware, synchronized interface access, that allow components to maintain temporal independence. The paper describes and compares the interfacing strategies.Final Accepted Versio

European Union Social Policy as an Instrument for Sustainable Development

This paper undertakes an analysis and assessment of European Union (EU) social policy in the context of the sustainability of the group's social and economic development. The process of Europeanizing EU social policy is not advanced. Thus, the weight of solving social problems primarily rests with member countries. EU social policy is "looser" in character than other EU policies and its scope is limited to those areas where member states were willing to transfer certain prerogatives to European Union level. The EU only supports social policy in the context of the sustainability of the group's social and economic development. The process of Europeanizing EU social policy is not and supplements the actions of member states in the social sphere. At the same time, the EU supports the concept of corporate social responsibility. Corporate social responsibility is defined as the voluntary taking into account by companies of social and environmental matters in their operations and in relations with interested parties.W artykule została przeprowadzona analiza i ocena polityki społecznej Unii Europejskiej (UE), w kontekście równoważenia rozwoju społeczno-gospodarczego ugrupowania. Proces europeizacji polityki społecznej UE nie jest zaawansowany. W związku z tym, ciężar rozwiązywania problemów społecznych spoczywa głównie na krajach członkowskich. Polityka społeczna UE ma bardziej "luźny" charakter niż inne polityki UE i jej zakres jest ograniczony do tych dziedzin, w zakresie których kraje członkowskie były skłonne do przekazania pewnych uprawnień na szczebel unijny. UE jedynie wspiera i uzupełnia działania państw członkowskich w sferze społecznej. Jednocześnie UE wspiera ideę społecznej odpowiedzialności przedsiębiorstw. Społeczną odpowiedzialność przedsiębiorstw definiuje się jako dobrowolne uwzględnienie przez przedsiębiorstwa problematyki społecznej i ekologicznej w swojej działalności i stosunkach z zainteresowanymi stronami