Model of error propagation in systems of communicating processes

AbstractThe subject of the present paper is the error propagation model for systems of communicating processes in distributed computer systems. This has been used to express a new idea about an error recovery method in a system of processes which does not need any limitation on communication. It has been assumed that the technique of error recovery is based on state restoration, and that the recovery function is implemented in a distributed way. The notion of recovery line and a method for its construction have been discussed. Next it has been argued that the recovery function should be implemented as a protocol

Bezpieczeństwo hydrologiczne w perspektywie Chińskiej Republiki Ludowej

Today’s China is the world’s biggest economy. Economy and population growth has impact on Chinese water resources. Pollution and water waste are decreasing the supply of clean water. Besides, there are areas like the southern and eastern regions of China that receive abundant rainfall while the northern and western regions receive much lower rainfall. Government must provide water for drinking purposes and for economy. This isn’t an easy task. Measures that solve one problem often create another one

Flexible Organization of Repositories for Provisioning Cloud Infrastructures

The paper proposes an architecture of a system automating the provisioning process of cloud computing infrastructures. Its structure and components are specified, based on an analysis of three types of requirements: infrastructure providers, service providers and end users. These considerations have led us to formulate a new infrastructural model, offered to end users as a collection of Virtual Machines (VM) connected by a dedicated Virtual Private Network (VPN) with QoS guarantees. The role of repositories in cloud provisioning systems is specified along with the relevant data acquisition processes. The applicability of the proposed system is illustrated by practical usage scenarios

Adaptable Service Oriented Infrastructure Provisioning with Lightweight Containers Virtualization Technology

Modern computing infrastructures should enable realization of converged provisioning and governance operations on virtualized computing, storage and network resources used on behalf of users' workloads. These workloads must have ensured sufficient access to the resources to satisfy required QoS. This requires flexible platforms providing functionality for construction, activation and governance of Runtime Infrastructure which can be realized according to Service Oriented Infrastructure (SOI) paradigm. Implementation of the SOI management framework requires definition of flexible architecture and utilization of advanced software engineering and policy-based techniques. The paper presents an Adaptable SOI Provisioning Platform which supports adaptable SOI provisioning with lightweight virtualization, compliant with the structured process model suitable for construction, activation and governance of IT environments. The requirements, architecture and implementation of the platform are all discussed. Practical usage of the platform is presented on the basis of a complex case study for provisioning JEE middleware on top of the Solaris 10 lightweight virtualization platform

Evolution of Reactive Streams API for Context-Aware Mobile Applications

This article describes the role of reactive streams concept as a core communication pattern in mobile-first applications and proposes directions for evolution of its classic API to better match mobile application requirements. By designing the selected examples of mobile applications, the authors evaluate the Reactive Streams API which is an increasingly accepted standard for asynchronous communication with back-pressure. This design is then assessed with regard to solution expressiveness and the ability to satisfy functional and non-functional requirements of the stated problems. It is observed that the used API does not allow for a context propagation from a mobile subscriber to a publisher so that the streamed data can be well adjusted to the variable reception context of a given mobile device. To address this issues, a context-aware variant of this API is proposed and it is demonstrated and discussed by presenting an alternative application design

Virtual Grid - New Paradigm of System Resources Dynamic Organization

This paper describes the model and software tools for virtualization of the Grid execution environment. The basic assumption of this study is that Virtual Grid (VG) is constructed dynamically according to application requirements with virtualized computational and communication resources. A VG instance is dynamically created for each application and its initial configuration can be further modified during runtime to satisfy the requested level of resource usage and to maintain the quality of service indexes at agreed-upon values. A VG model that takes into account this approach has been proposed and analyzed in the context of Grid-related technology

Zastosowanie cementu zawierającego fosforan wapnia do wertebroplastyki podstawy zęba kręgu obrotowego

The authors describe the use of bone cement containing calcium phosphate for vertebroplasty of the cavity in the base of odontoid process. A 23-year-old female patient was operated on by incision in lateral cervical area (anterior open access). After a blunt dissection, the working cannula (Kyphon) was introduced under fluoroscopic guidance through the C2 vertebral body to the cavity in the base of the odontoid process. Intraoperatively biopsy of the lesion was taken and histopathological examination excluded the presence of neoplasm. The cavity, presumably haemangioma, was successfully filled with calcium phosphate bone cement KyphOs™ FS (Kyphon). The proper filling without paravertebral cement leak was confirmed by postoperative computed tomography (CT). The CT and magnetic resonance imaging performed 9 months after the procedure showed that cement was still present in the cavity. This is the first use of calcium phosphate cement to conduct the vertebroplasty of C2 vertebra.Autorzy opisują zastosowanie cementu zawierającego nieorganiczne sole fosforanu wapnia do wertebroplastyki podstawy zęba kręgu C2. Zabieg wykonano u 23-letniej pacjentki. Przez kilkucentymetrowe nacięcie skóry w prawej okolicy bocznej szyi (otwarty dostęp przedni) do trzonu C2 wprowadzono w linii pośrodkowej kaniulę roboczą (Kyphon). Przez kaniulę pobrano materiał do badania histopatologicznego. Po wykluczeniu obecności komórek nowotworowych, do jamistej strefy na granicy trzonu i zęba kręgu obrotowego, określonej jako naczyniak, podano cement KyphOs™ FS (Kyphon). Pooperacyjna tomografia komputerowa (TK) potwierdziła całkowite wypełnienie jamy oraz kanału wytworzonego przez kaniulę; cement nie wydostał się poza kręg C2. Wykonane po 9 miesiącach TK i obrazowanie za pomocą rezonansu magnetycznego potwierdziły obecność cementu w miejscu podania. Jest to pierwsze zastosowanie cementu zawierającego fosforan wapnia do wertebroplastyki w obrębie kręgu C2