Marek Woda

Relation-based Message Routing in Wireless Sensor Networks

Sensor networks and their related topics represent some of the greatest and challenging possibilities in the research field that have come about in recent years. Emerging technologies like wireless sensor network (WSN), standards enabled legacy sensors, ubiquitous and cloud computing, middleware, communication systems, internet protocols (IP) and next generation networks are leading to a set of new paradigms where wireless sensors can be treated as vital components of common infrastructure and a shared resource with an ability to serve multiple and concurrently executing applications run by various users in distributed environment. This is in strong contrast to traditional concepts where dedicated sensor devices are being physically and logically hard-wired to communication and computing infrastructure serving very specific and dedicated data/information processing applications. Wireless sensor networks consist of a number of small electronic devices (nodes) distributed in an area that by far exceeds the communication range of a single sensor. Message routing is one of the most important issues in such networks. This is mainly due to the large number of nodes, variety of possible communication paths, restricted power source and variability (in time and space) of environmental conditions in which the WSN operates. A shared communication channel and restricted communication ranges require that nodes of the WSN cooperate and/or coordinate their actions while messages are routed from nodes to the base station (BS). It is a well-known idea Descartes & Lafleur (1960) to solve large and complex problems by dividing them into smaller and possibly simpler tasks. The most crucial element of such an attempt is to decide how to divide the problem in order to get a problem that can be solved efficiently and, what is more important, can be used to find a solution to the original problem. A distributed system, such as a WSN, is traditionally seen as a set of spatially distributed nodes that communicate, coordinate their actions and inform other nodes about their status using special messages sent over the communication channel Dollimore et al. (2005). Such a system is usually assumed to be isolated from the outside word – even if it measures its parameters and/or listens to the status messages from other nodes, it is still not affected by the environmental conditions and its changes. We are going to look at such a system as it 7

Evaluation of SOA Security Metrics Using Attack Graphs

First, different security metrics are presented. A proposal of risk assessment for service oriented architecture (SOA) is given. This proposal is based on service availability metrics. First metric represents costs (extend of damage), when the service is not available. The second one is a probability that the service is available. Foundations for calculating this probability by simulation using attack graphs are given. The attack graph is a representation of actions that end in a state where an intruder achieved his/her goal. A model of intrusion detection system is given too.

Proposal of Cost-Effective Tenant-Based Resource Allocation Model for a SaaS System

Software-as-a-Service (SaaS) is a software distribution paradigm in cloud computing and represents the highest, software layer in the cloud stack. Since most cloud services providers charge for the resource use it is important to create resource efficient applications. One of the ways to achieve that is multi-tenant architecture of SaaS applications. It allows the application for efficient self-managing of the resources. In this paper the influence of tenant-based resource allocation model on cost-effectiveness of SaaS systems is investigated. The tenant-based resource allocation model is one of the methods to tackle under-optimal resource utilization. When compared to traditional resource scaling it can reduce the costs of running SaaS systems in cloud environments. The more tenant-oriented the SaaS systems are the more benefits that model can provide.

Conception of Composing Learning Content into Learning Tree to Ensure Reliability of Learning Material

The aim of this paper is to introduce a conception of the easy, robust and reliable computer aided composition teaching material into one learning tree, which constitute the basis for an e-education system. . It is also presented a simplified schema of lessons positioning in the Z-plane of the learning tree. Author also focuses on the diversification of difficulty levels corresponding to the particular e-lesson version to be suitable for a certain type of student

Directed Communication in Wireless Sensor Network Based on Digital Terrain Model

This paper presents a method of directed information transmission for Wireless Sensors Network based on Digital Terrain Model. Using network of irregular triangles and Delaunay’s triangulation algorithm a drainage function is constructed that covers all routing paths from nodes to the base station. Drainage function describes a set of points in 3D space and is a composition of several surfaces. There are two basic surfaces, first is fixed and related to the natural network topology features, second is variable and represents energy cost of a communication activity. Additional surfaces, that enable to model different kind of message routing strategies, are proposed for future work. Our proposal allows to shape the drainage function through modification of collision, subordination and tolerance coefficients that upheaval, lower and draw aside the surface respectively, leading to different communication activities.

Analysis of Timing Requirements for Intrusion Detection and Prevention using Fault Tree with Time Dependencies

In-depth analysis of an attack strategy enables possibility to prevent it or when it is inevitable to minimize its adverse effects. Intrusion detection systems (IDS) base their operation on the built-in patterns of various attack strategies. Aforementioned strategies can be represented by different means like: augmented goal-tree [6], attack trees [17] (originated from on fault trees), attack graphs [14], or augmented software fault trees [4]. In augmented goal tree representation [6], the attack is expressed by sequences of logically related steps. The root of this tree is the goal of the attack, e.g., “Modification of a file”. The sub-goals are associated with the roots of the sub-trees. The basic constructs are the OR, AND, Ordered-AND constructs. For example, in order to achieve the sub-goal represented as the root of the Ordered-AND construct, all sub-sub-goals have to be reached in required order. Fault tree analysis (FTA) [3], which is a base of the attack tree [17] analysis, is a deductive probabilistic assessment technique. The FTA is the backward approach. In the fault tree, the root is associated with the top event being the hazard, e.g. “The Intrusion takes control over the Victim”. Then direct causes of the hazard are considered. Next, the causes of the above causes are analyzed. Hence, different ways in which the hazard can occur are investigated. The FTA can be used to determine the following: minimal cut sets of faults that cause a hazard, probabilities of the hazard and faults. Therefore, the FTA can be used in identification which events are critical and should therefore be subjected to monitoring. Traditional Fault Trees (FT) are widely criticized [14] due to many, widely known drawbacks, like inability to model multiple attack attempts, time dependencies, or access controls as well as for luck of modeling cycles. In the attacks graphs [14], nodes symbolize the class of machines the attacker accessed and as well user level of privileges. The arcs are labeled by attackers’ activities. By assigning probabilities of success on the arcs, one can identify the attack paths with the highest probability of success. Augmented software fault trees [4] were defined in order to overcome disadvantages of the classical fault trees. In this approach, a trust, a context, and temporal orderings can be defined. The trust relationship expresses that some members of a distributed system trust other members of the system. Context describes which subsets of intrusive events occur in

Dependability Aspects of e-Learning Systems

This work is devoted to dependability analysis of e-learning systems. Authors present technical aspects of the software part of e-learning systems (e-learning platforms, distant lectures, multimedia presentations and virtual laboratories). Next, a high availability approach to hardware part is discussed. It is followed by a short analysis of several dependability aspects (availability, usability, scalability, interoperability, stability and security) with a conclusion that business continuity is a crucial factor. Therefore, the analysis of the e-learning system monitoring techniques is given. It is followed by a proposition of a new technique of monitoring: the virtual user representative.

Dependability Evaluation of Service-oriented Information System Using Computer Simulation and Post-processing Results

In times of known hacking techniques as well as malicious software ubiquity, mostly commercialized information systems are seriously threaten. For this reason nowadays network security and dependable operation has become a major priority for design and implementation. Looking for powerful means network engineers started to often use computer simulation technique as a way for better understanding and development of complex computer systems. Therefore, plenitude of specialized development initiatives appeared in last few years. Currently network simulators are tools useful not only for creating new and better protocols, but also become money savers. By extending their functionalities e.g. post-processing capabilities for evaluating security and dependability metrics they turn out to be a fundamental state of the art network management platforms. This paper presents the information system, proposes metrics definitions, and describes the procedure of their evaluation using a simulator and a post-processing module.

Performance Aspect of SaaS Application Based on Tenant-Based Allocation Model in a Public Cloud

The main aim of current study was to check performance of tenant-based vs. tenant-unaware resource allocation model of SaaS application in a public Cloud. In order to do so, two SaaS systems were developed. First of them used traditional resource scaling based on number of users. It acted as a reference point for the second system. Previously conducted tests were primarily focused on measuring over- and underutilization in order to compare cost-effectiveness of the solutions. The tenant-based resource allocation model proved to decrease system’s running costs. It also reduced the system’s resources underutilization. Similar research was done, but the model was tested in a private cloud. In this paper the systems were deployed into a commercial public cloud and performance aspects were scrutinized.

Wireless sensors network simulator for modeling relation based communication activity

The paper presents a simulator that models routing paths and energy distribution in a WSN as a function of the algorithm executed by each node of the network. Simulator was prepared to investigate whether globally defined goals can be achieved through the decisions and actions taken locally by each node that has restricted information about the whole network. Therefore, simulator models each node independently defining three basic relations for each of them - subordination, tolerance and restriction. We have implemented several novel, non-clustered routing protocols that describe behavior of each node of the network - so that we are able to verify how decisions taken locally affect the whole network.