Institut für Informatik
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In this work, some network protocols with Wireshark Protokollanalyser should be observed and described the deal with them. Wireshark is an offshoot of "Ethereal", one of the most popular protocol analyzer. Wireshark analysis network traffic, draws on it and make it clear . For the simulation of the network is used VNUML. Since VNUML can only be used under Linux, andLinux is running as a virtual machine in between to work in Windows to be able to.
This thesis presents an analysis of API usage in a large corpus of Java software retrieved from the open source repositories hosted at SourceForge. Most larger software projects use software libraries, which offer a public "application programming interface" or API as an interface for the programmer. In order to facilitate the transition between different APIs, there are emerging research projects in the field of automated API migration. However, there is a lack of basic statistical background information about in-the-wild usage of APIs as such measurements have, until now, only been done on rather small corpora. We thus present an analysis method suitable for measurements with large corpora. First, we create a corpus of open source projects hosted on SourceForge, as well as a corpus of software libraries. Then, all projects in the corpus are compiled with an instrumented compiler. We use a compiler plugin for javac that gives detailed information about every method created by the compiler. This information is stored in a database and analyzed.
Knowledge compilation is a common technique for propositional logic knowledge bases. A given knowledge base is transformed into a normal form, for which queries can be answered efficiently. This precompilation step is expensive, but it only has to be performed once. We apply this technique to concepts defined in the Description Logic ALC. We introduce a normal form called linkless normal form for ALC concepts and discuss an efficient satisability test for concepts given in this normal form. Furthermore, we will show how to efficiently calculate uniform interpolants of precompiled concepts w.r.t. a given signature.
In einer Welt, die immer mehr durch den Einsatz von Technik geprägt wird, gewinnen Systeme, welche eigenständig Aufgaben in einem vorgegebenen Kontext übernehmen können, mehr und mehr an Bedeutung. Solche Systeme werden als autonome Systeme bezeichnet, die ein eigenständiges Verhalten und Interaktionen mit ihrer Umwelt und anderen Systemen beinhalten. Zu diesen Systemen zählen auch autonome mobile Roboter. Sie sind sozusagen intelligente Fahrzeuge, die ihnen übertragene Aufgaben ohne menschliche Unterstützung durchführen können. Um ihre Umwelt wahrzunehmen, mit ihr interagieren und in ihr navigieren zu können benötigen diese Systeme verschiedene Arten von Sensoren. Somit ist die Robotikforschung stark interdisziplinär. Diese Arbeit befasst sich ausschliesslich mit dem Bereich der Navigation, insbesondere mit der Positionsbestimmung, welche für eine gute Navigation die Grundlage bildet. Ein heutzutage häufig benutztes, weltweit verfügbares System zur Positionsbestimmung ist GPS. Ziel dieser Arbeit ist der Anschluss eines GPS-Moduls an einen Mikrocontroller und der Versuch die Positionsgenauigkeit lokal zu präzisieren, um so einem autonomen System die Möglichkeit zur eröffnen, Aufgaben, die eine höhere Genauigkeit erfordern, zu bewerkstelligen.
The processing of data is often restricted by contractual and legal requirements for protecting privacy and IPRs. Policies provide means to control how and by whom data is processed. Conditions of policies may depend on the previous processing of the data. However, existing policy languages do not provide means to express such conditions. In this work we present a formal model and language allowing for specifying conditions based on the history of data processing. We base the model and language on XACML.
Hybrid automata are used as standard means for the specification and analysis of dynamical systems. Several researches have approached them to formally specify reactive Multi-agent systems situated in a physical environment, where the agents react continuously to their environment. The specified systems, in turn, are formally checked with the help of existing hybrid automata verification tools. However, when dealing with multi-agent systems, two problems may be raised. The first problem is a state space problem raised due to the composition process, where the agents have to be parallel composed into an agent capturing all possible behaviors of the multi-agent system prior to the verification phase. The second problem concerns the expressiveness of verification tools when modeling and verifying certain behaviors. Therefore, this paper tackles these problems by showing how multi-agent systems, specified as hybrid automata, can be modeled and verified using constraint logic programming(CLP). In particular, a CLP framework is presented to show how the composition of multi-agent behaviors can be captured dynamically during the verification phase. This can relieve the state space complexity that may occur as a result of the composition process. Additionally, the expressiveness of the CLP model flexibly allows not only to model multi-agent systems, but also to check various properties by means of the reachability analysis. Experiments are promising to show the feasibility of our approach.
Specifying behaviors of multi-agent systems (MASs) is a demanding task, especially when applied in safety-critical systems. In the latter systems, the specification of behaviors has to be carried out carefully in order to avoid side effects that might cause unwanted or even disastrous behaviors. Thus, formal methods based on mathematical models of the system under design are helpful. They not only allow us to formally specify the system at different levels of abstraction, but also to verify the consistency of the specified systems before implementing them. The formal specification aims a precise and unambiguous description of the behavior of MASs, whereas the verification aims at proving the satisfaction of specified requirements. A behavior of an agent can be described as discrete changes of its states with respect to external or internal actions. Whenever an action occurs, the agent moves from one state to another one. Therefore, an efficient way to model this type of discrete behaviors is to use a kind of state transition diagrams such as finite automata. One remarkable advantage of such transition diagrams is that they lend themselves formal analysis techniques using model checking. The latter is an automatic verification technique which determines whether given properties are satisfied within a model underlying a particular system. In realistic physical environments, however, it is necessary to consider continuous behaviors in addition to discrete behaviors of MASs. Examples of those type of behaviors include the movement of a soccer agent to kick off or to go to the ball, the process of putting out the fire by a fire brigade agent in a rescue scenario, or any other behaviors that depend on any timed physical law. The traditional state transition diagrams are not sufficient to combine these types of behaviors. Hybrid automata offer an elegant method to capture such types of behaviors. Hybrid automata extend regular state transition diagrams with methods that deal with those continuous actions such that the state transition diagrams are used to model the discrete changes of behaviors, while differential equations are used to model the continuous changes. The semantics of hybrid automata make them accessible to formal verification by means of model checking. The main goal of this thesis is to approach hybrid automata for specifying and verifying behaviors of MASs. However, specifying and and verifying behaviors of MASs by means of hybrid automata raises several issues that should be considered. These issues include the complexity, modularity, and the expressiveness of MASs' models. This thesis addresses these issues and provides possible solutions to tackle them.
RMTI (RIP with Metric based Topology Investigation) wurde in der AG Rechnernetze an der Universität Koblenz-Landau entwickelt. RMTI stellt eine Erweiterung zum RIP (Routing Information Protocol) dar, die das Konvergenzverhalten bei Netzwerkveränderungen, insb. bei Routingschleifen, verbessern soll. Dies geschieht durch Erkennen von Routingschleifen und Reduzieren des Count-to-infinity Problems. Um dieses gewünschte Verhalten nachweisen zu können, bedarf eine reichhaltige Evaluierung des RMTI- Algorithmus. Hierzu wurde in der gleichen Arbeitsgruppe die Client-/Server-Applikation XTPeer entwickelt. In Kombination mit anderen Software wie VNUML und Quagga Routing Suite lässt sich per XT-Peer der Algorithmus evaluieren. Die Applikation XTPeer generiert durch die Simulationen Daten. Diese können in Form von XML konforme SDF-Dateien exportiert werden. Diese können ohne weitere Auswertungen wieder in die XTPeer Applikation importiert werden. Die Evaluierung der Simulationen findet automatisiert nur an der aktuellen Simulation statt. Evaluierung über mehrere Simulationen muss der Benutzer manuell berechnen. Um diese Evaluierungsarbeiten für den Benutzer zu vereinfachen, verfolgt die vorliegende Diplomarbeit daher das Ziel, die XTPeer Applikation mit einem Auswertungsmodul zu erweitern. Die Auswertungen soll sich über alle gespeicherten Simulationsdaten und nicht wie bisher nur über die aktuell laufende Simulation erstrecken. Dies ermöglicht bessere statistisch verwertbare Aussagen. Zusätzlich können diese Auswertungsergebnisse grafisch unterstrichen werden.
Dieses Dokument schlägt ein Konzept für eine Personal Key Infrastruktur in iCity vor. Über ein Trust Center (TC) ausgestellte Zertiffkate gewährleisten einen sicheren Schlüsselaustausch mit nachweisbarer Authentisierung des Kommunikationspartners, Abhörsicherheit sowie Unverf älschtheit und Nachweisbarkeit der Nachrichten. Das gemeinsam vertrauensw ürdige TC muss während der Kommunikation nicht erreichbar sein. Es erhält lediglich öffentliche Informationen. Das Konzept stellt mehrere Sicherheitsstufen vor, die sichere Identiffkation und Anonymität unterschiedlich gewichten.
Conventional security infrastructures in the Internet cannot be directly adopted to ambient systems, especially if based on short-range communication channels: Personal, mobile devices are used and the participants are present during communication, so privacy protection is a crucial issue. As ambient systems cannot rely on an uninterrupted connection to a Trust Center, certiffed data has to be veriffed locally. Security techniques have to be adjusted to the special environment. This paper introduces a public key infrastructure (PKI) to provide secure communication channels with respect to privacy, confidentiality, data integrity, non-repudiability, and user or device authentication. It supports three certiffcate levels with a different balance between authenticity and anonymity. This PKI is currently under implementation as part of the iCity project.