Catálogo de publicaciones - libros

Event logging and log files are playing an important role in system and network security. Log files record computer system activities, are used to provide requirements of reliability, security and accountability applications. Information stored in log files can be obtained from different devices, not necessarily clock synchronized, and they do not arrive in the same order they are generated. Nevertheless, log information has to be coherent in time to be useful. To support the events we propose to use Lamport’s logic clocks, originated at different sources, in a causal relationship. As a result the administrator will count all the events involved general idea in a computer incident. A model implementation is also presented.

The cost of developing and deploying web applications is reduced by dynamically integrating other heterogeneous self-contained web services. However, the malfunctioning of such systems would cause severe losses. This paper presents a technique for building reliable web applications composed of web services. All relevant web services are linked to the component under test at the testing time; thus, the availability of suitable web services is guaranteed at invocation time. In our technique, a web application and its composed components are specified by a two-level abstract model. The web application is represented as and the behavior of the composed components is represented as a . Three sets of test sequences are generated from the WSDL files, the TLTS and the TPG representing the integrated components and the whole web application. Test cases are executed automatically using a test execution algorithm and a test framework is also presented. This framework wraps the test cases with SOAP interfaces and validates the testing results obtained from the web services.

The long latency related with Mobile IPv6’s home-address and care-of-address tests can considerably impact delay-sensitive applications. Applying the in a proper way over the networks can prevent the source IP address spoofing which is used by the malicious nodes to launch some sort of attacks. We have suggested a new communication mode which is called Very Early Binding Update Mode (VEBU) for mobility in IPv6. The VEBU eliminates the long delay-latency associated with mobile IPv6 mobility messages either in start of a session or during a session after a handover. Our communication mode allows an optimistic mobile node (MN) to run in one less round-trip-time compared to the route optimization mode.

In this paper we describe an assume/guarantee based execution constraints synthesis algorithm for concurrent threads executing on parallel platforms. Threads are loops which can have several control points, such as the activation of loop iterations and the interaction with other threads. Real-time applications such as multimedia applications are usually specified using this kind of concurrent interacting threads. The proposed compositional algorithm outputs a set of sufficient constraints on the control points in order to meet timing objectives. The paper first presents the timed system model we use to specify such applications. Then, the constraints synthesis algorithm is presented and illustrated on a real-time video application.

The wireless resources such as bandwidth in case of wireless networks (WNs) are very restricted compared with wired networks. Thus, providing integrated service for WNs could lead to high traffic and instable performance because of the high link error. However, some application signaling protocols transport information about their resource requirements; this information is similar to that transported by QoS-signaling protocol. The usage of these application signaling protocols to perform a kind of QoS can reduce the control traffic generated on the wireless side effectively. In this respect, new structure of QoS is presented, where a wireless access server (WAS) communicates with the applications server, and the base stations in order to provide a kind of QoS. This method is applied on SIP-based WLAN telephony. The experiments on our implemented software presented relatively small delay times, in average: 13 ms for flow reservation and 16 ms for updating the wireless state in WAS. This provides an effective structure of QoS for VoIP applications.

This chapter presents architecture to design emotional agents evolving in an artificial 3D environment. The agent behavior and environment emulator are independent of implementation. To achieve this, a Language of Interface for Animations in 3D called LIA-3D, is presented. The agent and environment simulator uses LIA to establish communication with each other.

We present a new algorithm that solves the problem of distributively determining the maximum flow in an asynchronous network. This distributed algorithm is based on the preflow-push technique. Sequential processes, executing the same code over local data, exchange messages with neighbors to establish the max flow. This algorithm is derived to the case of multiple sources and/or sinks without modifications. For a network of nodes and arcs, the algorithm achieves message complexity and time complexity.