8778784
Constraint-based negotiation in a multi-agent information system with multiple platform support
Agent technologies have been deployed to model and implement e-commerce activities as multi-agent information systems (MAIS). Agents provide services to one another for mutual gain on behalf of their users. This paper presents an MAIS infrastructure based on belief-desire-in tension (BDI) agent architecture, constraint technology, and contemporary Web services to facilitate negotiation support. Further, the MAIS infrastructure also supports customizable degree of agent delegation for users on different platforms, with or without agent support. We present a constraint-based negotiation protocol extended for a MAIS environment and detail the required adaptations on different platforms from a three-tier implementation architecture aspect.
16980226
Contextual local analysis in the design of distributed systems
Compositional Reachability Analysis is a popular technique for studying behaviour of finite-state distributed systems. The technique is applied by a repetition oflocal analyses, the basic steps of which are to construct and examine the behaviour of subsystems. In most cases, behaviour of the subsystem is constrained by its environment (calledcontext) formed by neighbouring components. These behaviour constraints are normally not considered when using local analysis in conventional techniques of compositional reachability analysis. As a result, many execution paths derived in the local analysis may not be actually traversed by the subsystem. These paths are made impossible to traverse by the constraints. The paths are unnecessary for understanding the subsystem behaviour and their removal greatly simplifies the local analysis. In this paper, we describe an elegant technique, calledcontextual local analysis, to include these behaviour constraints in conventional local analysis. The technique can alleviate dramatically the state explosion problem encountered in local analysis. It also facilitates early detection of anomalous behaviour of a distributed system at its design stage. The technique works by composing an interface process with the subsystem being examined. That interface process is so chosen that it captures behaviour constraints enforced by the environment while its composition with the subsystem does not affect the global system behaviour. This interface process can be automatically derived using a simple algorithm. The contextual local analysis technique results in a simplified labelled transition system which can be used as a substitute for the original subsystem in the construction of the global system behaviour. The contextual local analysis technique is illustrated with a clients/server example implementing a round-robin protocol.
1370408
A three-layer architecture for e-contract enforcement in an e-service environment
In an e-service environment, contracts are important for attaining business process interoperability and enforcing their proper enactment. An e-contract is the computerized facilitation or automation of a contract in a cross-organizational business process. We find that e-contract enforcement can be divided into multiple layers and perspectives, which has not been adequately addressed in the literature. This problem is challenging as it involves monitoring the enactment of business processes in counter parties outside an organization's boundary. This paper presents an architecture for e-contract enforcement with three layers, viz., document layer, business layer, and implementation layer. In the document layer, contracts are composed of different types of clauses. In the business layer, e-contract enforcement activities are defined through the realization of contract clauses as business rules in event-condition-action (ECA) form. In the implementation layer, cross-organizational e-contract enforcement interfaces are implemented with contemporary Enterprise Java Bean and Web services. We present a methodology for the engineering of e-contracts enforcement from a high-level document-view down to the implementation layer based on this architecture, using a supply-chain example. As a result, e-contracts can be seamlessly defined and enforced. Conceptual models of various layers are given in the Unified Modeling Language (UML).
1708697
Enhancing compositional reachability analysis with context constraints
Compositional techniques have been proposed for traditional reachability analysis in order to introduce modularity and to control the state explosion problem. While modularity has been achived, state explosion is still a problem. Indeed, this problem may even be exacerbated as a locally minimised subsystem may contain many states and transitions forbidden by its context or environments. This paper presents a method to alleviate this problem effectively by including context constraints in local subsystem minimisation. The global behaviour generated using the method is observationally equivalent to that generated by compositional reachability analysis without the inclusion of context constraints.Context constraints, specified as interface processes, are restrictions imposed by the environment on subsystem behaviour. The minimisation produces a simplified machine that describes the behaviour of the subsystem constrained by its context. This machine can also be used as a substitute for the original subsystem in the subsequent steps of the compositional reachability analysis. Interface processes capturing context constraints can be specified by users or automatically constructd using a simple algorithm. The concepts in the paper are illustrated with a clients/server system.
8159009
A Three-Layer Framework for Cross-Organizational e-Contract Enactment
In an e-commerce environment, contracts are important for attaining business process interoperability and enforcing their proper enactment. An e-contract is the computerized facilitation or automation of a contract in a cross-organizational business process. We find that e-contract facilitation can be divided into multiple levels and perspectives, which has not been adequately addressed before. In this paper, we present a framework for e-contract enactment with three layers, viz., business layer, structural layer, and implementation layer. In the business layer, e-contracts are defined through analyzing the contract clauses to business rules and business entities. In the structural layer, requirements for the E-contract enactment workflow are elucidated through requirement analysis to cover both static and dynamic aspects. In the implementation layer, workflows and cross-organizational interoperating interfaces are implemented using contemporary Enterprise Java Bean and Web services. In this paper, we present the methodology and process for engineering the functional aspects of e-contracts from high-level business-view down to implementation layer based on this framework, illustrated with an investment example. The framework allows an e-contract to be seamlessly defined and enacted. The framework is modeled in UML.
18545755
A Framework for Distributed Object-Oriented Testing
Distributed programming and object-oriented programming are two popular programming paradigms. The former is driven by advances in networking technology whereas the latter provides vigorous software principles needed in developing complex software systems. While more and more distributed object-oriented software has appeared, not much work exists on the testing of these systems in an integrated manner. Instead, the distributed and object features have been tested separately. In this paper, we propose an integrated framework known as DOOT for incremental testing of distributed object-oriented software systems. It combines various testing techniques to provide comprehensive test coverage at four levels — class testing, intra-cluster testing, inter-cluster testing and system testing. Each level uses a specific fault model, test strategy and test case generation that build on the previous test level to reduce the overall test effort. They are designed to handle the distinct requirements of the two paradigms at each level. Moreover, a reduction algorithm for testing the inherited class is also included in the framework. The approach is illustrated using a real life example of a conferencing system.
12589493
Automatic analysis of firewall and network intrusion detection system configurations
Given a network that deploys multiple firewalls and network intrusion detection systems (NIDSs), ensuring that these security components are correctly configured is a challenging problem. Although models have been developed to reason independently about the effectiveness of firewalls and NIDSs, there is no common framework to analyze their interaction. This paper presents an integrated, constraint-based approach for modeling and reasoning about these configurations. Our approach considers the dependencies among the two types of components, and can reason automatically about their combined behavior. We have developed a tool for the specification and verification of networks that include multiple firewalls and NIDSs, based on this approach. This tool can also be used to automatically generate NIDS configurations that are optimal relative to a given cost function.
34315877
Detecting Disruptive Routers in Wireless Sensor Networks
In wireless sensor networks, sensor nodes are typically resource constrained and used as routers to forward packets for other nodes. Compromised sensor nodes may be able to cause network-wide denial of service by dropping or corrupting packets. This paper presents a novel, lightweight approach for detecting disruptive routers that drop or corrupt packets.
15410506
Fast similarity search on video signatures
Video signatures are compact representations of video sequences designed for efficient similarity measurement. In this paper, we propose a feature extraction technique to support fast similarity search on large databases of video signatures. Our proposed technique transforms the high dimensional video signatures into low dimensional vectors where similarity search can be efficiently performed. We exploit both the upper and lower bounds of the triangle inequalities in approximating the high-dimensional metric, and combine this approximation with the classical PCA to achieve the target dimension. Experimental results on a large set of Web video sequences show that our technique outperforms fastmap, Haar wavelet, PCA, and triangle-inequality pruning.
6490713
An Architecture for an Adaptive Intrusion-Tolerant Server
We describe a general architecture for intrusion-tolerant enterprise systems and the implementation of an intrusion-tolerant Web server as a specific instance. The architecture comprises functionally redundant COTS servers running on diverse operating systems and platforms, hardened intrusion-tolerance proxies that mediate client requests and verify the behavior of servers and other proxies, and monitoring and alert management components based on the EMERALD intrusion-detection framework. Integrity and availability are maintained by dynamically adapting the system configuration in response to intrusions or other faults. The dynamic configuration specifies the servers assigned to each client request, the agreement protocol used to validate server replies, and the resources spent on monitoring and detection. Alerts trigger increasingly strict regimes to ensure continued service, with graceful degradation of performance, even if some servers or proxies are compromised or faulty. The system returns to less stringent regimes as threats diminish. Servers and proxies can be isolated, repaired, and reinserted without interrupting service.
30482723
Efficient video similarity measurement with video signature
The proliferation of video content on the Web makes similarity detection an indispensable tool in Web data management, searching, and navigation. We propose a number of algorithms to efficiently measure video similarity. We define video as a set of frames, which are represented as high dimensional vectors in a feature space. Our goal is to measure ideal video similarity (IVS), defined as the percentage of clusters of similar frames shared between two video sequences. Since IVS is too complex to be deployed in large database applications, we approximate it with Voronoi video similarity (VVS), defined as the volume of the intersection between Voronoi cells of similar clusters. We propose a class of randomized algorithms to estimate VVS by first summarizing each video with a small set of its sampled frames, called the video signature (ViSig), and then calculating the distances between corresponding frames from the two ViSigs. By generating samples with a probability distribution that describes the video statistics, and ranking them based upon their likelihood of making an error in the estimation, we show analytically that ViSig can provide an unbiased estimate of IVS. Experimental results on a large dataset of Web video and a set of MPEG-7 test sequences with artificially generated similar versions are provided to demonstrate the retrieval performance of our proposed techniques.