Lukasz Juszczyk

Script-Based Generation of Dynamic Testbeds for SOA

This paper addresses one of the major problems of SOA software development: the lack of support for testing complex service-oriented systems. The research community has developed various means for checking individual Web services but has not come up with satisfactory solutions for testing systems that operate in service-based environments and, therefore, need realistic testbeds for evaluating their quality. We regard this as an unnecessary burden for SOA engineers. As a proposed solution for this issue, we present the Genesis2 testbed generator framework. Genesis2 supports engineers in modeling testbeds and programming their behavior. Out of these models it generates running instances of Web services, clients, registries, and other entities in order to emulate realistic SOA environments. By generating real testbeds, our approach assists engineers in performing runtime tests of their systems and particular focus has been put on the framework’s extensibility to allow the emulation of arbitrarily complex environments. Furthermore, by exploiting the advantages of the Groovy language, Genesis2 provides an intuitive yet powerful scripting interface for testbed control.

Dynamic replication and synchronization of web services for high availability in mobile ad-hoc networks

Web services are gaining high popularity and importance on mobile devices. Connected to ad-hoc networks, they provide the possibility to establish spontaneously even complex service-based workflows and architectures. However, usually these architectures are only as stable and reliable as the underlying network infrastructure. Since topologies of mobile ad-hoc networks behave unpredictably, dependability within them can be only achieved with a dynamic replication mechanism. In this paper we present a highly flexible solution for replication and synchronization of stateful Web services and discuss the behavior of the implemented prototype in large-scale simulations.

ESCAPE: an adaptive framework for managing and providing context information in emergency situations

Supporting adaptive processes in tackling emergency situations, such as disasters, is a key issue for any emergency management system. In such situations, various teams are deployed in many sites, at the front-end or back-end of the situations, to conduct tasks handling the emergency. Context information is of paramount importance in assisting the adaptation of these tasks. However, there is a lack of middleware supporting the management of context information in emergency situations. This paper presents a novel framework that manages and provides various types of context information required for adapting processes in emergency management systems.

Web service discovery, replication, and synchronization in ad-hoc networks

Mobile ad-hoc networks with their arbitrary topologies are a difficult domain for providing highly available Web services. Since hosts can move unpredictably, finding services and featuring their constant and reliable functionality poses a challenge. In this paper we present a flexible system which is not only bound to ad-hoc networks, but can be used in any other environment. Our solution offers a discovery technique which keeps UDDI information in distributed registries up-to-date and includes a replication and synchronization mechanism which provides backup services for a highly increased service dependability.

Runtime Behavior Monitoring and Self-Adaptation in Service-Oriented Systems

Mixed service-oriented systems composed of human actors and software services build up complex interaction networks. Without any coordination, such systems may exhibit undesirable properties due to unexpected behavior. Also, communications and interactions in such networks are not preplanned by top-down composition models. Consequently, the management of service-oriented applications is difficult due to changing interaction and behavior patterns that possibly contradict and result in faults from varying conditions and misbehavior in the network. In this paper we present a self-adaptation approach that regulates local interactions to maintain desired system functionality. To prevent degraded or stalled systems, adaptations operate by link modification or substitution of actors based on similarity and trust metrics. Unlike a security perspective on trust, we focus on the notion of socially inspired trust. We design an architecture based on two separate independent frameworks. One providing a real Web service test bed extensible for dynamic adaptation actions. The other is our self-adaptation framework including all modules required by systems with self-* properties. In our experiments we study a trust and similarity based adaptation approach by simulating dynamic interactions in the real Web services test bed.

GENESIS - A Framework for Automatic Generation and Steering of Testbeds of ComplexWeb Services

Nowadays, the importance of Web services is steadily increasing in domains where interoperability is of paramount importance. This trend is especially observable in complex computer systems which consist of a large number of interacting distributed components, often implemented using Web services. Large-scale systems and high complexity usually result in higher error-proneness in the development process. This should be addressed as early as possible during the development of complex service-oriented systems, ideally before they are actually deployed on a distributed infrastructure. In this paper we present GENESIS - a software framework for solving this problem. Our framework allows automatic generation and steering of testbeds of complex Web services, thereby empowering developers to specify functional and non-functional properties of Web services, to generate and deploy Web service instances on remote hosting environments, to enhance the functionality of the framework with plug-ins, and to control the behavior of the testbed during runtime.

A middleware for service-oriented communication in mobile disaster response environments

Today, the work of disaster response teams is being increasingly supported and coordinated by using portable computing devices. Connected to mobile ad-hoc networks, these devices establish a communication infrastructure immune to damages caused by natural disasters. However, ad-hoc networks are dynamic and volatile environments, which hampers hosting of critical applications relying on fast responsiveness. These difficulties can be mitigated to some extent at the middleware level. In this paper we present RESCUE, an open-source middleware for service-oriented communication in mobile disaster response environments. RESCUE has been designed to address challenges of dynamic ad-hoc networks for service discovery and invocation and provides an infrastructure for flexible mobile systems based on loosely coupled services.

Adaptive Query Routing on Distributed Context - The COSINE Framework

Context-awareness has become a desired key feature of todays mobile systems, yet, its realization still remains a challenge. On the one hand, mobile computing provides great potential for adaptations based on sensed contextual information. On the other hand, the lack of dependability in mobile networks hampers an efficient provision of this information to requesting clients. In this paper we present COSINE, a context management framework for mobile environments. COSINE has been developed on the principles of peer-to-peer computing and establishes context sharing infrastructures consisting of loosely coupled Web services. The services represent modular entities of the applied context model and manage the retrieval, aggregation, query, and provision of context data. Clients access the distributed information transparently via proxies and a self-adaptive routing of queries provides increased fault-tolerance, which is essential in mobile environments.

Programmable Fault Injection Testbeds for Complex SOA

The modularity of Service-oriented Architectures (SOA) allows to establish complex distributed systems comprising e.g., services, clients, brokers, and workflow engines. A growing complexity, however, automatically increases the number of potential fault sources which have effects on the whole SOA. Fault handling mechanisms must be applied in order to achieve a certain level of robustness. In this paper we do not deal with fault-tolerance itself but regard the problem from a different perspective: how can fault-tolerance be evaluated? We argue that this can be best done by testing the system at runtime and observing its reaction on occuring faults. Though, engineers are facing the problem of how to perform such tests in a realistic manner in order to get meaningful results. As our contribution to this issue we present an approach for generating fault injection testbeds for SOA. Our framework allows to model testbeds and program their behavior, to generate running instances out of it, and to inject diverse types of faults. The strength of our approach lies in the customizability of the testbeds and the ability to program the fault-injecting mechanisms in a convenient manner.

Vimoware - A Toolkit for Mobile Web Services and Collaborative Computing

Mobile devices are considered to be very useful in ad-hoc and team collaborations, for example in disaster responses, where dedicated infrastructures are not available. Such collaborations normally require flexible and interoperable services while running on mobile devices and being integrated with various other services. Therefore, middleware and toolkits for developing mobile services which can be accessed by using standard interfaces and protocols are in demand. Due to the lack of tools, the support of the development of Web services and collaboration tools on mobile devices is still limited. This paper presents the Vimoware toolkit which allows both developers and users to develop Web services for mobile devices, to conduct ad-hoc team collaborations by executing pre-defined or on-situ flows of tasks, and to test collaboration scenarios.