Flexible workflows to support transactional service composition in mobile environments

Service oriented computing provides suitable means to technically support distributed collaboration of heterogeneous devices, for example those present in mobile environments. E.g., many applications are built on composite Web- Services. However, when executing these applications in dynamic environments, failures of participating entities have to be optimistically coped with, in order to avoid inconsistent system states and thereby provide suitable correctness guarantees. Transactional coordination for services so far lacks the possibility to adapt failure handling to the current execution context, e.g. dynamically bound services at runtime. In this paper, we employ transactional service properties to ensure reliable, i.e., correct execution of workflows by still respecting the autonomy of participants. We propose algorithms to verifiy and alter the structure of the composition at runtime, thus adapting the control flow to the current execution context to ensure correct execution

An architecture for certification-aware service discovery

Service-orientation is an emerging paradigm for building complex systems based on loosely coupled components, deployed and consumed over the network. Despite the original intent of the paradigm, its current instantiations are limited to a single trust domain (e.g., a single organization). Also, some of the key promises of service-orientation - such as the dynamic orchestration of externally provided software services, using runtime service discovery and deployment - are still unachieved. One of the main reasons for this is the trust gap that normally arises when software services, offered by previously unknown providers, are to be selected at run-time, without any human intervention. To close this gap, the concept of machine-readable security certificates (called asserts) has been recently introduced, which paves the way to automated processing about security properties of services. Similarly to current security certification schemes, the assessment of the security properties of a service is delegated to an independent third party (certification authority), who issues a corresponding assert, bound to the service. In this paper, we propose an architecture, which exploits the assert concept to realise a certification-aware service discovery framework. The architecture supports the discovery of single services based on certified security properties (in additional to the usual functional properties), as well as the dynamic synthesis of service compositions, that satisfy the given security properties. The architecture is extensible, thus allowing for a range of domain specific matchmaking components, to cover dimensions related to, e.g., performance, cost and other non-functional characteristics

Reliable Fault Tolerance System for Service Composition in Mobile Ad Hoc Network

A Due to the rapid development of smart processing mobile devices, Mobile applications are exploring the use of web services in MANETs to satisfy the user needs. Complex user needs are satisfied by the service composition where a complex service is created by combining one or more atomic services. Service composition has a significant challenge in MANETs due to its limited bandwidth, constrained energy sources, dynamic node movement and often suffers from node failures. These constraints increase the failure rate of service composition. To overcome these, we propose Reliable Fault Tolerant System for Service Composition in MANETs (RFTSC) which makes use of the checkpointing technique for service composition in MANETs. We propose fault policies for each fault in service composition when the faults occur. Failure of services in the service composition process is recovered locally by making use of Checkpointing system and by using discovered services which satisfies the QoS constraints. A Multi-Service Tree (MST) is proposed to recover failed services with O(1) time complexity. Simulation result shows that the proposed approach is efficient when compared to existing approaches

Sensor Data Visualization in Virtual Globe

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.With the recent developments related with sensors in matters of standardization and accessibility, valuable data covering different geographical subjects have become widely available. The applications that can leverage sensor data are still under development and there is much to do in this subject in the scientific community. Data visualization tools are one of the immediately relevant needs related with sensor data. Such tools would help to increase the understanding and exploration of the data from which many other fields can get benefits. Virtual Globes are becoming increasingly popular in the society. The existence of several implementations and millions of users (scientific and no scientific) around the world are a proof of their increasing usability as a tool for representing and sharing geographical content. In this document we present a generic tool for visualizing sensor data retrieved from SOS servers over the NASA World Wind virtual globe. For this, we started by creating a classification of sensor data that helps in defining possible visualizations for the different types of sensor data. Using this classification as a basis, we have implemented a set of visualization types to ease sensor data exploration. We also included analysis capabilities by integrating the SEXTANTE library in the visualization tool. The results of the analysis can be included in the virtual globe as part of the visualizations

Integrating Mobile Tasks with Business Processes: A Self-Healing Approach

Process management technology constitutes a fundamental component of any service-driven computing environment. Process management facilitates both the composition of services at design time and their orchestration at run time. In particular, when applying the service paradigm to enterprise integration management, high flexibility is required. In this context, atomic as well as composite services representing the business functions should be quickly adaptable to cope with dynamic business changes. Furthermore, they should enable mobile and quick access to enterprise information. The growing maturity of smart mobile devices has fostered their prevalence in knowledge-intensive areas in the enterprise as well. As a consequence, process management technology needs to be enhanced with mobile task support. However, tasks hitherto executed stationarily, cannot be simply transferred in order to run on smart mobile devices. Many research groups focus on the partitioning of processes and the distributed execution of the resulting fragments on smart mobile devices. Opposed to this fragmentation concept, this chapter proposes an approach to enable the robust and flexible execution of single process tasks on smart mobile devices by provisioning self-healing techniques to address the smooth integration of mobile tasks with business processes

Context-Based Handling of Mobile Process Activities

Process technology constitutes a crucial component of information systems. In this context, high flexibility is required as business functions must be quickly adaptable to cope with dynamic business changes. As recent developments allow for the use of mobile devices in knowledge-intensive areas, it is often demanded to enhance process-aware information systems with mobile activity support. In general, the technical integration of this activity type with existing process management technology is challenging. For example, protocols governing the communication between mobile devices and process management systems must be adapted. If a mobile context shall be additionally considered, the integration gets even more complex. However, the use of a mobile context offers advantages. For example, the mobile activity execution time may be decreased if mobile activities are only assigned to those users whose location is beneficial. This chapter proposes an approach to enable the robust handling of single process activities on mobile devices based on a mobile process model