Flexible coordination techniques for dynamic cloud service collaboration

The provision of individual, but also composed services is central in cloud service provisioning. We describe a framework for the coordination of cloud services, based on a tuple‐space architecture which uses an ontology to describe the services. Current techniques for service collaboration offer limited scope for flexibility. They are based on statically describing and compositing services. With the open nature of the web and cloud services, the need for a more flexible, dynamic approach to service coordination becomes evident. In order to support open communities of service providers, there should be the option for these providers to offer and withdraw their services to/from the community. For this to be realised, there needs to be a degree of self‐organisation. Our techniques for coordination and service matching aim to achieve this through matching goal‐oriented service requests with providers that advertise their offerings dynamically. Scalability of the solution is a particular concern that will be evaluated in detail

A flexible model for Web service discovery

Also published online by CEUR Workshop Proceedings (CEUR-WS.org, ISSN 1613-0073) Proceedings of the 1st International Workshop on Semantic Matchmaking and Resource Retrieval, SMR 06The advent of the SOA paradigm is expected to cause an increase in the number of available Web services. In this setting, advanced facilities for the discovery of Web services that provide a given functionality are required so that this increase does not create a bottleneck for the exploitation of services in an SOA. In this paper, we present a model for the discovery of Web services which relies on alternative views of Web service functional capabilities, allowing for different trade-offs between the accuracy of discovery results and the efficiency of the discovery process. Up to three filtering steps, with increasing complexity, can be successively applied in order to refine discovery results. Furthermore, the use of taxonomies of functional categories, close to the intuition of average users, is introduced by our model with a two-fold purpose: a) supporting the user in the description of goals and Web services, and b) allowing for a coarse-grained but highly efficient discovery. Due to its flexibility, the model proposed is expected to cover a wide range of use cases

Formal Firewall Conformance Testing: An Application of Test and Proof Techniques

Firewalls are an important means to secure critical ICT infrastructures. As configurable off-the-shelf prod\-ucts, the effectiveness of a firewall crucially depends on both the correctness of the implementation itself as well as the correct configuration. While testing the implementation can be done once by the manufacturer, the configuration needs to be tested for each application individually. This is particularly challenging as the configuration, implementing a firewall policy, is inherently complex, hard to understand, administrated by different stakeholders and thus difficult to validate. This paper presents a formal model of both stateless and stateful firewalls (packet filters), including NAT, to which a specification-based conformance test case gen\-eration approach is applied. Furthermore, a verified optimisation technique for this approach is presented: starting from a formal model for stateless firewalls, a collection of semantics-preserving policy transformation rules and an algorithm that optimizes the specification with respect of the number of test cases required for path coverage of the model are derived. We extend an existing approach that integrates verification and testing, that is, tests and proofs to support conformance testing of network policies. The presented approach is supported by a test framework that allows to test actual firewalls using the test cases generated on the basis of the formal model. Finally, a report on several larger case studies is presented

Supporting Task Constraints and Dependencies in Knowledge-intensive Processes

Knowledge-intensive processes are widely found in modern societies and important to many fields of work. Driven by knowledge gained only during their execution, this type of process brings along challenges like a gradually emerging structure, uncertainty and frequent changes. Through contribution and communication the knowledge workers involved in the process shape and improve it while advancing towards a common goal. One very important part of the knowledge are the dependencies that naturally exist between the tasks on which these workers perform. With the latter often being spatially divided, expressing the dependencies existing for their jobs is a determining factor for success. Relying on insufficient software systems or, even worse, on paperbased solutions for coordination proves to be error-prone and lacks reliance in practical scenarios. Adequate aid in form of information systems, specifically designed for knowledge-intensive processes and their accompanying challenges, and operated on by the knowledge workers themselves, is needed. The work on such systems is a still ongoing endeavor and in need of concepts and solutions. This work presents a concept for the support of constraints to express task dependencies in knowledge-intensive processes. With the focus on the unique challenges coming with the latter, the concept puts great emphasis on providing guidance instead of strict ruling, adaptability to frequent changes and usability in practical scenarios. A rule-based, declarative approach is laid out for applying the concept, designed to be ready for extension, to various systems alongside other, already existing functionality. Based on it, a catalog of constraints is given, with clear semantic meanings and effects, tailored towards the use in knowledge-intensive processes. A proof-of-concept prototype for it was implemented for the process-aware Support for Collaborative Knowledge Workers (proCollab) system, an example of an adequate and sophisticated solution

An Approach to Domain-Specific Reuse in Service-Oriented Environments

Domain engineering is successful in promoting reuse. An approach to domain-specific reuse in service-oriented environments is proposed to facilitate service requesters to reuse Web services. In the approach, we present a conceptual model of domain-specific services (called domain service). Domain services in a certain business domain are modeled by semantic and feature modeling techniques, and bound to Web services with diverse capabilities through a variability-supported matching mechanism. By reusing pre-modeled domain services, service requesters can describe their requests easily through a service customization mechanism. Web service selection based on customized results can also be optimized by reusing the pre-matching results between domain services and Web services. Feasibility of the whole approach is demonstrated on an example

A Framework for Collaborative Content Mashup with Pervasive Services

Kombineerides erinevaid teenuseid saavad mobiiltelefonid rahuldada paljusid tööstus ja ärivajadusi.Samas tuleb teenuste kombineerimise raames sisu õigesti tuvastamiseks ja tõlgendamiseks avastada ja töödelda suurt hulka andmeid. Kuna ainult ühe seadme kasu-tamine mingi ülesande lahendamiseks ei ole väga efektiivne on ühiste eesmärkide saa-vutamiseks soovitatav tööd mitme seadme vahel jagada. Pakume välja ja arendame üldraamistikku, mis toetab teenustele orienteeritud sisu segunemist ning laialt levinud teenuste loomise integreerimist, mis toimuks Business Process Execution Language (BPEL)-tuginevale kollaboratsioonile. Esitasime kollaboratsioonis seadmetele ressursi-säästliku teisaldamise plaani ja implementeerimise selle proof of concept'ina (kontseptsiooni tõestus). Hinnangu tulemused näitavad, et raamistik toetab kollaboratiivset ülesannete teisaldamise kava, mis vähendab mobiilsete seadete ressursside kasutamist.By composing pervasive services, mobile phones can support various industrial and commercial needs. However, the pervasive services composition involves discovering and processing a large amount of data in order to identify and interpret the content. Due to the limitation of the single device capability, it is advisable to collaborate with other devices via a wireless network to accomplish common goals. In this thesis, we propose and develop a generic framework that supports service-oriented content mashup and integrating pervasive services composition in the Business Process Execution Language (BPEL)-based collaboration. A resource-aware offloading scheme to collaborative devices has been proposed and implemented as a proof of concept. The evaluation results have shown that the framework supports collaborative task-offloading scheme that reduces the resource usage of mobile devices

Semantic search and composition in unstructured peer-to-peer networks

This dissertation focuses on several research questions in the area of semantic search and composition in unstructured peer-to-peer (P2P) networks. Going beyond the state of the art, the proposed semantic-based search strategy S2P2P offers a novel path-suggestion based query routing mechanism, providing a reasonable tradeoff between search performance and network traffic overhead. In addition, the first semantic-based data replication scheme DSDR is proposed. It enables peers to use semantic information to select replica numbers and target peers to address predicted future demands. With DSDR, k-random search can achieve better precision and recall than it can with a near-optimal non-semantic replication strategy. Further, this thesis introduces a functional automatic semantic service composition method, SPSC. Distinctively, it enables peers to jointly compose complex workflows with high cumulative recall but low network traffic overhead, using heuristic-based bidirectional haining and service memorization mechanisms. Its query branching method helps to handle dead-ends in a pruned search space. SPSC is proved to be sound and a lower bound of is completeness is given. Finally, this thesis presents iRep3D for semantic-index based 3D scene selection in P2P search. Its efficient retrieval scales to answer hybrid queries involving conceptual, functional and geometric aspects. iRep3D outperforms previous representative efforts in terms of search precision and efficiency.Diese Dissertation bearbeitet Forschungsfragen zur semantischen Suche und Komposition in unstrukturierten Peer-to-Peer Netzen(P2P). Die semantische Suchstrategie S2P2P verwendet eine neuartige Methode zur Anfrageweiterleitung basierend auf Pfadvorschlägen, welche den Stand der Wissenschaft übertrifft. Sie bietet angemessene Balance zwischen Suchleistung und Kommunikationsbelastung im Netzwerk. Außerdem wird das erste semantische System zur Datenreplikation genannt DSDR vorgestellt, welche semantische Informationen berücksichtigt vorhergesagten zukünftigen Bedarf optimal im P2P zu decken. Hierdurch erzielt k-random-Suche bessere Präzision und Ausbeute als mit nahezu optimaler nicht-semantischer Replikation. SPSC, ein automatisches Verfahren zur funktional korrekten Komposition semantischer Dienste, ermöglicht es Peers, gemeinsam komplexe Ablaufpläne zu komponieren. Mechanismen zur heuristischen bidirektionalen Verkettung und Rückstellung von Diensten ermöglichen hohe Ausbeute bei geringer Belastung des Netzes. Eine Methode zur Anfrageverzweigung vermeidet das Feststecken in Sackgassen im beschnittenen Suchraum. Beweise zur Korrektheit und unteren Schranke der Vollständigkeit von SPSC sind gegeben. iRep3D ist ein neuer semantischer Selektionsmechanismus für 3D-Modelle in P2P. iRep3D beantwortet effizient hybride Anfragen unter Berücksichtigung konzeptioneller, funktionaler und geometrischer Aspekte. Der Ansatz übertrifft vorherige Arbeiten bezüglich Präzision und Effizienz

CloudOps: Towards the Operationalization of the Cloud Continuum: Concepts, Challenges and a Reference Framework

The current trend of developing highly distributed, context aware, heterogeneous computing intense and data-sensitive applications is changing the boundaries of cloud computing. Encouraged by the growing IoT paradigm and with flexible edge devices available, an ecosystem of a combination of resources, ranging from high density compute and storage to very lightweight embedded computers running on batteries or solar power, is available for DevOps teams from what is known as the Cloud Continuum. In this dynamic context, manageability is key, as well as controlled operations and resources monitoring for handling anomalies. Unfortunately, the operation and management of such heterogeneous computing environments (including edge, cloud and network services) is complex and operators face challenges such as the continuous optimization and autonomous (re-)deployment of context-aware stateless and stateful applications where, however, they must ensure service continuity while anticipating potential failures in the underlying infrastructure. In this paper, we propose a novel CloudOps workflow (extending the traditional DevOps pipeline), proposing techniques and methods for applications’ operators to fully embrace the possibilities of the Cloud Continuum. Our approach will support DevOps teams in the operationalization of the Cloud Continuum. Secondly, we provide an extensive explanation of the scope, possibilities and future of the CloudOps.This research was funded by the European project PIACERE (Horizon 2020 Research and Innovation Programme, under grant agreement No. 101000162)