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

MADServer: An Architecture for Opportunistic Mobile Advanced Delivery

Rapid increases in cellular data traffic demand creative alternative delivery vectors for data. Despite the conceptual attractiveness of mobile data offloading, no concrete web server architectures integrate intelligent offloading in a production-ready and easily deployable manner without relying on vast infrastructural changes to carriers’ networks. Delay-tolerant networking technology offers the means to do just this. We introduce MADServer, a novel DTN-based architecture for mobile data offloading that splits web con- tent among multiple independent delivery vectors based on user and data context. It enables intelligent data offload- ing, caching, and querying solutions which can be incorporated in a manner that still satisfies user expectations for timely delivery. At the same time, it allows for users who have poor or expensive connections to the cellular network to leverage multi-hop opportunistic routing to send and receive data. We also present a preliminary implementation of MADServer and provide real-world performance evaluations

Ontology-based composition and matching for dynamic cloud service coordination

Recent cross-organisational software service offerings, such as cloud computing, create higher integration needs. In particular, services are combined through brokers and mediators, solutions to allow individual services to collaborate and their interaction to be coordinated are required. The need to address dynamic management - caused by cloud and on-demand environments - can be addressed through service coordination based on ontology-based composition and matching techniques. Our solution to composition and matching utilises a service coordination space that acts as a passive infrastructure for collaboration where users submit requests that are then selected and taken on by providers. We discuss the information models and the coordination principles of such a collaboration environment in terms of an ontology and its underlying description logics. We provide ontology-based solutions for structural composition of descriptions and matching between requested and provided services

A planning approach to the automated synthesis of template-based process models

The design-time specification of flexible processes can be time-consuming and error-prone, due to the high number of tasks involved and their context-dependent nature. Such processes frequently suffer from potential interference among their constituents, since resources are usually shared by the process participants and it is difficult to foresee all the potential tasks interactions in advance. Concurrent tasks may not be independent from each other (e.g., they could operate on the same data at the same time), resulting in incorrect outcomes. To tackle these issues, we propose an approach for the automated synthesis of a library of template-based process models that achieve goals in dynamic and partially specified environments. The approach is based on a declarative problem definition and partial-order planning algorithms for template generation. The resulting templates guarantee sound concurrency in the execution of their activities and are reusable in a variety of partially specified contextual environments. As running example, a disaster response scenario is given. The approach is backed by a formal model and has been tested in experiment

Game engines and MAS: tuplespace-based interaction in Unity3D

I Game Engines stanno acquisendo sempre più importanza sia in ambito industriale, dove permettono lo sviluppo di applicazioni moderne e videogiochi, sia in ambito di ricerca, in particolare nel contesto dei sistemi multi-agente (MAS). La loro capacità espressiva, unita al supporto di tecnologie e funzionalità innovative, permette la creazione di sistemi moderni e complessi in maniera più efficiente: il loro continuo avanzamento tecnologico li ha portati ad essere una realtà su cui fare affidamento nella produzione di vari applicativi diversi, come applicazioni di realtà aumentata/virtuale/mista, simulazioni immersive, costruzione di mondi virtuali e 3D, ecc. Ciononostante, soffrono la mancanza di proprie astrazioni e meccanismi che possano essere affidabili e utilizzati per aggredire la complessità durante il design di sistemi complessi. Il tentativo di sfruttare le caratteristiche della teoria dei MAS all'interno degli ambienti di sviluppo dei Game Engines procede secondo questa direzione: integrando le astrazioni costituenti i MAS all'interno dei Game Engines, con particolare riferimento ai modelli di coordinazione tra agenti, può portare a nuove soluzioni, riuscendo a risolvere problemi tecnologici grazie all'aiuto degli engine grafici. Questa tesi utilizza il Game Engine Unity3D proponendo due librerie C#, le quali sfruttano una precedente integrazione dello stesso framework con il Prolog per l'abilitazione di un modello di interazione e coordinazione basato su spazi di tuple, utilizzabile tramite l'implementazione di primitive LINDA. Le librerie offrono interfacce di programmazione (API) sfruttabili dai programmatori C# Unity3D per integrare nelle loro creazioni il supporto a tale modello, con una nuova modalità per la gestione della coordinazione tra oggetti in Unity3D e fornisce importanti proprietà, essendo fondamentale nel contesto dei MAS dal punto di vista dell'ingegnerizzazione di sistemi complessi e della gestione delle interazioni tra agenti

On component-oriented access control in lightweight virtualized server environments

2017 Fall.Includes bibliographical references.With the advancements in contemporary multi-core CPU architectures and increase in main memory capacity, it is now possible for a server operating system (OS), such as Linux, to handle a large number of concurrent services on a single server instance. Individual components of such services may run in different isolated runtime environments, such as chrooted jails or related forms of OS-level containers, and may need restricted access to system resources and the ability to share data and coordinate with each other in a regulated and secure manner. In this dissertation we describe our work on the access control framework for policy formulation, management, and enforcement that allows access to OS resources and also permits controlled data sharing and coordination for service components running in disjoint containerized environments within a single Linux OS server instance. The framework consists of two models and the policy formulation is based on the concept of policy classes for ease of administration and enforcement. The policy classes are managed and enforced through a Lightweight Policy Machine for Linux (LPM) that acts as the centralized reference monitor and provides a uniform interface for regulating access to system resources and requesting data and control objects. We present the details of our framework and also discuss the preliminary implementation and evaluation to demonstrate the feasibility of our approach

Automated Code Management for Service Oriented Computing in Ad Hoc Networks

Ad hoc networks are dynamic environments where fre-quent disconnections and transient interactions lead to de-coupled computing. Typically, participants in an ad hoc network are small mobile devices such as PDAs or cellu-lar phones that have a limited amount of resources avail-able locally, and must leverage the resources on other co-located devices to provide the user with a richer set of func-tionalities. Service-oriented computing (SOC), an emerging paradigm that seeks to establish a standard way of mak-ing resources and capabilities available for use by others in the form of services, is a useful model for engineering soft-ware that seeks to exploit capabilities on remote devices. This paper proposes an automatic code management sys-tem supporting SOC in ad hoc networks. The system is re-sponsible for ensuring that the binary code required to use a service on a remote machine is available on the local host only when required. To support this functionality, a local code base is maintained by discovering and installing code from remote hosts. Since the system is specifically designed for ad hoc networks, it incorporates additional features that help it withstand the inherent dynamism of the network. We present an architecture for our system supporting automatic code management and follow it with a discussion of a Java-based implementation

ComPOS - a Domain-Specific Language for Composing Internet-of-Things Systems

Internet-of-Things (IoT) systems consist of spatially distributed interacting devices. In contrast to desktop applications, IoT systems are always running and need to deal with unresponsive devices and weak connectivity. In this thesis, we propose techniques for simplifying the development of such systems. The work addresses IoT systems organised as reusable services connected by compositions. We propose to program such compositions using stateful reactions that mediate messages. To this end, we have designed a domain-specific language (DSL), called ComPOS. To help systems operate partly in cases of weak connectivity, we propose that ComPOS aborts older reactions when newer messages arrive. We evaluate our DSL in home-automation and e-health scenarios. Understanding IoT systems can be hard, and different analyses can help explain how they work. To support analysis, we propose a conceptual runtime model based on relational reference attribute grammars. We demonstrate the approach by formulating and implementing a Device Dependency Analysis (DDA). The DDA finds sets of devices needed for given parts of the system to work. The ComPOS editor supports live programming to allow development while the system is running. We propose a methodology for live ComPOS programming which divides the development into three, iteratively applied, phases: finding services (explore), composing services (assemble), and abstracting compositions as new services (expose). When developing a DSL, it takes substantial effort to specify the syntax and semantics, to build tools like editors, and to integrate with the environment (in this case the underlying middleware). To reduce the effort needed to experiment with ComPOS, we have created a tool called Jatte. Jatte is a generic projectional editor that developers can tune using attribute grammars. We used Jatte to implement the ComPOS editor