Big Data Analytics for QoS Prediction Through Probabilistic Model Checking

As competitiveness increases, being able to guaranting QoS of delivered services is key for business success. It is thus of paramount importance the ability to continuously monitor the workflow providing a service and to timely recognize breaches in the agreed QoS level. The ideal condition would be the possibility to anticipate, thus predict, a breach and operate to avoid it, or at least to mitigate its effects. In this paper we propose a model checking based approach to predict QoS of a formally described process. The continous model checking is enabled by the usage of a parametrized model of the monitored system, where the actual value of parameters is continuously evaluated and updated by means of big data tools. The paper also describes a prototype implementation of the approach and shows its usage in a case study.Comment: EDCC-2014, BIG4CIP-2014, Big Data Analytics, QoS Prediction, Model Checking, SLA compliance monitorin

Specification and Verification of Context-dependent Services

Current approaches for the discovery, specification, and provision of services ignore the relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. We remedy this situation in this paper. We present a formal definition of services with context-dependent contracts. We define a composition theory of services with context-dependent contracts taking into consideration functional, nonfunctional, legal and contextual information. Finally, we present a formal verification approach that transforms the formal specification of service composition into extended timed automata that can be verified using the model checking tool UPPAAL.Comment: In Proceedings WWV 2011, arXiv:1108.208

Dynamic integration of context model constraints in web service processes

Autonomic Web service composition has been a challenging topic for some years. The context in which composition takes places determines essential aspects. A context model can provide meaningful composition information for services process composition. An ontology-based approach for context information integration is the basis of a constraint approach to dynamically integrate context validation into service processes. The dynamic integration of context constraints into an orchestrated service process is a necessary direction to achieve autonomic service composition

Towards a Security, Privacy, Dependability, Interoperability Framework for the Internet of Things

A popular application of ambient intelligence systems constitutes of assisting living services on smart buildings. As intelligence is imported in embedded equipment, the system becomes able to provide smart services (e.g. control lights, airconditioning, provide energy management services etc.). IoT is the main enabler of such environments. However, the interconnection of these cyber-physical systems and the processing of personal data raise serious security and privacy issues. In this paper we present a framework that can guarantee Security, Privacy, Dependability and Interoperability (SPDI) in IoT. Taking advantage of the underlying IoT deployment, the proposed framework not only implements the requested smart functionality but also provide modelling and administration that can guarantee those SPDI properties. Moreover, we provide an application example of the framework in a smart building scenario

A design method for modular energy-aware software

Nowadays achieving green software by reducing the overall energy consumption of the software is becoming more and more important. A well-known solution is to make the software energy-aware by extending its functionality with energy optimizers, which monitor the energy consumption of software and adapt it accordingly. Modular design of energy-aware software is necessary to make the extensions manageable and to cope with the complexity of the software. To this aim, we require suitable methods that guide designers through the necessary design activities and the models that must be prepared during each activity. Despite its importance, such a method is not investigated in the literature. This paper proposes a dedicated design method for energy-aware software, discusses a concrete realization of this method, and—by means of a concrete example—illustrates the suitability of this method in achieving modularity

Quantifiable non-functional requirements modeling and static verification for web service compositions

As service oriented architectures have become more widespread in industry, many complex web services are assembled using independently developed modular services from different vendors. Although the functionalities of the composite web services are ensured during the composition process, the non-functional requirements (NFRs) are often ignored in this process. Since quality of services plays a more and more important role in modern service-based systems, there is a growing need for effective approaches to verifying that a composite web service not only offers the required functionality but also satisfies the desired NFRs. Current approaches to verifying NFRs of composite services (as opposed to individual services) remain largely ad-hoc and informal in nature. This is especially problematic for high-assurance composite web services. High-assurance composite web services are those composite web services with special concern on critical NFRs such as security, safety and reliability. Examples of such applications include traffic control, medical decision support and the coordinated response systems for civil emergencies. The latter serves to motivate and illustrate the work described here. In this dissertation we develop techniques for ensuring that a composite service meets the user-specified NFRs expressible as hard constraints, e.g., the messages of particular operations must be authenticated. We introduce an automata-based framework for verifying that a composite service satisfies the desired NFRs based on the known guarantees regarding the non-functional properties of the component services. This automata-based model is able to represent NFRs that are hard, quantitative constraints on the composite web services. This model addresses two issues previously not handled in the modeling and verification of NFRs for composite web services: (1) the scope of the NFRs and (2) consistency checking of multiple NFRs. A scope of a NFR on a web service composition is the effective range of the NFR on the sub-workflows and modular services of the web service composition. It allows more precise description of a NFR constraint and more efficient verification. When multiple NFRs exist and overlap in their scopes, consistency checking is necessary to avoid wasted verification efforts on conflicting constraints. The approach presented here captures scope information in the model and uses it to check the consistency of multiple NFRs prior to the static verification of web service compositions. We illustrate how our approach can be used to verify security requirements for an Emergency Management System. We then focus on families of highly-customizable, composed web services where repeated verification of similar sets of NFRs can waste computation resources. We introduce a new approach to extend software product line engineering techniques to the web service composition domain. The resulting technique uses a partitioning similar to that between domain engineering and application engineering in the product-line context. It specifies the options that the user can select and constructs the resulting web service compositions. By first creating a web-service composition search space that satisfies the common requirements and then querying the search space as the user makes customization decisions, the technique provides a more efficient way to verify customizable web services. A decision model, illustrated with examples from the emergency-response application, is created to interact with the customers and ensure the consistency of their specifications. The capability to reuse the composition search space is shown to improve the quality of the composite services and reduce the cost of re-verifying the same compositions. By distinguishing the commonalities and the variabilities of the web services, we divide the web composition into two stages: the preparation stage (to construct all commonalities) and the customization stage (to choose optional and alternative features). We thus draw most of the computation overhead into the first stage during the design in order to enable improved runtime efficiency during the second stage. A simulation platform was constructed to conduct experiments on the two verification approaches and three strategies introduced in this dissertation. The results of these experiments were analyzed to show the advantage of our automaton-based model in its verification efficiency with scoping information. We have shown how to choose the most efficient verification strategy from the three strategies of verifying multiple NFRs introduced in this dissertation under different circumstances. The results indicate that the software product line approach has significant efficiency improvement over traditional on-demand verification for highly customizable web service compositions

Systematic composition of distributed objects: Processes and sessions

We consider a system with the infrastructure for the creation and interconnection of large numbers of distributed persistent objects. This system is exemplified by the Internet: potentially, every appliance and document on the Internet has both persistent state and the ability to interact with large numbers of other appliances and documents on the Internet. This paper elucidates the characteristics of such a system, and proposes the compositional requirements of its corresponding infrastructure. We explore the problems of specifying, composing, reasoning about and implementing applications in such a system. A specific concern of our research is developing the infrastructure to support structuring distributed applications by using sequential, choice and parallel composition, in the anarchic environment where application compositions may be unforeseeable and interactions may be unknown prior to actually occurring. The structuring concepts discussed are relevant to a wide range of distributed applications; our implementation is illustrated with collaborative Java processes interacting over the Internet, but the methodology provided can be applied independent of specific platforms

XSRL: An XML web-services request language

One of the most serious challenges that web-service enabled e-marketplaces face is the lack of formal support for expressing service requests against UDDI-resident web-services in order to solve a complex business problem. In this paper we present a web-service request language (XSRL) developed on the basis of AI planning and the XML database query language XQuery. This framework is designed to handle and execute XSRL requests and is capable of performing planning actions under uncertainty on the basis of refinement and revision as new service-related information is accumulated (via interaction with the user or UDDI) and as execution circumstances necessitate change