Test Sequences for Web Service Composition using CPN model

Web service composition is most mature and effective way to realize the rapidly changing requirements of business in service-oriented solutions. Testing the compositions of web services is complex, due to their distributed nature and asynchronous behaviour. Colored Petri Nets (CPNs) provide a framework for the design, specification, validation and verification of systems. In this paper the CPN model used for composition design verification is reused for test design purpose. We propose an on-the-fly algorithm that generates a test suite that covers all possible paths without redundancy.  The prioritization of test sequences, test suite size and redundancy reduction are also focused. The proposed technique was applied to air line reservation system and the generated test sequences were evaluated against three coverage criteria; Decision Coverage, Input Output Coverage and Transition Coverage. Keywords— CPN, MBT, web service composition testing, test case generatio

Enhancing coverage adequacy of service compositions after runtime adaptation

Laufzeitüberwachung (engl. runtime monitoring) ist eine wichtige Qualitätssicherungs-Technik für selbstadaptive Service-Komposition. Laufzeitüberwachung überwacht den Betrieb der Service-Komposition. Zur Bestimmung der Genauigkeit von Software-Tests werden häufig Überdeckungskriterien verwendet. Überdeckungskriterien definieren Anforderungen die Software-Tests erfüllen muss. Wegen ihrer wichtigen Rolle im Software-Testen haben Forscher Überdeckungskriterien an die Laufzeitüberwachung von Service-Komposition angepasst. Die passive Art der Laufzeitüberwachung und die adaptive Art der Service-Komposition können die Genauigkeit von Software-Tests zur Laufzeit negativ beeinflussen. Dies kann jedoch die Zuversicht in der Qualität der Service-Komposition begrenzen. Um die Überdeckung selbstadaptiver Service-Komposition zur Laufzeit zu verbessern, untersucht diese Arbeit, wie die Laufzeitüberwachung und Online-Testen kombiniert werden können. Online-Testen bedeutet dass Testen parallel zu der Verwendung einer Service-Komposition erfolgt. Zunächst stellen wir einen Ansatz vor, um gültige Execution-Traces für Service-Komposition zur Laufzeit zu bestimmen. Der Ansatz berücksichtigt die Execution-Traces von Laufzeitüberwachung und (Online)-Testen. Er berücksichtigt Änderungen im Workflow und Software-Services eines Service-Komposition. Zweitens, definieren wir Überdeckungskriterien für Service-Komposition. Die Überdeckungskriterien berücksichtigen Ausführungspläne einer Service-Komposition und berücksichtigen die Überdeckung für Software-Services und die Service-Komposition. Drittens stellen wir Online-Testfälle Priorisierungs Techniken, um die Abdeckungniveau einer Service-Komposition schneller zu erreichen. Die Techniken berücksichtigen die Überdeckung einer Service-Komposition durch beide Laufzeitüberwachung und Online-Tests. Zusätzlich, berücksichtigen sie die Ausführungszeit von Testfällen und das Nutzungsmodell der Service-Komposition. Viertens stellen wir einen Rahmen für die Laufzeitüberwachung und Online-Testen von Software-Services und Service-Komposition, genannt PROSA, vor. PROSA bietet technische Unterstützung für die oben genannten Beiträge. Wir evaluieren die Beiträge anhand einer beispielhaften Service-Komposition, die häufig in dem Forschungsgebiet Service-oriented Computing eingesetzt wird.Runtime monitoring (or monitoring for short) is a key quality assurance technique for self-adaptive service compositions. Monitoring passively observes the runtime behaviour of service compositions. Coverage criteria are extensively used for assessing the adequacy (or thoroughness) of software testing. Coverage criteria specify certain requirements on software testing. The importance of coverage criteria in software testing has motivated researchers to adapt them to the monitoring of service composition. However, the passive nature of monitoring and the adaptive nature of service composition could negatively influence the adequacy of monitoring, thereby limiting the confidence in the quality of the service composition. To enhance coverage adequacy of self-adaptive service compositions at runtime, this thesis investigates how to combine runtime monitoring and online testing. Online testing means testing a service composition in parallel to its actual usage and operation. First, we introduce an approach for determining valid execution traces for service compositions at runtime. The approach considers execution traces of both monitoring and (online) testing. It considers modifications in both workflow and constituent services of a service composition. Second, we define coverage criteria for service compositions. The criteria consider execution plans of a service composition for coverage assessment and consider the coverage of an abstract service and the overall service composition. Third, we introduce online-test-case prioritization techniques to achieve a faster coverage of a service composition. The techniques employ coverage of a service composition from both monitoring and online testing, execution time of test cases, and the usage model of the service composition. Fourth, we introduce a framework for monitoring and online testing of services and service compositions called PROSA. PROSA provides technical support for the aforementioned contributions. We evaluate the contributions of this thesis using service compositions frequently used in service-oriented computing research

Towards runtime discovery, selection and composition of semantic services

Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process

A Framework for the Evaluation of Semantics-based Service Composition Approaches

The benefits of service composition are being largely acknowledged in the literature nowadays. However, as the amount of available services increases, it becomes difficult to manage, discover, select and compose them, so that automation is required in these processes. This can be achieved by using semantic information represented in ontologies. Currently there are many different approaches that support semantics-based service composition. However, still little effort has been spent on creating a common methodology to evaluate and compare such approaches. In this paper we present our initial ideas to create an evaluation framework for semantics-based service composition approaches. We use a collection of existing services, and define a set of evaluation metrics, confusion matrix-based and time-based. Furthermore, we present how composition evaluation scenarios are generated from the collection of services and specify the strategy to be used in the evaluation process. We demonstrate the proposed framework through an example. Currently there are mechanisms and initiatives to address the evaluation of the semantics-based service discovery and matchmaking approaches. However, still few efforts have been spent on the creation of comprehensive evaluation mechanisms for semantics-based service composition approaches

Integrating trait-based empirical and modeling research to improve ecological restoration

A global ecological restoration agenda has led to ambitious programs in environmental policy to mitigate declines in biodiversity and ecosystem services. Current restoration programs can incompletely return desired ecosystem service levels, while resilience of restored ecosystems to future threats is unknown. It is therefore essential to advance understanding and better utilize knowledge from ecological literature in restoration approaches. We identified an incomplete linkage between global change ecology, ecosystem function research, and restoration ecology. This gap impedes a full understanding of the interactive effects of changing environmental factors on the long-term provision of ecosystem functions and a quantification of trade-offs and synergies among multiple services. Approaches that account for the effects of multiple changing factors on the composition of plant traits and their direct and indirect impact on the provision of ecosystem functions and services can close this gap. However, studies on this multilayered relationship are currently missing. We therefore propose an integrated restoration agenda complementing trait-based empirical studies with simulation modeling. We introduce an ongoing case study to demonstrate how this framework could allow systematic assessment of the impacts of interacting environmental factors on long-term service provisioning. Our proposed agenda will benefit restoration programs by suggesting plant species compositions with specific traits that maximize the supply of multiple ecosystem services in the long term. Once the suggested compositions have been implemented in actual restoration projects, these assemblages should be monitored to assess whether they are resilient as well as to improve model parameterization. Additionally, the integration of empirical and simulation modeling research can improve global outcomes by raising the awareness of which restoration goals can be achieved, due to the quantification of trade-offs and synergies among ecosystem services under a wide range of environmental conditions

Taming the cloud: Safety, certification and compliance for software services - Keynote at the Workshop on Engineering Service-Oriented Applications (WESOA) 2011

The maturity of IT processes, such as software development, can be and is often certified. Current trends in the IT industry suggest that software systems in the future will be very different from their counterparts today, with an increasing adoption of the Service-Oriented Architecture (SOA) design pattern and the deployment of Software-as-a-Service (SaaS) on Cloud infrastructures. In this talk we discuss some issues surrounding engineering Software Services for Cloud infrastructures and highlight the need for enhanced control, service-level agreement and compliance mechanisms for Software Services. Cloud Infrastructures and Service Mash-ups

Towards run-time monitoring of web services conformance to business-level agreements

Web service behaviour is currently specified in a mixture of ways, often using methods that are only partially complete. These range from static functional specifications, based on interfaces in WSDL and preconditions in RIF, to business process simulations using executable process-based models such as BPEL, to detailed quality of service (QoS) agreements laid down in a service level agreement (SLA). This paper recognises that something similar to a SLA is required at the higher business level to govern the contract between service producers, brokers and consumers. We call this a business level agreement (BLA) and within this framework, seek to unify disparate aspects of functional specification, QoS and run-time verification. We propose that the method for validating a web service with respect to its advertised BLA should be based on run-time service monitoring. This is a position paper towards defining these goals

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