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2012 4th International Workshop on Principles of Engineering Service-Oriented Systems (PESOS), June 4, 2012, Zurich, Switzerland

PESOS 2012 – Proceedings

Contents - Abstracts - Authors

4th International Workshop on Principles of Engineering Service-Oriented Systems (PESOS)

Preface

Title Page

Foreword
The goal of PESOS 2012 is to bring together software engineering researchers from academia and industry, as well as practitioners working in the areas of service-oriented systems, to discuss research challenges, recent developments, novel application scenarios, as well as methods, techniques, experiences and tools to support engineering, evolution and adaptation of large-scale, highly-dynamic service-oriented systems.

Agile Deployment of Service-Oriented Systems

Simulating Awareness in Global Software Engineering: A Comparative Analysis of Scrum and Agile Service Networks
Damian A. Tamburri, Ivan S. Razo-Zapata, Héctor Fernández, and Cédric Tedeschi
(VU University Amsterdam, Netherlands; IRISA, France; University of Rennes 1, France; INRIA, France)
Global software engineering (GSE) is a business strategy to realize a business idea (i.e. the development project) faster, through round-the-clock productivity. However, GSE creates a volatile and unstable process in which many actors interact together against unpredictable premises (e.g. cultural or time differences), often producing unexpected outcomes (e.g. compacting effects of distance and time). So far, Scrum has been used extensively for embarking in global software engineering, but many of the problems in Scrum-based GSE could still benefit from the usage of ad-hoc supporting tools (e.g. information continuity between timezones, cultural differences, developers awareness, etc.). Agile Service Networks (ASNs) are networks of service oriented applications (nodes) that collaborate adaptively towards a common goal. ASNs offer a way to represent GSE professionals through service-oriented “social” nodes in a “small-world” network (much like a Facebook for a specific GSE project). This paper presents a comparison between the two approaches, namely Scrum and ASNs, to determine ASN’s potentials as mechanisms to maintain awareness in GSE.
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Non-functional Analysis of Service Choreographies
Cesare Bartolini, Antonia Bertolino, Guglielmo De Angelis, Andrea Ciancone, and Raffaela Mirandola
(ISTI-CNR, Italy; Politecnico di Milano, Italy)
A highly important aspect in service compositions is to guarantee the established Quality-of-Service (QoS). However, the modeling of non-functional properties of service choreographies is neglected in the OMG standard BPMN notation, so that other, separate languages should be used to specify QoS constraints and then traced back to the functional BPMN model. We introduced an approach called Q4BPMN by which non-functional requirements can be directly expressed within the BPMN model. This paper leverages Model Driven Engineering (MDE) techniques to automatically handle non-functional properties expressed with Q4BPMN in order to obtain information useful both to highlight intrinsic features of the service choreography and to detect possible model criticalities. Specifically, we transform a Q4BPMN model into the pivot KLAPER notation, on which we can directly exploit the analysis tools within the KLAPERSUITE environment. Hence this paper provides the first step towards automated non-functional analysis of service choreographies.
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Dependability-Driven Runtime Management of Service Oriented Architectures
Hanen Haouas and Johann Bourcier
(INRIA, France; IRISA, France; University of Rennes 1, France)
Software systems are becoming more and more complex due to the integration of large scale distributed entities and the continuous evolution of these new infrastructures. All these systems are progressively integrated in our daily environment and their increasing importance have raised a dependability issue. While Service oriented architecture is providing a good level of abstraction to deal with the complexity and heterogeneity of these new infrastructures, current approaches are limited in their ability to monitor and ensure the system dependability. In this paper, we propose a framework for the autonomic management of service oriented application based on a dependability objective. Our framework proposes a novel approach which leverages peer to peer evaluation of service providers to assess the system dependability. Based on this evaluation, we propose various strategies to dynamically adapt the system to maintain the dependability level of the system to the desired objective.
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Local Model Learning for Asynchronous Services
Casandra Holotescu
(Politehnica University of Timisoara, Romania)
Software services are often composed into more complex systems. Existing methods ensure the correctness of service compositions by automatically generating a mediator/adaptor service: a service in the middle to properly coordinate the interactions in the system towards satisfying a desired temporal property. This is accomplished using formal behavioural models for the participating services. However, such models are not always provided, which makes it difficult to compose systems containing incompletely specified services. We developed a black-box model learning method specifically adapted for stateful asynchronous services. Often, such services exhibit uncontrollable behaviour, which is not addressed by current learning techniques. Our technique interleaves runtime exploration with model refinement in order to learn an approximation of the real behaviour that allows for a safe system composition. Furthermore, the service model is learned locally, thus allowing parallelism in the inference process when more than one black-box service model has to be learned. Experiments performed show that obtained models are precise enough to be used for adaptor synthesis.
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SOA Governance

Exploring the Impact of Inaccuracy and Imprecision of QoS Assumptions on Proactive Constraint-Based QoS Prediction for Service Orchestrations
Dragan Ivanović, Manuel Carro, and Manuel Hermenegildo
(TU Madrid, Spain; IMDEA Software Institute, Spain)
Constraint-based Quality of Service (QoS) prediction is a method for predicting violations of Service Level Agreements (SLAs) in an executing instance of a service orchestration. It uses assumptions about the ranges of QoS values for component services in the orchestration. Experiments suggest that the method, when given correct component QoS assumptions, produces highly accurate predictions according to a series of quality-of-prediction metrics, and that it does so well ahead of the time when the prediction is to happen. We study the behavior of this method when the component QoS assumptions become incorrect or too vague. We conclude that the effect is a graceful deterioration in prediction quality, unless gross (order-of-magnitude) imprecisions are introduced. However, the method is very sensitive to the loss of information on the lower bounds for component QoS values, since the knowledge of the upper bounds is not sufficient for failure prediction.
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Managing Mutiple Applications in a Service Platform
Jacky Estublier and German Vega
(Grenoble University, France; LIG, France)
Information hiding and hierarchical decomposition are the corner stone of Software Engineering best practices. These principles have been applied in methods, architectures, programming languages, and run-time platforms. It is therefore a big surprise to notice that the recent dynamic service platforms, like OSGi, do not make use of these principles. In OSGi, all services are visible; a client asking for an interface will be wired to any service, randomly selected and implementing that interface,which makes almost impossible protection and encapsulation. Nevertheless, OSGi is very successful for its almost unique capability to support dynamicity; and because the current practice is to run a single application per platform. Unfortunately, the future of gateways, like OSGi, is to manage the “discovery”, access and control of resources (logical as well as physical (sensors, devices)) shared by many applications. In the near future, OSGi will have to scale from a light weight mono-application gateway to a full-fledged dynamic platform. We have developed a layer on top of OSGi called APlication Abstract Machine (Apam) which provides OSGi dynamic capabilities, but also introduces a composite concept allowing multiple applications to cover the range isolation/collaboration from “black-box” (information hiding and hierarchical decomposition) to “scrambled eggs” as in service platforms, and through a variety of grey and white boxes with variable degrees of collaboration, sharing and control. The paper presents the state of practice, the challenges future dynamic platforms have to address, and how the Apam platform provides a solution to these issues. An assessment of the first Apam experimentations concludes the paper.
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Monitoring Service-Oriented Systems

SALMonADA: A Platform for Monitoring and Explaining Violations of WS-Agreement-Compliant Documents
Carlos Müller, Marc Oriol, Marc Rodríguez, Xavier Franch, Jordi Marco, Manuel Resinas, and Antonio Ruiz-Cortés
(University of Seville, Spain; Universitat Politècnica de Catalunya, Spain)
Quality assurance techniques have been developed to supervise the service quality (QoS) agreed between service-based systems (SBSs) consumers and providers. Such QoS is usually included in service level agreements (SLAs) and thus, SLA monitoring platforms have been developed supporting violation detection. However, just a few of them provide explanation of the violations caused by observed QoS at monitoring time, but not in an user-friendly format. Therefore, we propose a general monitoring and analysis conceptual reference model and we instantiated it with SALMonADA, a SBS that notifies the clients with violations and their causes in their own easy-to-understand specification terms. In addition, our platform performs an early analysis notification that avoids delays in the client notification time when a violation takes place. Moreover, we have implemented a web application as a SALMonADA client, to prove how it monitors, analyses and reports to their clients the service level fulfillment of real services subject to a SLA specified with WS-Agreement.
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PRadapt: A Framework for Dynamic Monitoring of Adaptable Service-Based Systems
Ricardo Contreras, Andrea Zisman, Annapaola Marconi, and Marco Pistore
(City University London, UK; Fondazione Bruno Kessler, Italy)
Existing approaches for monitoring service-based systems assume that monitor rules are pre-defined and known in advance. However, adaptation of service-based systems may trigger the need to adapt the associated monitor rules in order to verify the correct behavior of the adapted service compositions. In this work, we present PRadapt, a framework for dynamic monitoring of adaptable service-based systems that supports the run-time identification, creation, modification and removal of monitor rules as a reaction to changes in the context and the system
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The Quest for Case Studies

Spicy Stonehenge: Proposing a SOA Case Study
Tiago Espinha, Cuiting Chen, Andy Zaidman, and Hans-Gerhard Gross
(TU Delft, Netherlands)
Maintenance research in the context of Service Oriented Architecture (SOA) is currently lacking a suitable standard case study that can be used by scientists in order to (1) develop and assess their research ideas and (2) compare and benchmark their solution(s). It is also well established in different fields that having such a standard case study system brings many benefits, in that it helps determine which approaches work best for specific problems. For this reason, we decided to build upon an existing open-source system and make it available for other researchers to use. This system is Spicy Stonehenge.
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Open SOALab: Case Study Artifacts for SOA Research and Education
Norman Wilde, John Coffey, Thomas Reichherzer, and Laura White
(University of West Florida, USA)
Both SOA researchers and SOA educators need simple example systems for case studies and courseware. Open SOALab provides three such documented applications which are available for download. This paper briefly describes the applications and some of the case studies and educational activities that have used them.
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Constraint-Based Invocation of Stateful Web Services: The Beep Store (Case Study)
Sylvain Hallé and Roger Villemaire
(Université du Québec à Chicoutimi, Canada; Université du Québec à Montréal, Canada)
Shopping cart manipulations are a prime example of web services exhibiting stateful behaviour. The Beep Store is a web service synthesizing past work on the study and formalization of stateful interface constraints, and presenting many of the characteristics found in real-world web services, such as Amazon's and PayPal shopping carts.
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Cloud in a Cloud for Cloud Education
Shigetoshi Yokoyama, Nobukazu Yoshioka, and Takahiro Shida
(National Institute of Informatics, Japan; NTT DATA Intellilink, Japan)
the proper education of engineers will be crucial for the continued development of cloud technologies. We have developed a cloud called edubase Cloud for information technology education. In this paper, we discuss how edubase Cloud supports cloud educational materials through a case study and how effective it is for educating cloud engineers.
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A Car Logistics Scenario for Context-Aware Adaptive Service-Based Systems
Antonio Bucchiarone, Nawaz Khurshid, Annapaola Marconi, Marco Pistore, and Heorhi Raik
(Fondazione Bruno Kessler, Italy)
We present a logistic scenario, based on the sea port of Bremen, and a context-aware dynamic service-based system to support its operation. We also show how we have used it to evaluate our automated adaptation techniques.
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A Monitoring Data Set for Evaluating QoS-Aware Service-Based Systems
Philipp Leitner, Waldemar Hummer, and Schahram Dustdar
(Vienna University of Technology, Austria)
Research in service-oriented computing traditionally struggles with the absence of public cases and data sets for evaluating and comparing research results. This is particularly evident for QoS-aware service-based computing, where public and widely accepted QoS traces would help to strengthen the fair comparison of QoS-aware automated composition and QoS prediction approaches. In this paper, we present one public data set produced for the evaluation of a contribution to the IEEE Transactions on Services Computing journal. We briefly introduce the background story of the use case and describe our monitored data set. We hope that this data set can serve as a basis for evaluation of future research papers from other authors.
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Providing Lightweight and Adaptable Service Technology for Information and Communication (PLASTIC) in the Mobile eHealth Case Study
Marco Autili, Luca Berardinelli, Davide Di Ruscio, and Catia Trubiani
(University of L'Aquila, Italy)
In this paper we briefly describe a case study, i.e. the Mobile eHealth (MeH), developed in the context of the IST PLASTIC project aimed at supporting self-adapting and context-aware services. The goal of the case study is to show how to model a service-based application and to demonstrate that model-based solutions are suitable to generate Quality of Service (QoS) models and adaptable code from service models.
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