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Third International Workshop on Principles of Engineering Service-Oriented Systems (PESOS 2011), May 23-24, 2011, Waikiki, Honolulu, HI, USA

PESOS 2011 – Proceedings

Contents - Abstracts - Authors

Third International Workshop on Principles of Engineering Service-Oriented Systems (PESOS 2011)

Title Page

Foreword This volume contains the proceedings of the Third Workshop on Principles of Engineering Service-Oriented Systems (PESOS 2011), held in Hawaii, USA on May 23rd and 24th 2011, co-located with ICSE 2011. PESOS is one of the satellite workshops of ICSE that provides a lively and exciting environment for discussion of trends in all aspects of computing that are related to Software Engineering. PESOS 2011 follows the steps of its two predecessors, held in Vancouver (2009) and Cape Town (2010), and aims at exploring the engineering aspects of service-oriented systems. These systems represent a class of software systems in which software is viewed and used as external, loosely-coupled services rather than being physically integrated and owned permanently. Service-oriented systems provide a flexible approach to software development, provisioning, and maintenance because services offer reusable functionality that can be combined to support business processes (or similar) that are dynamic in nature. This enables systems to adapt to changes in their environment as well as to the continuously evolving requirements that are commonplace today. However, service orientation poses challenges to more traditional approaches to software development, stemming from the lack of homogeneity of its basic components and from the requirement to accommodate changes and evolution right from the beginning. The goal of this workshop is to find possibilities of synergy between Software Engineering and Service-Oriented Computing that are beneficial to both fields. In organizing this workshop, we sought to bring together practitioners from both communities for a fruitful exchange of opinions, expertise and experiences. PESOS 2011 was fortunate to have invited talks from experts in the field and a panel on the future of research in service-oriented systems engineering. In addition, nine out of nineteen submitted papers were selected for presentation in four technical sessions. We want to thank the program committee and the additional reviewers for their dedication and the excellent work performed, without which the workshop would not have been possible. We also want to extend our gratitude to the organizers of ICSE 2011 for the facilities they gave us regarding the logistics of the workshop and the publication of the proceedings. Last, we would like to thank two important efforts which were instrumental in materializing PESOS 2011: the contribution of the CMU Software Engineering Institute which started in 2007 a program to develop a taxonomy for SOA research challenges which was reflected in the SDSOA workshops, and the support of the S-Cube European Network of Excellence, which since 2008 has been aligning the effort of over 70 researchers and 50 Ph.D. students and reshaping research agendas of 16 top-level EU academic institutions. Up-to-date information on the workshop can be found at: http://www.s-cube-network.eu/pesos-2011 March 2011 Manuel Carro Dimka Karastoyanova Grace Lewis Anna Liu ORGANIZING COMMITTEE Manuel Carro, School of Computer Science, Technical University of Madrid, Spain. Dimka Karastoyanova, Institute of Architecture of Application Systems (IAAS), University of Stuttgart, Germany. Grace Lewis, Software Engineering Institute, Carnegie Mellon University, U.S.A. Anna Liu, NICTA, Australia. STEERING COMMITTEE Schahram Dustdar, Technical University of Vienna, Austria Carlo Ghezzi, Politecnico di Milano, Italy Domenico Laforenza, IIT‐CNR & ISTI CNR, Italy Frank Leymann, University of Stuttgart, Germany Mike Papazoglou, Tilburg University, The Netherlands Klaus Pohl, University of Duisburg‐Essen, Germany PROGRAM COMMITTEE Vasilios Andrikopoulos, Tilburg University, Netherlands Matthias Book, PALUNO, Germany Antonio Brogi, University of Pisa, Italy Marlon Dumas, University of Tartu, Estonia Schahram Dustdar, TU Vienna, Austria Sam Guinea, Politecnico di Milano, Italy Robert D Johnson, IBM Software Group, USA Raman Kazhamiakin, Fondazione Bruno Kessler (FBK), Italy Marin Litoiu, York University, Canada Nicolás López, University of Los Andes, Colombia Hanan Lutfiyya, University of Western Ontario, Canada Andreas Metzger, PALUNO, Germany Cornelius Ncube, Bournemouth University, UK Elisabetta di Nitto, Politecnico di Milano, Italy Liam O'Brien, CSIRO, Australia Flavio Oquendo, University of South Britain, France Cesare Pautasso, Università della Svizzera Italiana, Switzerland Antonio Ruiz-Cortés, University of Seville, Spain Tarja Systä, Tampere University of Technology, Finland Ladan Tahvildari, University of Waterloo, Canada Ingo Weber, University of New South Wales, Australia ADDITIONAL REVIEWERS Amador Duran Achille Peternier Manuel Resinas Eric Schmieders Sergio Segura Martin Treiber
Tweetflows - Flexible Workflows with Twitter
Martin Treiber, Daniel Schall, Schahram Dustdar, and Christian Scherling
(Vienna University of Technology, Austria; ikangai solutions, Austria)
We present a lightweight coordination and collaboration platform, intertwining contemporary social networking platforms and SOA principles. The idea of our approach is to use Twitter as a platform for collaborations of human and software services in the context of workflows. We introduce primitives that provide SOA functionality like service discovery or service binding and illustrate how these primitives are embedded in Tweets. By using Tweets, we are able to reuse existing infrastructures and tools (e.g., twitter clients on mo- bile devices) for the communication between services and humans. Simultaneously, we exploit social network structures originating from Twitter follower networks in order to discover (human and software) resources that are required for the execution of a workflow. Finally, we are able to monitor the execution of workflows with Twitter, simply by following Tweets that represent the execution of a workflow.
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From Textual Use Cases to Service Component Models
Zuohua Ding, Mingyue Jiang, and Jens Palsberg
(Zhejiang Sci-Tech University, China; UC Los Angeles, USA)
There is a gap between system requirements described with natural language and system design models described with formal language. In this paper, we present a framework for automatically mapping textual use cases to service component models from a model-based point of view. The generated models capture service component signatures and language independent dynamic behaviors. We have implemented our framework and demonstrated the benefits via a case study.
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Engineering Multi-Tenant Software-as-a-Service Systems
Bikram Sengupta and Abhik Roychoudhury
(IBM Research, India; National University of Singapore, Singapore)
Increasingly, Software-as-a-Service (SaaS) is becoming a dominant mechanism for the consumption of software by end users. From a vendor’s perspective, the benefits of SaaS arise from leveraging economies of scale, by serving a large number of customers (“tenants”) through a shared instance of a centrally hosted software service. Consequently, a SaaS provider would, in general, try to drive commonality amongst the requirements of different tenants, and at best, offer a fixed set of customization options. However, many tenants would also come with custom requirements, which may be a pre-requisite for them to adopt the SaaS system. These requirements should then be addressed by evolving the SaaS system in a controlled manner, while still supporting the needs of existing tenants. This need to balance tenant variability and commonality, and to optimize on development and testing effort, can make the evolution of multi-tenant SaaS systems an interesting engineering challenge; this has strong economic undertones as well, given the “pay-per-use” subscription model of SaaS, and the cost of incremental development and maintenance to cater to new tenant needs. In this paper, we outline a set of research issues in the design, testing and maintenance of multi-tenant SaaS systems, and highlight some of the interesting optimization questions that arise in the process. Presenting specific technical solutions is beyond the scope of this paper – instead, our goal is to help shape a research agenda for multi-tenant SaaS that can provide stimulus for further investigation into this area by the software and service engineering research community.
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Towards Efficient Measuring of Web Services API Coverage
Waldemar Hummer, Orna Raz, and Schahram Dustdar
(Vienna University of Technology, Austria; IBM Haifa Research Lab, Israel)

We address the problem of interface-based test coverage for Web services. We suggest an approach to analyze the Application Programming Interface (API) of Web services, calculate the number of possible input combinations and compare it to the number of actual historical invocations. Such API coverage metrics are an indicator to which extent the service has been used. Measuring API coverage is a key concern for assessing the significance of Verification and Validation (V&V) techniques; on the other hand, API coverage metrics can also yield interesting usage reports for a service-based system in production use. The coverage metrics rely on the exact specification of service interfaces, and we provide a mechanism to specify restrictions for data types in the Java Web services framework (JAX-WS). As full enumeration of all possible inputs is often infeasible, we allow the definition of custom coverage metrics by means of domain partitioning: the user divides domain ranges into subsets, and a coverage of 100

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Evaluating the Compatibility of Conversational Service Interactions
Sam Guinea and Paola Spoletini
(Politecnico di Milano, Italy; Università dell'Insubria, Italy)
Service-oriented systems live in an open world, one in which their functionality and quality of service depend on how the services they interact with evolve. System adaptation has been indicated as a way to cope with the evolution these partner services may have. When a partner does not behave as expected, in an adaptable system we can substitute it with an alternative compatible one. Finding a compatible alternative, however, is a difficult task if we consider conversational services that impose a specific interaction protocol and specific data-types. In this paper we introduce Interaction Sequence Charts (ISC) as an effective notation for describing the interactions a service has with its partners, and an algorithm that uses these charts to establish a “degree of compatibility” between interacting services. The algorithm considers both interaction protocol requirements and data-type similarity, for which fuzzy techniques are adopted. The expressive power of ISC is validated by using it to describe the complex behaviour that can be defined using BPEL 2.0, while the algorithm is validated on an example in the field of Tele-Radiology, and shown to be advantageous in practice.
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SMaRT: A Workbench for Reporting the Monitorability of Services from SLAs
Howard Foster and George Spanoudakis
(City University London, UK)
Service Level Agreements (SLAs) for Software Services aim to clearly identify the service level commitments established between service requesters and providers. A dynamic configuration for the monitoring of these SLAs provides the opportunity for service monitor providers to offer and release monitoring infrastructures for different types of services. Whilst there has been work on automating this monitor matching and configuration, additional support may be needed in the negotiation and provision of monitors for which the current monitoring infrastructure does not provide suitable SLA term monitors. In this paper we describe an approach to effectively report and assist service monitoring support groups in managing this provision. The approach described is illustrated with mechanical support in the form of a SMaRT Workbench Eclipse IDE plug-in for reporting on the monitorability of SLAs for service monitoring infrastructures.
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Identifying, Modifying, Creating, and Removing Monitor Rules for Service Oriented Computing
Ricardo Contreras and Andrea Zisman
(City University London, UK)
Monitoring of service-based systems is considered an important activity to support service-oriented computing. Monitoring can be used to verify the behavior of a service-based system, and the quality and contextual aspects of the services participating in the system. Existing approaches for monitoring service-based systems assume that monitor rules are pre-defined and known in advance, which is not always the case. We present a pattern-based HCI-aware monitor adaptation framework to support identification, modification, creation, and removal of monitor rules based on user’s interaction with a service-based system and different types of user context. A prototype tool has been implemented to demonstrate the framework.
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Business Process Performance Prediction on a Tracked Simulation Model
Andrei Solomon and Marin Litoiu
(York University, Canada)
Business processes need to achieve key performance indicators with minimum resources in changing operating conditions. Changes include hardware and software failures, load variation and variations in user interaction with the system. By incorporating simulation in the prediction model it is possible to predict with more confidence system performance degradations. We present our dynamic predictive model which uses forecasting techniques on historical process performance estimates for business process optimization. The parameters of the simulation model are estimates tuned at run-time by tracking the system with a particle filter.
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Architecture-based Reliability Analysis of Web Services in Multilayer Environment
M. Rahmani, A. Azadmanesh, and Harvey Siy
(University of Nebraska-Omaha, USA)
The reliability analysis of web services is often focused on the web service components, ignoring the impact of the middleware located beneath the web services. A service-based software system is a multilayered system that includes the web service (WS), shared resources, and the hosting application server (AS). It is conjectured that the reliability prediction of the web services is improved if the reliability model accounts for such underlying layers. The initial experiment illustrates that the AS and shared resources can impact the overall reliability of web services greatly. This observation is demonstrated by simulating the interaction between a web service and the AS.
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