Building on the theory of modal I/O automata (MIOs) by Larsen et al. we introduce a new compatibility notion called weak modal compatibility. As an important property of behavioral interface theories we prove that weak modal compatibility is preserved under weak modal refinement. Furthermore, we organize and compare different notions of refinement and compatibility to give an easily-accessible overview. Finally, we describe the MIO Workbench, an Eclipse-based editor and verification tool for modal I/O automata, which implements various refinement, compatibility and composition notions and is able to depict the results of verification directly on the graphical representation of MIOsrelations or state pairs in the positive and erroneous paths in the negative case.

The Business Process Execution Language (BPEL) is emerging as the new standard in Web service composition. As more and more workflows are modelled using BPEL, unit-testing these compositions becomes increasingly important. However, little research has been done in this area and no frameworks comparable to the xUnit family are available. In this paper, we propose a layer-based approach to creating frameworks for repeatable, white-box BPEL unit testing, which we use for the development of a new testing framework. This framework uses a specialized BPEL-level testing language to describe interactions with a BPEL process to be carried out in a test case. The framework supports automated test execution and offers test management capabilities in a standardized and open way via welldefined interfaces -even to third-party applications.

No abstract

Autonomic computing - that is, the development of software and hardware systems featuring a certain degree of self-awareness and self-adaptability - is a field with many application areas and many technical difficulties. In this paper, we explore the idea of an autonomic cloud in the form of a platform-as-a-service computing infrastructure which, contrary to the usual practice, does not consist of a well-maintained set of reliable high-performance computers, but instead is formed by a loose collection of voluntarily provided heterogeneous nodes which are connected in a peer-to-peer manner. Such an infrastructure must deal with network resilience, data redundancy, and failover mechanisms for executing applications. We discuss possible solutions and methods which help developing such (and similar) systems. The described approaches are developed in the EU project ASCENS

Software systems based on Service-Oriented Architectures (SOAs) promise high flexibility, improved maintainability, and simple re-use of functionality. A variety of languages and standards have emerged for working with SOA artifacts; however, service computing still lacks an effective and intuitive model-driven approach starting from models written in an established modeling language like UML and, in the end, generating comprehensive executable code. In this paper, we present a conservative extension to the UML2 for modeling service orchestrations at a high level of abstraction, and a fully automatic approach for transforming these orchestrations down to the wellknown Web Service standard BPEL.

Context: Non-trivial software systems are written using multiple (programming) languages, which are connected by cross-language links. The existence of such links may lead to various problems during software development. There is little empirical evidence on the incidence of these problems and the experiences of professional developers in this field. Aim: We want to provide empirical evidence on multi-language software development, cross-language linking, and tool support in industry, including the views of professional developers on benefits and problems in these areas. Methods: We conducted a survey study to gather responses from 139 professional software developers. Results: Respondents reported an average of 7 languages and 3 linked language pairs per project. Respondents saw benefits of multi-language development for the motivation of developers and the translation of requirements, but problems in understandability and changeability. Over 90% of respondents reported problems related to cross-language linking. Developers universally agree on the usefulness of tool support. Conclusions: Multi-language programming and cross-language linking seem common but lead to several problems. We suggest that future practical as well as research efforts focus on these issues by creating appropriate tool support and by developing better techniques for cross-language linking for improved changeability and understandability.

Systems based on the service-oriented architecture (SOA) principles have become an important cornerstone of the development of enterprise-scale software applications. They are characterized by separating functions into distinct software units, called services, which can be published, requested and dynamically combined in the production of business applications. Service-oriented systems (SOSs) promise high flexibility, improved maintainability, and simple re-use of functionality. Achieving these properties requires an understanding not only of the individual artifacts of the system but also their integration. In this context, non-functional aspects play an important role and should be Communicated by analyzed and modeled as early as possible in the development cycle. In this paper, we discuss modeling of non-functional aspects of service-oriented systems, and the use of these models for analysis and deployment. Our contribution in this paper is threefold. First, we show how services and service compositions may be modeled in UML by using a profile for SOA (UML4SOA) and how non-functional properties of service-oriented systems can be represented using the nonfunctional extension of UML4SOA (UML4SOA-NFP) and the MARTE profile. This enables modeling of performance, security and reliable messaging. Second, we discuss formal analysis of models which respect this design, in particular we consider performance estimates and reliability analysis using the stochastically timed process algebra PEPA as the underlying analytical engine. Last but not least, our models are the source for the application of deployment mechanisms which comprise model-to-model and model-to-text transformations implemented in the framework VIATRA. All techniques presented in this work are illustrated by a running example from an eUniversity case study.

Abstract. The popularity of the cloud computing paradigm is opening new opportunities for collaborative computing. In this paper we tackle a fundamental problem in open-ended cloud-based distributed computing platforms, i.e., the quest for potential collaborators. We assume that cloud participants are willing to share their computational resources for shared distributed computing problems, but they are not willing to disclosure the details of their resources. Lacking such information, we advocate to rely on reputation scores obtained by evaluating the interactions among participants. More specifically, we propose a methodology to assess, at design time, the impact of different (reputation-based) collaborator selection strategies on the system performance. The evaluation is performed through statistical analysis on a volunteer cloud simulator.