Abstract. Many applications operate in heterogeneous wireless sensor networks, which represent a challenging programming environment due to the wide range of device capabilities. Servilla addresses this difficulty in developing applications by offering a new middleware framework based on service provisioning. Using Servilla, developers can construct platform-independent applications over a dynamic and diverse set of devices. A salient feature of Servilla is its support for the discovery and binding to local and remote services, which enables flexible and energy-efficient in-network collaboration among heterogeneous devices. Furthermore, Servilla provides a modular middleware architecture that can be easily tailored to devices with a wide range of resources, allowing resource-constrained devices to provide services while leveraging the capabilities of more powerful devices. Servilla has been implemented on TinyOS for two representative hardware platforms (Imote2 and TelosB) with drastically different resources. Microbenchmarks demonstrate the efficiency of Servilla’s implementation, while an application case study on structural health monitoring demonstrates the efficacy of its coordination model for integrating heterogeneous devices. 1

Abstract. Existing architectures for multiagent systems emphasize low-level messaging-related considerations. As a result, the programming abstractions they provide are also low level. In recent years, commitments have been applied to support flexible interactions among autonomous agents. We present a layered multiagent system architecture based on commitments. In this architecture, agents are the components, and the interconnections between the agents are specified in terms of commitments, thus abstracting away from low level details. A crucial layer in this architecture is a commitment-based middleware that plays a vital role in ensuring interoperation and provides commitment-related abstractions to the application programmer. Interoperation itself is defined in terms of commitment alignment. This paper details various aspects of this architecture, and shows how a programmer would write applications to such an architecture. 1

Choreography conformance and contract compliance have been widely studied in the context of synchronous communication. In this paper we approach a more realistic scenario in which the messages containing the invocations are queued in the called service. More precisely, we study the foundational aspects of contract compliance in a language independent way by just taking contracts to be finite labeled transition systems. Then, we relate the proposed theory of contract compliance with choreography specifications à la WS-CDL where activities are interpreted as pairs of send and receive events. An interesting consequence of adopting a language independent representation of contracts is that choreography projection can be defined in structured operational semantics.

Many real-world applications of multiagent systems require independently designed (heterogeneous) and operated (autonomous) a-gents to interoperate. We consider agents who offer business services and collaborate in interesting business service engagements. We formalize notions of interoperability and conformance, which appropriately support agent heterogeneity and autonomy. With respect to autonomy, our approach considers the choices that each agent has, and how their choices are coordinated so that at any time one agent leads and its counterpart follows, but with initiative fluidly shifting among the participants. With respect to heterogeneity, we characterize the variations in the agents ’ designs, and show how an agent may conform to a specification or substitute for another agent. Our approach addresses a challenging problem with multiparty interactions that existing approaches cannot solve. Further,

The IST-FET Integrated Project SENSORIA is developing a novel comprehensive approach to the engineering of service-oriented software systems where foundational theories, techniques and methods are fully integrated into pragmatic software engineering processes. The techniques and tools of SEN-SORIA encompass the whole software development cycle, from business and architectural design, to quantitative and qualitative analysis of system properties, and to transformation and code generation. The SENSORIA approach takes also into account reconfiguration of service-oriented architectures (SOAs) and re-engineering of legacy systems. In this paper we give first a short overview of SENSORIA and then present a pattern language for augmenting service engineering with formal analysis, transformation and dynamicity. The patterns are designed to help software developers choose appropriate tools and techniques to develop service-oriented systems with support from formal methods. They support the whole development process, from the modelling stage to deployment activities and give an overview of many of the research areas pursued in the SENSORIA project.

Abstract. In the context of Web services, making client and service interact so as to satisfy the client, that is, making the service compliant with the client, can be done using either orchestration or choreography. In this paper we propose to build, whenever possible, memoryless orchestrators, and then distribute them using protocols so as to obtain choreographies. When necessary for guaranteeing compliance, we infer from the initial (sequential) transition system possible concurrency between certain interactions, whose validity must be checked by the designer. Our approach allows for a clear distinction between the design phase and the implementation phase while being, in the general case, more efficient than orchestration. An example dealing with resource management illustrates the usefulness of memoryless orchestrators. We also discuss a methodology allowing contract-based design and verification of Web services at a higher level of abstraction. 1

The expanding interest in the modeling and enactment of service engagements creates fresh challenges for software engineering. Existing work on “technical” services, such as on web and grid services, bears little relationship to real-life “business ” services that we consider here. Conventional software engineering is ill-equipped to deal with distributed information systems comprised of autonomous entities representing the business partners involved in a typical service engagement. Although many have recognized the importance of communication in the modeling and enactment of distributed systems, existing approaches treat communication at a low level. Specifically, existing messagingbased approaches consider the flow, but not the meanings, of the messages. Thus they can facilitate interoperation only at a correspondingly low level. In contrast, we give primacy to the meanings of the messages exchanged, based on the notion of commitments. Doing so yields a new high-level notion of interoperability, which we term alignment. We propose a distributed (locally executable) method that guarantees the alignment of business partners despite asynchrony.

Abstract. Choreographies and Contracts are important concepts in Service Oriented Computing. Choreographies are the description of the behaviour of a service system from a global point of view, while contracts are the description of the externally observable message-passing behaviour of a given service. Exploiting some of our previous results about choreography projection and contract refinement, we show how to solve the problem of implementing a choreography via the composition of already available services that are retrieved according to their contracts.

journal homepage: www.elsevier.com/locate/scico Servilla: A flexible service provisioning middleware for heterogeneous

Abstract—We present a vision for future research on an emerging topic in software engineering, namely the synergy between Software Product Line Engineering (SPLE) and Service-Oriented Computing (SOC). Our aim is to develop rigorous modelling techniques and analysis and verification tools that can be used for the systematic, large-scale provision and market segmentation of software services. We foresee flexible design techniques with which software service line organizations can develop novel classes of service-oriented applications that can easily be adapted to customer requirements as well as to changes in the context in which, and while, they execute. By superposing variability mechanisms on current languages for service design, based on policies and strategies defined by service providers, we envision the possibility to identify variability points that can be triggered at run time to increase adaptability and optimize the (re)use of resources. I.