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According to market research, the number of smart cities is increasing rapidly. Information and communication technologies (ICT) provide the smart infrastructure that is the foundation for all the key themes related to a smart city, such as smart economy, smart governance, smart mobility, smart health, smart buildings, and smart water. As such, a smart city is constituted of various infrastructure components that form a complex system of systems, which is essential to collaborate effectively. Services play a central role in this vision of smart cities, as they are used as building blocks for effective collaboration, i.e., to achieve interoperability between heterogeneous parties and independence from the underlying infrastructure. In order to cope with the problem of complexity and the scalability in smart cities' systems, a solution is to provide autonomous, collaborating services that have situation awareness and are able to adapt dynamically to the changing needs of the environment forming a nexus of services. In this research, we propose a nexus model for smart cities' services collaboration by using the role modeling approach enhanced by the introduction of service teamwork roles. The teamwork roles definition is inspired both by human and agent team working models. We determine the dominant teamwork roles that prevail during service group cooperation, where the main goal of each role is to intervene and "act as a connector" during collaboration to keep the team of component services consistent with the goal of the group–team. The teamwork functionality is applied through the introduction of a new layer in the architecture of smart cities and is exploited to overcome some of the aforementioned problems. A case study that presents how teamwork roles could affect and benefit the service collaboration in a smart city environment is also provided. [ABSTRACT FROM AUTHOR]

Automated composition of Web services is becoming a prominent paradigm for implementing and delivering distributed applications. A composed service can be described either by orchestration or choreography. Service orchestration has a centralized controller which coordinates the services in a composite service. Differently, service choreography assumes that all of the participating services collaborate with each other to achieve a globally shared task. Choreography has received great attention and demonstrated a few key advantages over orchestration such as data efficiency, distributed control, and scalability. Although there is extensive research on the languages and protocols of choreography, automated design of choreography plans, especially distributed plans for multiple roles, is more complex and not studied before. In this paper, we propose a novel planning-based approach, including compilation of contingencies, stateful actions, dependency analysis and communication control, which can automatically convert a given composition task to a distributed choreography specification. The experimental results conducted on large scale service repositories show the effectiveness and efficiency of our approach for automated choreography of Web services. [ABSTRACT FROM AUTHOR]

Service-based applications are based on modern architectures that require careful design of interfaces and protocols to allow smooth integration of service components. These design artifacts are not only useful for implementation, but could also be used for the derivation of integration tests. In order to be applied in these different activities of the development process, they have to conform to existing requirements and other specifications at different architectural levels. In addition, their internal consistency has to be ensured. In this paper, we present an approach to service integration based on a domain-specific language for service choreographies. We first explain the motivation for our work by defining the industrial context that led to the definition of a domain-specific choreography language, called message choreography modeling (MCM). We then provide syntax and semantics for MCM, together with suitable methods for ensuring its consistency. Finally, we report on our experience in applying the described language in practice. [ABSTRACT FROM AUTHOR]

A service choreography is a distributed service composition in which services interact without a centralized control. Adequate adaptation strategies are required to face complex and ever-changing business processes, given the collaborative nature of choreographies. Choreographies should also be able to adapt to changes in its non-functional requirements, such as response time, and especially for large-scale choreographies, adaptation strategies need to be automated and scale well. However, the body of knowledge regarding choreography adaptation approaches has not yet been consolidated and systematically evaluated. By means of a systematic literature review, in which we examined seven scientific paper sources, we identified and analyzed the state-of-the-art in choreography adaptation. We found 24 relevant primary studies and grouped them into six categories: model-based, measurement-based, multi-agent-based, formal method-based, semantic reasoning-based, and proxy layer-based. We analyzed (i) how each strategy deals with different types of requirements, (ii) what their required degree of human intervention is, (iii) how the different studies considered scalability, (iv) what implementations are currently available, and (v) which choreography languages are employed. From the selected studies, we extracted key examples of choreography adaptation usage and analyzed the terminology they adopted with respect to dynamic adaptation. We found out that more attention has been devoted to functional requirements and automated adaptation; only one work performs scalability evaluation; and most studies present some sort of implementation and use a specific choreography notation. [ABSTRACT FROM AUTHOR]

E-commerce collaborations and cross-organizational workflow applications are increasingly attractive given the universal connectivity provided by the Internet. Such applications are inherently concurrent and non-deterministic, so standard software engineering practices are inadequate, and we need new techniques to design extended collaborations and ensure that the implemented designs will behave correctly. The emerging technique for achieving this is to use a choreography, a global description of the possible sequencing of message exchange between the participants, as the basis for both the design of the collaboration and verification of its behavior. We describe a new technique that uses compositions of partial descriptions to define a choreography and show how the technique can be used to model the use of data and computation in the rules of the collaboration. We define conditions for correctness and show that they can be applied separately to each partial description. We demonstrate the expressive power of the technique with examples and discuss how it improves on previously published approaches. [ABSTRACT FROM AUTHOR]