Choreography in the embedded systems domain: A systematic literature review <s> Comparison of study frequencies <s> Intelligent systems, composed by devices with embedded computing capability, sensors and actuators interacting with the environment, will enhance and support manufacturing in the future. SOCRADES (Service-oriented cross-layer infrastructure for distributed smart embedded devices) is a European research project that focuses on the development of a platform for next-generation industrial intelligent systems, exploiting SOA paradigm. Within SOCRADES a Technology Roadmap is being developed. Its aim is to provide inputs for the orientation of technological research to achieve the long term objectives required for the enhanced and pervasive exploitation of intelligent systems for manufacturing support. We present the Expected Features of Technology Areas (EFTAs) identified within SOCRADES Technology Roadmap. Then we show how the outcome of SOCRADES Technology Roadmap addresses important needs such as those pointed out by the Strategic Research Agenda developed by ARTEMIS (European Technology Platform for Embedded systems). <s> BIB001 </s> Choreography in the embedded systems domain: A systematic literature review <s> Comparison of study frequencies <s> The development of embedded networks poses several challenges: complexity and size of the network, heterogeneity of nodes, and infrastructure dynamics. From other IT domains it is known that many of these challenges can be met by a Service Oriented Architecture (SOA). In the context of embedded networks, an application can be interpreted as a set of interacting services that produce, consume or manipulate data. However, the hard boundary conditions of embedded networks, such as limited resources and real time requirements, have to be taken into account. This paper discusses an embedded SOA (∈SOA) concept based on the definition of an embedded service (∈Service) term and the differences to traditional Web services based SOAs. The paper describes a middleware platform that supports the execution and development of embedded network applications by employing model based code generation and a pattern based service composition model. The advantages of the approach are showcased using an application from the building automation sector, focusing on the energy management of smart buildings. <s> BIB002 </s> Choreography in the embedded systems domain: A systematic literature review <s> Comparison of study frequencies <s> 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. <s> BIB003
Leite et al. BIB003 characterised the choreography adaption strategies without considering the domain of application and for this purpose defined the analytical tool. This tool was used in this study to characterise the adoption strategies in the ES domain. The results from the comparison of the study frequencies in Leite et al.'s study and the frequencies from this analysis are presented in The frequency comparison of the target indicates that in the ES domain, more effort is made to investigate the adaption of non-functional requirements. Compared with Leite et al.'s BIB003 findings, the number of studies that investigate the non-functional requirements are 16% higher in this study. The stronger emphasis on non-functional requirements can be explained by the specific constraints that exist in the ES development domain and impose stronger consideration of non-functional requirements. Examples of these constraints are discussed in BIB002 , BIB001 and include limitations in processing power, storage and power supply, the demands for reliability, scalability, maintainability, real-time processing and execution in ad-hoc network environments. A human intervention degree analysis reveals that the strategies with the hybrid intervention degree are the dominant strategies in the ES domain (14, 49%), which differs from Leite et al.'s BIB003 study in which automated intervention strategies is dominant (16, 67%) . Lower utilisation of automated techniques in ES can be explained by the relatively short (10-year) time span of choreography usage in the ES domain. During this time, the automation techniques used for choreography adaption could not reach higher degrees of maturity. The analysis of the future trends presented in Section 4.1.2 shows that 7 studies plan to continue their research by automating their current proposals. This indicates that more studies focusing on automation can be expected in near future. Scalability is the aspect of choreography adaption that has not yet been studied sufficiently in the ES domain; it is only considered in 3 studies, or 10% of all analysed studies. These results are similar to those of Leite et al. BIB003 in which 4 studies, or 16%, discuss scalability. Accordingly, a conclusion similar to that of Leite et al. BIB003 can be drawn, suggesting that exploring the impact of the choreography adaption strategy on scalability represents an attractive research topic. This is particularly interesting in the ES domain due to rapid increase of their size. In terms of implementation, a significant number of the studies (58% and 69%) analysed in both SLRs include some type of implementation, such as tools, translators or code generators. Based on these frequencies, the same explanation proposed in this study can be proposed for studies analysed by Leite et al. BIB003 . This suggests that the studies are design-oriented and strongly focused on solving practical problems using various implementations. The analysis of the underlying models and languages revealed that standardised models, such as BPMN, WS-CDL like, UML, process algebra and automata, are similarly used in studies analysed in both SLRs (40% and 28%) and that the utilisation of other, custom-made or non-standardised, models is represented more in studies analysed in this SLR (12% and 41%). Standardised models, such as BPMN and WS-CDL, are designed with enterprise system development in mind. One potential explanation for similar percentages of standardised models in both SLRs is that the majority of the studies in Leite et al. BIB003 focus on enterprise systems development, while in the ES domain a number of studies addressed their problems by transferring and using models from the enterprise domain. In both cases, the selection of the standardised languages represents a logical choice. Custom or non-standard models are more often represented in this SLR. One potential explanation for this is partially aligned with the problem that motivated this review, which is the insufficient expressiveness of existing models to capture the complexities that are typical in the ES domain. Accordingly, new languages or customisation of existing languages are being developed to address this problem in the ES domain.