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The Internet of Things (IoT) is a paradigm in which smart objects actively collaborate with other physical and virtual resources available in the Internet. IoT environments are characterized by a high degree of heterogeneity, encompassing devices with different capabilities, functionalities, and network protocols. To address such a heterogeneity, some platforms have been proposed aiming at abstracting away the specificities of such devices and promoting interoperability among them. Nevertheless, the lack of standardization in IoT makes these platforms to often not properly address several important requirements in this context. In this context, reference architectures can define an initial set of building blocks for IoT environments and to provide a solid foundation for leveraging its wide adoption. In this paper, we introduce two recent reference architectures for IoT, namely the IoT Architectural Reference Model and the architecture proposed by WSO2. By analyzing the characteristics of these architectures, we intend to shed light on important issues for future research on reference architectures for IoT.

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The nighttime boundary layer was studied in an urban area surrounded by tropical forest by use of a copter-type unmanned aerial vehicle (UAV) in central Amazonia during the wet season. Fifty-seven vertical profiles of ozone concentration, potential temperature, and specific humidity were collected from surface to 500 m above ground level (a.g.l.) at high vertical and temporal resolutions by use of embedded sensors on the UAV. Abrupt changes in ozone concentration with altitude served as a proxy of nighttime boundary layer (NBL) height for the case of a normal, undisturbed, stratified nighttime atmosphere, corresponding to 40% of the cases. The median height of the boundary layer was 300 m. A turbulent mixing NBL constituted 28% of the profiles, while the median height of the boundary layer was 290 m. The remaining 32% of profiles corresponded to complex atmospheres without clear boundary layer heights. The occurrence of the three different cases correlated well with relative cloud cover. The results show that the standard nighttime model widely implemented in chemical transport models holds just 40% of the time, suggesting new challenges in modeling of regional nighttime chemistry. The boundary layer heights were also somewhat higher than observed previously over forested and pasture areas in Amazonia, indicating the important effect of the urban heat island.

Recent research has recognised the potential of coupling ADLs with underlying runtime environments to support systematic and integrated "specification-todeployment" architectures. However, while some promising results have been obtained, much of this research has not considered the crucial issue of causally-connected dynamic reconfiguration and has considered only domain-specific areas. In this paper we discuss a specification-to-deployment architecture called Plastik that employs an extended generalpurpose ADL and is underpinned by an efficient runtime that is suited both for high-level application development and low-level systems development (e.g. embedded systems). Runtime reconfiguration is supported both at the ADL level and at the runtime level, and both programmed reconfiguration and adhoc reconfiguration are supported. The paper focuses on the mapping of ADL-level specifications to runtime instantiations and on the necessary runtime support for causally-connected dynamic reconfiguration.

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