Alberto Pan

The Internet of Things (IoT) makes it possible to connect objects or things to the internet, with the purpose of collecting data and controlling processes or machines remotely. IoT enables the physical world to be integrated into the digital world in order to optimize time, save costs and facilitate human labor. An IoT system comprises a rich ecosystem of elements that make up its value chain, which includes a computational and communication architecture or model, components and technologies. IoT has evolved rapidly, producing an exuberant scientific literature. This document presents the state of the art of IoT, with updated sources, that guides the reader, who is entering the world of IoT, to have a starting point for future research. In addition to the review of IoT architectures, components of the IoT ecosystem, computational paradigms and, security and governance aspects. Our main contribution is focused on the analysis of the Middleware layer in IoT architectures, oriented to the storage and processing of data.

Portlets are interactive Web mini-applications that can be plugged into a portal. This chapter focuses on “portletizing” existing Web applications, that is, wrapping them as portlets, without requiring any modification. After providing some background on portlet technology, we discuss two kinds of approaches to portletization: automatic and annotation-based. Automatic approaches make use of heuristics to automatically choose the fragments of the Web application pages to be displayed into the space available in the portlet’s window. In turn, in annotation-based approaches, it is the portal administrator who annotates each page of the portletized Web application to specify which fragments should be displayed. Annotation-based approaches also allow to supplement the functionality of the original Web application. Each approach is explained by using a sample scenario based on the same Web application. We also pinpoint the advantages and shortcomings of each approach, and outline future trends in portletization.