OpenIoT: Open Source Internet-of-Things in the Cloud - Interoperability and Open-Source Solutions for the Internet of Things - page 13

1 Introduction

We are nowadays witnessing the convergence of the Internet-of-Things (IoT) and the
cloud computing paradigms, which is largely motivated by the need of IoT applications
to leverage the scalability, performance and pay-as-you-go capabilities of the cloud.
During recent years several efforts towards IoT/cloud convergence have been undertaken
both in the research community (e.g., [ 1 ]) and in the enterprise (e.g., Xively.com).
A common characteristic of these efforts is their ability to stream data to the cloud in a
scalable and high performance way, while at the same time providing the means for
managing applications and data streams. Nevertheless, these architectures do not
essentially provide semantic interoperability [ 2 ] across IoT applications which have been
developed/deployed independently from each other. Therefore, there is still no easy way
to combine data streams and services from diverse IoT applications that feature incom-
patible semantics (e.g., units of measurement, raw sensor values and points of interest).
This paper presents an overview of the FP7-287305 OpenIoT project (co-funded by
the European Commission), which has provided a middleware platform enabling
the semantic uni cation of diverse IoT applications in the cloud. OpenIoT uses the

W3C Semantic Sensor Networks (SSN) ontology [ 3 ] as a common standards-based
model for semantic uni cation of diverse IoT systems. OpenIoT offers a versatile

infrastructure for collecting and semantically annotating data from virtually any sensor
available. OpenIoT exploits also the Linked Data concept [ 4 ] towards linking related
sensor data sets. Furthermore, OpenIoT provides functionalities for dynamically

l-
tering and selecting data streams, as well as for dealing with mobile sensors. It comes
with a wide range of visual tools, which enable the development of cloud based IoT
applications through minimal programming effort.
OpenIoT is currently available as an open source project ( https://github.com/
OpenIotOrg/openiot/ ) . As of June 2014, it consists of nearly 400.000 lines of code,
while it also integrates libraries of the popular Global Sensor Networks (GSN) open
source project [ 5 ]. Recently, OpenIoT received an award from Black Duck, as being
one of the top ten open source project that emerged in 2013 [ 6 ]. The rest of the paper is
devoted to the presentation of the main technical developments of the project. The
structure of the paper is as follows: Sect. 2 provides an overview of the OpenIoT
platform, including an illustration of its architecture. Section 3 is devoted to the pre-
sentation of the main functionalities of the platform and how they can be used towards
developing IoT applications. Section 4 provides an overview of real-life IoT applica-
tions, which have been developed based on OpenIoT. Section 5 concludes the paper.

2 OpenIoT Platform Overview

2.1 Achitecture Overview

The OpenIoT architecture comprises seven main elements [ 7 ] as depicted in Fig. 1 .

￿ The Sensor Middleware (Extended Global Sensor Networks, X-GSN) collects,

lters and combines data streams from virtual sensors or physical devices. The
Sensor Middleware is deployed on the basis of one or more distributed instances