A Visual Paradigm for IoT Solutions Development - Interoperability and Open-Source Solutions for the Internet of Things - page 26

eases the development and deployment of EPCglobal compliant RFID applications,
while the Linked Sensor Middleware (LSM) platform (Lephuoc 2011 ) facilitates the
integration of applications that leverage the Semantic Sensor Networks (SSN) (Compton
2012 ) ontology towards modeling ICOs. Apart from middleware platforms that support
standards-based development of IoT applications, there are also several platforms that
provide proprietary middleware services to IoT applications. Prominent examples
including the Global Sensor Networks (GSN) open source middleware (Aberer 2007 )
for WSN, as well as the WinRFID platform for RFID applications (Prabhu 2006 ).
In addition to these examples, numerous methodologies and platforms for building
multi-sensor IoT applications have been also introduced (Chatzigiannakis 2007 ).
Despite the emergence of the above platforms, less emphasis has been paid into the
provision of easy to use tools for the development of IoT applications. Indeed, most of
the above-listed platforms are not accompanied by comprehensive development
environments that could essentially facilitate developers and solution providers in the
complex task of building, testing and deploying IoT applications. In several cases the
above-listed platforms come with simple tools for con guring solutions, which are not

however integrated and do not support all the phases of the software development
lifecycle. Also, with only few exceptions (e.g., (Patel 2011 )), these tools are con-
strained to particular types of applications (e.g., RFID or WSN applications) and
cannot support the full range of physical and visual ICOs that comprise the IoT par-
adigm. Hence, they are not suitable for supporting an integrated development envi-
ronment for IoT applications based on Model-Driven-Architecture (MDA) concepts
(Kleppe 2003 ). Furthermore, most of the available tools provide poor congurability
and require application developers to write signi cant amounts of code even for simple

solutions. We strongly believe that visual integrated tools for IoT development can
greatly facilitate the production of IoT applications, thereby reducing their develop-
ment and deployment costs. Furthermore, such tools could boost the proliferation of the
currently rising community of IoT developers.
In this paper we introduce a range of tools for the visual development of IoT
applications and services, as well as for the visual presentation of their results. These
tools can serve as a basis for an integrated development environment, which could
support the round-trip engineering of IoT applications across all the phases of their
software engineering lifecycle. The presented environment relies on a blueprint cloud-
based IoT architecture, which leverages the W3C SSN ontology for modeling sensors,
ICOs and entities. This architecture is briefly presented and discussed in the paper, in
order to facilitate the understanding of the middleware platform that underpins the
introduced visual environments. Due to the use of W3C SSN as an underlying model
for sensors and ICOs, the presented tools are used to construct semantic queries/
services (i.e. SPARQL based queries) over the various sensors and ICOs. Furthermore,
they provide the means for validating the services, as well as for enacting them over the
underlying IoT middleware platform. Overall the presented tools provide a

rst-of-a-
kind effort towards the integrated standards-based (i.e. W3C SSN based) development
of IoT applications with minimal (and in some cases zero) programming. In this
context, the work described in the paper complements recent efforts for integrated IoT
development (e.g., (Patel 2013 )), which are however based on proprietary ontologies
for modeling sensors and IoT resources. It is also noteworthy that our visual