The Internet of Things (IoT) paradigm is based on intelligent
and self configuring nodes (things) interconnected
in a dynamic and global network infrastructure. It represents
one of the most disruptive technologies, enabling ubiquitous
and pervasive computing scenarios. IoT is generally characterized
by real world and small things with limited storage
and processing capacity, and consequential issues regarding
reliability, performance, security, and privacy. On the other
hand, Cloud computing has virtually unlimited capabilities in
terms of storage and processing power, is a much more mature
technology, and has most of the IoT issues at least partially
solved. Thus, a novel IT paradigm in which Cloud and IoT are
two complementary technologies merged together is expected
to disrupt both current and future Internet [59], [23]. We call
this new paradigm CloudIoT. This paper reviews the literature
about the integration of Cloud and IoT a really promising
topic for both research and industry. We have reviewed the
rich and articulate state of the art in this field by considering
a large number of papers proposing an integrated usage of
Cloud and IoT, and published between 2008 and 2013 in
different, selected venues. As shown in Fig. 1, both topics
gained popularity in the last few years (Fig. 1a), and the
number of papers dealing with Cloud and IoT separately shows
an increasing trend since 2008 (Fig. 1b)1. On the other hand,
a more recent and rapidly increasing trend deals with Cloud
and IoT together. Following the indications reported in [40],
we adopt the research methodology schematically depicted in
Fig. 2. We first provide a temporal characterization of the
literature aiming at showing in a qualitative way the temporal
behavior of the research and the common interest about the
CloudIoT paradigm. Second, we provide a detailed discussion
on the CloudIoT paradigm, highlighting the complementarity
and the need for their integration. Third, we detail the new
application scenarios stemming from the adoption of the
CloudIoT paradigm. Fourth, jointly analyzing the CloudIoT
paradigm and the application scenarios, we derive the hot
topics and related issues for research. Fifth, we describe
the main platforms (both commercial and open source) and
research projects in the field of CloudIoT. Finally, thanks to
the previous seven steps, we derive the open issues and future
directions in the field of CloudIoT.