Towards a Platform for Urban Data Management, Integration and
Processing
Elarbi Badidi
1
and Muthucumaru Maheswaran
2
1
College of Information Technology, United Arab Emirates University, Al-ain, United Arab Emirates
2
School of Computer Science, McGill University, Montreal, Canada
Keywords: Smart City, Iot, Urban Data Streams, Semantic Interoperability, Edge Computing, Urban Data Analytics.
Abstract: Smart city infrastructure includes deployment of a variety of sensors and provision of open data platforms
and applications that can help improve the quality of life of the citizens. The large volumes of data
generated by sensors and various Internet of Things (IoT) devices need to be harnessed to help smart city
applications make informed decisions on the fly. Also, efficient management of smart city components
relies on the ability to federate their data, locally process urban data streams, and utilize big data analytics to
harness their governance. Data interoperability and integration is one of the most challenging problems
facing smart cities today. Successful data integration is one of the keys to improved services and
governance. This paper describes the architectural design of a framework that aims to deal with the
integration of data across the various systems of the city, urban data analytics, and creation of value-added
services. The framework relies on recent technologies for data processing including IoT, edge computing,
cloud computing, data analytics, and semantic integration.
1 INTRODUCTION
Over the last few decades, cities are experiencing
tremendous pressure due to migration waves and
urban growth. Their infrastructures need to cope
with growing demand for the supply of energy,
water, transportation, and healthcare services. City
stakeholders are using digital technologies to reduce
costs, improve the quality of services delivered to
citizens, balance budgets, and enhance the efficiency
of various city systems. However, the lack of
integration of data generated by the diverse city
components and systems results in making city
utilities and services operate sub-optimally, limiting
the creation of value-added services, increasing
transport costs, etc. Recent digital technologies offer
new opportunities to mitigate these impacts and
transform cities into smart cities through smart and
innovative planning, management, and operation.
Managing a smart city holistically and
harnessing its governance are becoming essential to
federate its data, locally process data streams
generated by various IoT devices and sensors, and
utilize big data analytics (Khan, 2015) (Ojo, 2015).
An integrated data perspective can benefit smart
cities using big data collection, integration,
processing, and sharing through cloud-based
services. Nevertheless, such data integration and
utilization necessitate suitable software technologies
to collect, store, analyze and visualize enormous
amounts of data from the city ecosystem.
Data interoperability and integration are two of
the most challenging issues facing smart cities today
(Trilles, 2016) (Gyrard, 2016). Indeed, to enable the
efficient governance of smart cities and to create
value-added services that enhance the lives of
citizens, smart city stakeholders have to interpret
many types of information from a variety of sources
including water consumption, road traffic, energy
consumption, healthcare services, and many others.
Unfortunately, they are not currently able to
efficiently harness that information because of the
massive amounts of generated data, data
heterogeneity across the city systems, and the lack of
a common data model and ontology. Successful data
integration is one of the keys to improved services
and governance (An, 2016) (Luciano, 2014). It will
allow for analyses of economic activity, resource
consumption, mobility patterns, and public health,
which will guide the city development.
This work describes the architectural design of a
framework able to deal with the integration of data
Badidi, E. and Maheswaran, M.
Towards a Platform for Urban Data Management, Integration and Processing.
DOI: 10.5220/0006789602990306
In Proceedings of the 3rd International Conference on Internet of Things, Big Data and Security (IoTBDS 2018), pages 299-306
ISBN: 978-989-758-296-7
Copyright
c
2019 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
299
across the various systems of the city, urban data
analytics, and creation of value-added services. The
framework relies on recent technologies for data
processing including IoT, edge computing, cloud
computing, data analytics, and semantic integration.
The framework aims at allowing smart city
stakeholders to connect, manage, process and
analyze data from thousands of IoT devices and
sensors at the edge of their networks. It will mainly
allow to:
collect data from thousands of IoT devices,
normalize the integration of IoT devices within
the smart city,
perform real-time big data analytics on IoT
streams and events, and
extend smart city applications and processes
with IoT data seamlessly.
The remainder of this paper is organized as
follows. Section 2 provides background information
on urban data streams and describes the challenges
of urban data streams processing. Section 3 provides
an overview of some of the techniques used for data
integration. Section 4 describes the conceptual
architecture of our proposed framework for urban
data integration. Section 5 discusses challenges and
concerns of urban data integration. Finally, Section 6
concludes the paper.
2 URBAN DATA STREAMS
In a smart city context, systems are equipped to
work with real-time data from sensors, electric and
water meters, or other devices used to assure the
functions of the city. Sensors usually convey
information about real-world phenomena, generally
ranging from direct measurements such as
temperature or pressure to user observations like
water leaking. Sensors include not only hardware
sensors but also people. The concept of people as
sensors refers to users providing direct input via
social networks or dedicated end-user interfaces
(Doran, 2013).
Urban data streams come from a variety of IoT
devices and sensors that monitor and report on:
Weather conditions as they relate to traffic
jams and accidents so that alerts and warning
systems are activated.
Parking space availability so that drivers avoid
the lengthy searches for open spaces.
The structural integrity of bridges, historical
monuments, and buildings when it comes to
the impact that weather conditions and
vibrations have on the structure’s safety.
Trash levels in waste containers to optimize
trash collection routes.
Night activity and traffic so that adaptive smart
lighting lights streets, sidewalks, and roads in
an energy efficient manner.
Over the last few years, the European Union has
been encouraging its member states to develop smart
cities and allocated 365 million euros for this
initiative. Amsterdam, Barcelona, and many other
cities are leading the smart city development effort.
Copenhagen, which aims to be the world’s best
city for cyclists, has started monitoring the city's
bike traffic in real time by deploying sensors
throughout several parts of the city. These sensors
provide valuable data helping improve bike routes in
the city as at least 50% of the city's residents
commute to their workplaces or educational
institutions by bike every day (Wired.com, 2015).
London started installing smart parking sensors
that would allow drivers using a map to view a real-
time map of parking spaces and to quickly locate
parking spaces and remove the need for lengthy
searches for an open spot. Londoners hope that this
system would alleviate urban traffic congestion and
cut down on carbon emissions. Other cities around
the world are also trying out deploying smart
parking systems in an attempt to improve the
everyday life of their citizens (Computing, 2014).
Furthermore, many cities are using cutting-edge
IoT solutions to implement intelligent adaptive street
lighting systems. These systems can help cities
create safer urban environments and at the same
time save energy and protect the environment. They
light up when human activity is detected and dim
down to reduce costs when streets are empty. For
example, San Diego city has recently started a $30
million Smart City IoT platform project in what
represents the world’s massive Smart City IoT
platform deployment. The platform will add nearly
3,200 intelligent IoT nodes to the current street
lighting infrastructure to collect real-time sensor
data across the city (Diginomica.com, 2017). The
collected data can be used to optimize municipal
systems, increase safety, guide fire and police to
accident or emergency scenes as well as develop
smart apps that, can, for instance, direct drivers to
available parking spaces.
Several efforts investigated the realization of
smart cities through the IoT, often considered as the
principal technological enabler. Jin et al. (Jin, 2014)
introduced IoT for smart cities from three different
perspectives: network-centric IoT, cloud-centric IoT,
and data-centric IoT. The data-centric IoT
perspective includes data collection, data processing,
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300
data storage, and data visualization. Zanella et al.
(Zanella, 2014) provided a survey of the enabling
technologies, protocols, and architecture for an
urban IoT, i.e., a communication infrastructure that
aims to provide simple, unified, and cost-effective
access to a variety of public services.
One of the challenging issues of current urban
deployments is the non-interoperability of the
diverse and heterogeneous devices and technologies
used in the city (Trilles, 2016) (Gyrard, 2016). These
devices generate different types of data conveyed to
a control center for storage and processing. Zanella
et al. described the Web-service approach for IoT
service architecture and explained its benefits for
implementing interoperable services. International
standardization bodies such as IETF, ETSI, and
W3C, among others, are also promoting this
approach.
3 DATA INTEGRATION
TECHNIQUES
Efficient utilization of data from disparate sources
requires understanding the database schema of each
data source and devising a translation mechanism to
permit data exchange. The literature on data
integration identifies six main techniques: data
consolidation, data federation, data propagation,
utilization of the Extensible Markup Language
(XML) and the JavaScript Object Notation (JSON)
as standard formats for the exchange and storage of
data, development of controlled vocabularies, and
mashups.
Data consolidation refers to the collection of
data from multiple sources and its integration into a
single persistent data store (see fig. 1). It allows to
cope with data duplication and reduce the costs
associated with the reliance on multiple data
management points and databases. It will enable
organizations to do reporting and efficient data
analysis as in data warehousing. The data store can
act as a data source for downstream applications as
in an operational database system. Since data
originates from multiple data sources, there is
always a delay between the time data is generated or
updated in a data source and the time those changes
appear in the data store. Depending on the
underlying communication infrastructure and the
nature and size of updated data, this delay might
range from a few seconds to several days (Loshin,
2009) (Levin, 2004).
Data federation represents an alternative model
for data storage and usage by organizations. Data
federation technology refers to software resources
that provide users with a single logical view to
present and access data stored throughout one or
more data sources. This technique is also known as
data virtualization technology. When the data
sources are traditional databases, data federation
leverages the native data management and search
capabilities of individual source databases and
creates a single, unified, logical view of the
federated databases (Haas, 2002). Business
applications are presented with a combined data
schema even though the source database schemas
are distributed across many federated databases (see
fig. 2). When a business application issues a request
against this logical view, the data federation engine
retrieves data from the appropriate data source,
adapts it to match the virtual view, and sends the
results to the requesting business application
(Loshin, 2009) (Barnaghi, 2015) (Haas, 2002).
Data propagation denotes the movement of data
from one or multiple data sources to target locations.
Data propagation systems usually push data to target
locations. Most often, they are event-driven, and
data propagation is performed according to
propagation rules (see fig. 3). Data updates in a
source system may be propagated to the target
system synchronously or asynchronously (Loshin,
2009). Propagation ensures the delivery of data to
the target system irrespective of the type of
synchronization used. This data delivery guarantee is
a key distinctive feature of data propagation. For
instance, in data warehouses and operational data
stores based systems, updates involve moving large
volumes of data from one system to another. Data
movement is carried out in batches to avoid
impacting the performance of the operations on the
data warehouse.
XML is a markup language that facilitates
sharing of data across heterogeneous computing
systems (Bertino, 2001). Many databases, software
applications, and tools are XML-compliant. XML
facilitates data integration and application
interoperability by adopting standards for
representing certain types of data.
JSON is an open-standard file format that uses
text to transmit data objects consisting of attribute
value pairs and array data types. It is a language
independent and light-weight data-interchange
format, which is easy for humans to read and write
and easy for machines to generate and parse. JSON
is more and more becoming the preferred format for
data exchange and integration using RESTful Web
services.
Towards a Platform for Urban Data Management, Integration and Processing
301
Figure 1: Consolidation of data from multiple sources.
Figure 2: Federation of Data from Multiple Sources.
Figure 3: Data propagation from data sources to
operational data store.
Controlled vocabularies offer a form of data
integration by enforcing naming conventions for
data elements that ultimately appear in databases.
One example of a controlled vocabulary is an
ontology developed in the context of a smart city
(Nemirovski, 2013). The ontology acts as a mediator
for distinct schemas of individual data sources and
as a reference schema for federated data queries.
Also, researchers at the DISIT Lab at the University
of Florence (http://www.disit.org) have created an
ontology for a smart city, which integrates
regulatory elements, sensors, points of interests,
people, etc. and is used in other smart city projects
(DISIT Lab, 2015).
A Mashup is a technique for building new Web
applications that combine data from multiple sources
to create an integrated experience. Mashup
applications can be constructed using widgets, open
APIs, Web services, and data sources. An example
of mashups developed in the case of smart cities is
FixMyCity (Fraunhofer, 2012), a government
mashup that allows citizens to contact the
appropriate person in a local administration quickly
to report damages in public spaces.
4 ARCHITECTURE OVERVIEW
Figure 4 depicts our proposed architecture to address
the data integration and processing issues in smart
cities.
4.1 Infrastructure Layer
This layer is made up of various smart city data
sources such as smart IoT devices, traditional
databases, Web servers, and edge servers. An IoT
device detects some input from its surrounding
environment and responds to it. The particular input
could be light, motion, speed, vibration, pressure,
water level, heat, or any other environmental
phenomenon. The device reading is then converted
into a human-readable form or sent over a network
to a gateway for further processing. An IoT device,
with typically an IP address, can connect to a
network to exchange data. Smart IoT devices enable
automating operations of a city by collecting data on
various physical assets (equipment, vehicles,
buildings, facilities, etc.) to monitor their behavior
and status, and using collected data to optimize
resources and processes. IoT devices and actuators,
which do not have operating systems, connect to
edge devices or edge gateways using Wi-Fi or
Ethernet connections of a Local Area Network
(LAN) or using Bluetooth, ZigBee, and Ultra-Wide-
band (UWB) of Personal Area Network (PAN).
The realization of smart energy, smart transport,
smart health, smart agriculture, etc. will be permitted
by IoT technologies, which require the deployment
of a vast number of IoT devices and sensors. Web
servers’ logs also represent an essential data source
for the various city systems. Log streaming permits
troubleshooting connectivity problems and
diagnosing the causes of service disruptions. Also,
clickstream analysis can be used to assess the
effectiveness of providing online city services.
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Figure 4: Architecture for Smart City Data Integration.
4.2 Edge Computing Layer
As sensors and IoT smart objects generate massive
amounts of data, traditional data management
systems and practices will no longer be sufficient to
take full advantage of the IoT. The fundamental idea
behind Edge Computing (EC) is to place storage and
computation resources at the network edge, in the
proximity of the data generation location. IDC
predicted that: “By 2019, at least 40% of IoT-created
data will be stored, processed, analyzed, and acted
upon close to, or at the edge of, the network
(IDC.com, 2017). Thus, the processing of urban data
streams can be pushed from the cloud to the edge.
EC reduces traffic bottleneck towards the core
network by processing the data locally and
expediting data streams by using various techniques
(i.e., caching and compression). Besides, it helps to
shorten end-to-end latency, enabling the offload of
heavy computation load from power constrained
user equipment to the edge. This can be very
beneficial when IoT devices are deployed on remote
locations suffering from poor network coverage or
when stakeholders aim to reduce the costs of
expensive cellular connectivity technologies.
Edge devices, which are often battery-powered,
run complete operating systems such as Linux,
Android, or iOS. They process raw data they receive
from IoT devices and sensors, and they send
commands to actuators. They are connected to the
data layer directly or through edge gateways. Edge
gateways also run complete operating systems and
have unrestricted power supply, more CPU power,
memory, and storage. They can aggregate data and
support analytics at the edge of the network, and
they act as intermediaries between the data layer and
the edge devices.
Both edge gateways and devices forward
selected raw or pre-processed IoT datasets to the
data layer services, like storage services, machine
learning or analytics services, and they
symmetrically receive commands from the above
layers, like configurations or data queries.
Centralized databases are indispensable for
carrying out the various operations of the smart city
systems. Nevertheless, as the data incessantly
spreads from sensors and IoT devices at the edge,
central databases only need to cope with data inflow
at a more controlled rate for instance once per
minute. Using edge servers, which typically have
limited computing and storage capacities, permits
conveying data in real-time and receiving
instructions in a timely fashion. Data streams can be
aggregated and merged at the edge and then
transported to the central databases as averages of
sensed data over well-controlled periods of time (see
figure 5). Thus, moving data management partially
from primary databases towards the edge of the
network is crucial for coping with real-time data
feeds.
4.3 Data Layer
This layer is in charge of storing and providing
access to data, obtained from the infrastructure, and
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processing and analyzing data that other layers can
use to generate valuable insights.
4.3.1 Data Storage and Access
The resources across a smart city infrastructure
together with people’s wearable devices and
smartphones incessantly generate vast amounts of
data in structured and unstructured formats. IoT
devices and sensors monitor in real-time the
operations of many city systems such as
transportation, water, and energy systems.
Furthermore, social media networks such as Twitter,
Google+, and Facebook, often considered as social
sensors, represent a new source of real-time data.
The data layer allows city stakeholders to store
and access these large urban datasets using
conventional and modern management tools. Over
the last few years, Data-as-a-Service (DaaS)
emerged as a new delivery model for data storage
and provisioning wherein data are provided on-
demand to the consumer regardless of their
geographic locations (Olson, 2009). This delivery
model relies on the service-oriented architecture
(SOA) and advocates the view that data management
can be done in a centralized place where datasets are
cleansed, aggregated, and enriched to be accessed by
different applications or users irrespective of their
location or network.
4.3.2 Data Aggregation
Data aggregation typically deals with large volumes
of data to reduce the size of raw sensory
measurements (Jugel, 2014). It allows reducing the
communication overhead and helps to perform more
advanced tasks in large-scale systems such as
clustering or event detection. To efficiently access
and use sensory data, semantic representation of the
aggregations and abstractions are crucial to
providing machine interpretable observations for
higher-level interpretations of the real-world context
(Jugel, 2014).
Data aggregation is common in many
applications. For example, in the healthcare industry,
to meticulously analyze the situation of a patient, it
is necessary to aggregate data from various IoT-
based healthcare service providers that collect data
of that patient using multiple sensors. Fig. 5 depicts
the aggregation of data from one or several data
streams.
Figure 5: Aggregation of data from one or multiple data
streams.
4.3.3 Data Semantic Integration and
Interoperability
The IEEE defines interoperability as: "The ability of
two or more systems or components to exchange
information and to use the information that has been
exchanged" (IEEE, 1990).
If two or several systems can communicate and
exchange data, they are demonstrating syntactic
interoperability. Specified communication protocols
and data formats are essential for successful data
exchange. XML or SQL standards provide syntactic
interoperability. Syntactical interoperability is a
requirement for any efforts of additional
interoperability. Beyond the ability of two or several
systems to exchange information, semantic
interoperability means the ability to interpret the
data exchanged meaningfully and accurately to
produce useful results as defined by the end users of
both systems. Semantic interoperability requires that
both sides agree on a mutual information exchange
reference model.
In smart cities, achieving semantic
interoperability is a more critical and difficult task
given the complexity of the city ecosystem
(Ramparany, 2016) (Psyllidis, 2015) where
government entities and private businesses often use
different terminologies. Therefore, a semantic data
model should be developed to standardize terms and
descriptors whose meanings are defined. Concerning
this issue at the sensor level, the W3C incubator
group created the Semantic Sensor Network (SSN)
ontology (Compton, 2012).
4.3.4 Data Processing and Analytics
In addition to providing efficient storage and access
to data, the data layer allows city stakeholders to
efficiently transform, and analyze these vast urban
data streams so that applications of the smart city
can use it to generate valuable insights. The real val-
ue of such integrated data will be gained by acquir-
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304
ing new knowledge through the utilization of data
analytics using a variety of data mining, machine
learning, and statistical methods. A growing set of
reputable open source and commercial solutions is
available for data streams processing. This set in-
cludes: Apache Kafka (http://kafka.apache.org),
Apache Storm (http://storm.apache.org), Apache
Samza (http://samza. apache.org), Google Cloud
Dataflow (https://cloud. google.com/ dataflow), and
Amazon Elastic MapReduce (https://aws.
amazon.com/elasticmapreduce). These solutions
allow processing both streaming and historical data,
which is a vital aspect of current smart cities.
For instance, by using Apache Kafka together
with Apache Storm, Apache HBase and Apache
Spark, real-time (or near real-time) data streams can
be processed efficiently. Deployed as a cluster on
multiple servers, Kafka handles its entire publish
and subscribe messaging system with the help of its
four APIs, namely, producer API, consumer API,
streams API and connector API.
4.4 Application Layer
The application layer provides a comprehensive set
of methodologies and tools for efficient design,
development, distribution, and operation of smart
city applications and services. The Service Oriented
Architecture (SOA) embodied by Web services has
emerged as a fundamental technology for providing
services over the Web. Web services are
interoperable across platforms and neutral to
languages, which makes them suitable for access
from heterogeneous environments. Web services
technology has all the potential to be a significant
component in the integration endeavor because it
provides a higher layer of abstraction that hides
implementation details from applications.
In this work, we consider the service-orientation
as the major design principle for the interoperability
foundation for smart city systems facilitating the
ground for the support of security assurance,
semantic layer, IoT integration, business process
management capabilities, and a multimodal portal
with mobile device support. Service orientation will
be the basis for the development of a Smart City
Service Bus (SCSB). The SCSB will be the
backbone of services from the different government
agencies and private businesses. It will enable
creating new value-added services and deliver
updated information at all times to city stakeholders,
citizens, and businesses.
5 URBAN DATA INTEGRATION
CHALLENGES
Data integration and semantic interoperability
involve continuous change management and a
tedious engineering effort. It is a long-term effort
that requires the organization of processes for
consensus-building and cooperation among all
players involved.
The following factors might impact the success
of the data integration endeavor:
Security and privacy issues (Privacy of
personal data, high cost of security applications
and solutions, threats from hackers and
intruders, etc.)
Resistance to sharing data or lack of interest in
data integration by some city entities.
Lack of alignment of organizational goals and
the high cost of IT professionals skillful in data
integration.
Required effort to coordinate data resources
that have conflicting conceptualizations and
representations, which makes the smart city
data integration endeavor harder.
The lack of standards for data integration.
Standardization would significantly alleviate
the above challenges. Standards take too much
time before being approved and implemented.
As we mentioned earlier, already many smart
city initiatives are underway based on the integration
of data obtained from multiple stakeholders. It
remains to be seen to what extent such efforts can
deliver promised intelligent services.
6 CONCLUSIONS
Creation of value-added services and single-entry
point of services for city citizens involves the
integration of data from several governments and
private entities. IoT technologies, semantic
interoperability, service orientation, edge computing,
and cloud computing will play a primary role in the
achievement of the smart city goals. A clear
understanding of the requirements of citizens and
smart city governance goals could reveal the
integration tasks to undertake by the various city
stakeholders and the challenges that have to be
faced. A conceptual data integrative framework is
here proposed to cope with the heterogeneity of
systems at different levels including data models,
data semantics, service implementation, and
interfaces. Edge computing, semantic
Towards a Platform for Urban Data Management, Integration and Processing
305
interoperability, service orientation, and cloud-based
data analytics are the cornerstones of the proposed
framework.
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