© Adeel Javed 2016 139
A. Javed, Building Arduino Projects for the Internet of Things,
DOI 10.1007/978-1-4842-1940-9_7
CHAPTER 7
IoT Patterns:
On-Demand Clients
Compared to realtime IoT patterns that provide end users with data instantaneously,
on-demand patterns provide end users with data only when it’s requested. IoT
applications built using this pattern get information by directly accessing the device
or by getting it from a pre-stored location. On-demand patterns are useful when your
application is not actively looking for data and only accesses it when needed.
In this chapter, you are going to build an example of this pattern, called a smarter
parking system. Figure 7-1 shows a high-level diagram of all components involved in
building this system. The first component is an Arduino device that monitors the status
of parking spots with a proximity sensor and publishes it to a server using an HTTP
request. The second component is a server with services to store parking spot data and an
interface service that provides the number of open parking spots. The final component is
an iOS app that accesses open parking spot data and displays it to users when requested.
Figure 7-1. Components of the smarter parking system