From the perspective of a computer scientist, a city is also an information-processing entity. And so when IT talks about “smart cities” they usually talk about a system of many data sources and actuators distributed in the city, and the infrastructure to use them meaningfully.
Data sources are things like a sensor temperature sensor, or a bus which reports that it arrives at a certain bus stop. And last but not least the smartphones of citizens can also be viewed as data sources.
Actuators can be something like a street lamp, which can be switched on and off.
The information can also leave the infrastructure: independent parties can develop, for example, service apps to access the data. If the data is published without any special restrictions one speaks of open data.
A simple application of this IT-smart-city concept is the use of traffic flow-based traffic light controllers. Such solutions are in use since decades, longer than the term “Smart City” exists.
A recent example was realized in the Spanish city of Malaga. Objective is the more effective combating of vermin. Messages of infestation are combined with data from the environmental sensors. The systems searches for correlations. The system then uses also data from the weather forecast to calculate the probability of occurrence of vermin infestations in a certain district. This helps the city authorities to take measures more purposeful and efficiently.
European smart-city infrastructure
As application developers, it is illusory to address each sensors of an entire city individually. A central authority is desirable, that collects data from the sensors, puts them in relationship, and aggregates. Because sensors provide data about their respective environment, such a central instance is called also a context broker.
The European project FIWARE has developed (among other things) such a context broker and supporting IT-infrastructure. In this system all data can be accessed using standard interfaces (NSGI9 and NSGI10 of the Open Mobile Alliance)
The cities get the chance to implement a proven solution. As an application developer, you have the chance to write solutions that work for several cities.
The infrastructure was first used in some Spanish cities. The above example from Malaga has been realized with this infrastructure.