Exercise: Weather Forecast Messaging System (WFoMS)

WFoMS is a weather service which has a network of internet connected weather sensors all over the world. All of these sensors maintain a connection to a broker and every ten minutes, they report the current temperature. A node connected to the broker either publish or subscribe to particular topics which are somewhat like message subjects. The broker to decide who will receive a message. Basically, system are arranged around the managed message broker, WFoMS IoT Hub, in a star topology. This is a very different model to the standard client/server approach, but the decoupling it provides is a huge advantage in many situations.

The IoT Hub uses the MQTT protocol, an open, lightweight, simple, and easy-to-implement messaging transport protocol. Topics in MQTT have a particular syntax. They are arranged in a hierarchy using the slash character (/) as a separator, much like the path in a URL.

A weather station publish to a particular topic based on their location in the following format: sensors/{type}/{country}/{state}/{location},

so an example of a location Kajang, Selangor Malaysia (weather station code: MYXX0005)would publish to with a message containing the current temperature as follows: sensors/temperature/my/selangor/kajang

Other example of weather stations include, Klang (MYXX0006), Ipoh (MYXX0003) and others.

Three nodes are subscribe to the IoT Hub: a Database (to keep a history of the weather data), a Live Display and Weather Radar. The Database keep an up to date database of historical temperatures so it creates a database service which can subscribe to an MQTT topic, # . The database service will then be notified when a new temperature is received. The Live Display provide a real-time interactive dashboard of weather information. For example, the Live Display subscribe to a topic, sensors/temperature/my/selangor/+, to receive the temperature forecast for all cities in a Selangor. While, Weather Radar is a weather surveillance radar that analyse weather data to determine its potential to severe weathers such as storms, typhoon etc. For example, the Weather Data subscribe to topics

such as sensors/precipitation/my/selangor/klang, sensors/wind/my/selangor/klangand

sensors/temperature/my/selangor/klang to receive the precipitation, wind and temperature forecast of Klang.

a) Identify architectural style described in the scenario. [2M]

b) Draw a conceptual diagram of the WFoMS architecture based on the adopted architectural style. [18M]