We had to develop a service oriented architecture with the following goals:

• Send metrics with an Arduino board with an IoT communication protocol (MQTT) to a message broker (emqx)
• Receive sensors metrics and do some aggregations
• Do an admin GUI for managing the customers devices
• Develop a mobile app for displaying the metrics, devices, aggregations based on filters to the customers
• Use OAuth2 authentication (Azure AD B2C)

• Use .NET or Java for some services and use relational databases
• Develop our own "aggregation engine" instead of using technologies like Spark Streaming

• Improve the code quality, we didn't have a lot of time
• Add testing