Building a battery-powered IOT device is a very interesting challenge. Advancements in technology have enabled IOT module chips to perform more functions than ever before. There are chipsets available today that are smaller than a penny in size, yet they are equipped with GPS, Wi-Fi, cellular connectivity, and application processing capabilities. With these developments, it is an opportune time for the creation of small form factor IoT devices that can connect to the cloud and solve interesting problems in all domains.
There are plenty of applications where the IOT device needs to be accessed externally by an application to request a specific task to be executed. Think of a smart home lock device that needs to open and close the door lock from a mobile application. Or an asset tracking device that must start logging its location upon request. The basic idea is to be able to issue a command to these devices and make them perform an action.