what is purpose of REST in web services and how will be able to use in iot projects with bolt devices
You can read about REST API and its usage using below link.
You will be using our remote API’s to control the pins on the Bolt device as well as reading the inputs from the various sensors.
Representational State Transfer ( REST ) is an architectural style that specifies constraints, such as the uniform interface, that if applied to a web service induce desirable properties, such as performance, scalability, and modifiability, that enable services to work best on the Web.
If I disconnect my bolt device from the cloud then can I run all program of API key? Like control LED using BOLT with API key
APIs get connected to the cloud, and if the cloud is connected to your device, it is possible to control the device through API. But when the device is disconnected from the cloud, you can only try to manipulate the data on the cloud through the API but can not control the device. The connection is set between the cloud and the API and not between API and the device. Once disconnected from cloud, the device also gets disconnected from the API.
So, you can’t control your LED using Bolt with API key when your device is offline.
@Harsh In order to run the commands, it is necessary to connect the device to the cloud and so if you have to control the LED, you must connect the BOLT device with the cloud.