What must the back-end app prepare for invoking a direct method?

Invoking a direct method on a device in IoT is a way for back-end applications to communicate with and control the device directly. For this process to be successful, the back-end app needs to prepare specific parameters and timeout specifications that will be sent to the device with the method call.

Parameters are essential because they allow the back-end application to pass any necessary arguments or data that the method requires for execution. Timeout specifications are equally important, as they define how long the back-end application should wait for a response from the device before considering the invocation unsuccessful. This ensures that the communication is efficient and allows the application to handle scenarios where the device may be unresponsive or taking too long to process the method call.

In contrast, the other options do not directly relate to the requirements for method invocation. Firmware updates are about updating the device's software and are not needed for method invocation. Access tokens, while necessary for authentication and security, are not specifically part of the method invocation preparation but are typically handled separately as part of the overall security context. Lastly, data storage locations in the cloud pertain to where data is stored or processed, which is unrelated to the direct method invocation process itself. Thus, preparing parameters and timeout specifications is critical for ensuring the successful