# RPC

### Introduction

This sample shows the data exchange between the frontend and backend of a device. After the offering and quantity are selected at the frontend, the backend calculates the result and displays it at the frontend.

### Usage

1. Touch the blank box of an offering type. The offering selection list is displayed. Select an offering. The corresponding content is displayed in the blank box.
2. Touch **+** or **-** next to the offering selection box and select the quantity of the offering.
3. Touch **Confirm an order**. The total price is displayed.

### Constraints

This sample can only be run on standard-system devices.