1. The client code establishes a session connection with the Appium server through the http protocol and transmits caps configuration information
2. Appium server checks whether the configuration information meets the requirements
3. UI automator and adb are provided by the SDK
(UI automator is used for element positioning, and adb is the Android debugging bridge for connecting devices)
4. Use the adb tool to check the currently connected mobile device
5. When the script is run for the first time, appium-settings and uiautomator2 will be installed on the tested phone
6. The phone starts appium-settings as a monitoring service to communicate with appium-server
7. uiautomator2 starts the app under test (the code specifies that the underlying driver is UI2)