New to Appium. Some general questions

Hey there,

i am new to Appium and would like to know a few things about it.

As far as i understand the concept of Appium correct its acting as a own Rest API between the client and application logic executed on a mobile device.

So would it be possible to create my own Rest API out of it to achieve a use case like the following

http://domain.com/api/get_messages1 (To execute specific code on the mobile device. For e.g to retrieve a list of messages received in some app)

http://domain.com/api/send_message (To execute specific code to send a message inside the app on the mobile device)

And secondly is it possible to execute some specific call simultaneously on the same device without having to wait until the first action completed?

thanks in advance for your help