Arduino on - Internet connected applications

I'd like to be able to create an Internet connected application using Arduino on LP. I'm very familiar with using Arduino and using various WiFi shields to build (for example) MQTT or HTTP applications on an Arduino. In the Arduino world you need a "client" (something that gives you access to the "socket") and then you could use an MQTT library or HTTP library to do the rest of the stuff.

My LP is connected to the Internet (via WiFi). But I can't figure out how, from within an Arduino sketch, I can get access to the "client" or a bridge of sorts.