How to make two web apps (or app services) talk over a vnet?

HI 

I'd like to get some information to see if what I'm trying to do is possible.  I have the following scenario:

An Azure Web App called WebApp1

Another Azure Web App called WebApp2

An Azure VNet which both web apps are connected to.

WebApp1 talks to WebApp2 via a REST API.   I'd like WebApp1 to be able to talk to WebApp2 over the vnet to hopefully reduce latency and be more secure e.g. not going out over the public web.

My question is how does WebApp1 address WebApp2 when making an http request in this scenario?  For WebApp2 I only have the public IP address and the external dns name (e.g. *.azurewebsites.net ) which I assume will still go over the public web.

I could convert WebApp2 to a WebRole but I like the App Services due to git deployments, slot settings and faster deployments so I'd rather stick with them.

Is it possible to do what I'm trying to achieve?

Thanks

Jamie