Connection between client, connection server and VDI

I will like to know as how the VDI connection works. below scenario:

Conection server is in domain xyz.
VDI is created in domain pqr.

1. While trying from client machine to access the connection server then VDI using horizon view client(PCoIP/ Microsoft RDP) how will be connecion be established from start the point we connected the connection server--which protocol and which port?

How is connection between client--->connection server--->VDI (accessed using PCoIP)

How is connection between client--->connection server--->VDI (accessed using Microsoft RDP)

2. While trying from client machine to access the connection server then VDI using html web access how will be connecion be established from start the point we connected the connection server--which protocol and which port?

How is connection between client--->connection server--->VDI (accessed using PCoIP)

How is connection between client--->connection server--->VDI (accessed using Microsoft RDP)

Pls suggest.

It will be great help

Thanks in advance.