Samer El-Haj-Mahmoud of HP posted a message to the EFI development list, with an update on iPXE, supporting UEFI HTTP Boot:
It looks like iPXE has been updated to work with UEFI 2.5 HTTP Boot, and tested with OVMF. Their page also includes instructions for configuring the DHCP server to enable HTTP Boot, and building OVMF with HTTP_BOOT enabled. It would be interesting to see if iPXE EFI version will directly use EFI_HTTP_PROTOCOL or carry its own TCP/IP HTTP code.
Excerpt from iPXE site:
Version 2.5 of the UEFI specification introduces the UEFI HTTP Boot feature. You can use the basic UEFI HTTP Boot client to chainload iPXE from an HTTP server, eliminating the need for a separate TFTP server in your boot infrastructure. The simple UEFI HTTP Boot client will download and boot iPXE. You can then use any of iPXE’s more advanced features such as HTTPS, Digest authentication, POST requests, scripts, menus, customisable code signing etc. to download and boot your operating system. UEFI HTTP chainloading provides a way to load iPXE on systems which do not have iPXE present as part of the UEFI firmware. If your system already provides iPXE as part of the UEFI firmware, then you do not need to use UEFI HTTP chainloading.
More information:
http://ipxe.org/appnote/uefihttp
http://article.gmane.org/gmane.comp.bios.edk2.devel/2756
Firmware Security 
Why doesn’t the ASUS Z170 motherboard have IPv4/IPv6 HTTP boot support in the UEFI network stack even after the latest BIOS update. There is only support for IPv4/IPv6 PXE boot support in the UEFI network stack. I checked the UEFI version using the ver command in the UEFI shell from shell.efi and it’s UEFI 2.50.
LikeLike