In an interesting development, Red Hat has open sourced its Simple Protocol for Independent Computing Environment (SPICE) virtual desktop protocol. SPICE was originally developed by Qumranet, the company Red Hat acquired in 2008.

http://www.brianmadden.com/blogs/brianmadden/archive/2009/12/10/red-hat-makes-the-qumranet-spice-protocol-open-source-a-free-alternative-to-ica-pcoip.aspx

SPICE, PC-over-IP (PCoIP) and Independent Computing Architecture (ICA) are all basically advances/alternatives to the RDP (Remote Desktop Protocol). But the disadvantage with RDP was that it always needed a client app, and so a client OS. This has, however, changed with the next wave of products, VMware/Traduce, Microsoft/Celesta and Red hat/SPICE, which neither require a client OS nor a special app (just a monitor with a special card). So effectively the client has become a silent terminal with a host OS.

http://www.teradici.com/pcoip/pcoip-products/add-on-products.php

SPICE enables Virtual Machines (VM’s) to act as a host OS for remote desktops. This truly actualizes the world of “cloud computing” i.e. a single server hosting a number of VMs with remote desktop capability. Here’s the architecture:

http://architects.dzone.com/news/red-hat-says-spice-must-flow
http://www.redhat.com/about/news/prarchive/2009/spice-os.html

The following link takes us back 20 years to the beginning of the client/server era as IBM has just announced mainframes which can run 64 instances of Linux.

http://www.theregister.co.uk/2009/12/11/ibm_linux_only_mainframe/

So imagine using a monitor and being able to switch between different VM’s on different backends (backend could be a mainframe or a cluster or just a basic server).