Wednesday, September 15, 2010

XAuth!

Meebo and some other supporters just released XAuth. The video on page http://xauth.org/info/ is really informative. XAuth provides front-end solution for registration of various web service sessions.

  • If you are authenticated to a service, the service puts a registry entry into XAuth local storage.
  • Other mashup apps/publisher websites can ask XAuth for a list of web services that the user has been authenticated to. Then the app can adjust UI according to the retrieved data.

In current reference implementation, it requires HTML5 features – postMessage and local storage.

Javascript code: http://github.com/xauth/xauth
Official web site: http://xauth.org/

Sunday, September 12, 2010

Numbers Everyone Should Know

LADIS2009 keynote slides: http://www.cs.cornell.edu/projects/ladis2009/talks/dean-keynote-ladis2009.pdf

Following numbers are excerpted from the above slides.

L1 cache reference  0.5 ns 
Branch mispredict  5 ns 
L2 cache reference  7 ns 
Mutex lock/unlock  25 ns 
Main memory reference  100 ns 
Compress 1K bytes with Zippy  3,000 ns 
Send 2K bytes over 1 Gbps network  20,000 ns 
Read 1 MB sequentially from memory  250,000 ns 
Round trip within same datacenter  500,000 ns 
Disk seek  10,000,000 ns 
Read 1 MB sequentially from disk  20,000,000 ns