Monday, November 24, 2008

IGT 2008 next week

The world summit of cloud computing is taking place in Israel next week.
I have big expectations toward this summit as I believe that the future is in the cloud.
This is not an affiliation link :-) you are welcome to register I'd love to see you there!

Sunday, November 23, 2008

Last post Recall or why use HTTP1.1

Today I saw that Ford are recalling 1000 cars due to problems in steering wheel liquid. This makes me feel a bit more comfortable about the need to take back what I said just few days ago :-).
So why do I need to recall the post. Not because SSL connection establishment is not expensive. It is indeed. The issue is that HTTP1.1 (opposed to HTTP1.0)  can pool the connections and reuse them for later requests thus diminishing the effect of HTTPS latency).
So why the Apache web server was not behaving well (and put me into confusion)? Configuration .....
The AWS was configured to use HTTP1.0 for HTTPS connection under Internet explorer.
I did not understand yet why(an issue for a later post)  is it so, probably bugs in older versions of IE. Anyway commenting out the following lines in httpd-ssl.conf  brings back the missing .1:
BrowserMatch ".*MSIE.*" \
   nokeepalive ssl-clean-shutdown \
   downgrade-1.0 force-response-1.0

And voila after that only one roundtrip for SSL requests.....
Absolutely great :-)

Tuesday, November 18, 2008

Speed of light vs SSL

(Please see next post for update)
I have been trying to measure WAN efffect over an application I am working on. Due to a bug the application was running in SSL and I was quite surprised by the results.
After investigating it a little I want to share with you the following information. https (SSL) requests to the server involve two extra round trips for certificate authentication and key exchange. As a result a short HTTP request will require 3 times the network round trip time (6 times the latency). For example if latency is 90 ms and server time is 20ms https request will be 90*6+20= 560ms. While an http request will require 200ms. Quite impressive difference.
Saying that it is extremely important to reduce number of https requests to a server combining https requests is 3 times more important than regular http requests.