Notes 35 - HighPerformanceWebSites

Notes 35 - HighPerformanceWebSites - High Performance Web...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
High Performance Web Sites Much of the material derives from Steve Souders and Tenni Theurer of yahoo-inc.com 1 Copyright 2009 Horowitz
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The Importance of Front-End Performance The graph shows the time taken to download an html file and various associated image files, Javascript files, and the order of downloading; Note the time to download the html is a very small percentage of the total time 2 Copyright 2009 Horowitz
Background image of page 2
percentage of time spent on the front-end Where Is The Most Of The Time Spent Empty Cache Full Cache amazon.com 82% 86% aol.com 94% 86% cnn.com 81% 92% ebay.com 98% 92% google.com 86% 64% msn.com 97% 95% myspace.com 96% 86% wikipedia.org 80% 88% yahoo.com 95% 88% youtube.com 97% 95% A study of popular web pages and the time to download them showed that the vast majority of time is spent on the client side; This is true even if the page has been cached
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The Performance Golden Rule 80-90% of the end-user response time is spent on the front-end. So start there Greater potential for improvement Simpler to optimize Proven to work 4 Copyright 2009 Horowitz
Background image of page 4
80/20 Performance Rule Vilfredo Pareto: 80% of the consequences come from 20% of the causes Focus on the 20% that affects 80% of the end- user response time I.e. Start at the front-end 5 Copyright 2009 Horowitz
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Yahoo Interface Blog Most of the work done on how to Improve the performance of Web sites was done by Steve Souders and Tenni Theurer Working at Yahoo.com This blog site contains summaries of lots of the work performed by them www.yuiblog.com 6 Copyright 2009 Horowitz
Background image of page 6
Browser Cache Experiment An “empty cache” means the browser bypasses the disk cache and has to request all the components to load the page. A “full cache” means all (or at least most) of the components are found in the disk cache and the corresponding HTTP requests are avoided Experiment: Try to determine what the percentage of people is who load a home page when there are no elements of the page in the user’s cache? Solution: add a new image (a pixel) to your page, e.g. <img src=“image/blank.gif” height=“1” width=“1”/> With the following response headers: Expires: thu, 15 Apr 2008 20:00:00 GMT Last-Modified: Wed, 28 Sep 2009 23:49:57 GMT The Expires makes sure the page is not cached; the Last-Modified makes sure the server will have to check if blank.gif has changed Requests from a browser will have one of these response status codes 200 – the browser does not have the image in its cache 304 – the browser has the image in its cache, but needs to verify the last modified date Compute the following numbers: Percentage of users who view with an empty cache ::= (# unique users with at least one 200 response)/(total # unique users) Percentage of page views that are done with an empty cache ::= (total # of 200 responses) / (# of 200 + # of 304 responses) Copyright 2009 Horowitz 7
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
0.0% 10.0% 20.0% 30.0% 40.0% 50.0%
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 36

Notes 35 - HighPerformanceWebSites - High Performance Web...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online