lecture11

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Unformatted text preview: Sheet1 Page 1 ----------------------- Page 1----------------------- CSE 135 Server Side Web Languages Lecture # 11 Web Performance Notes ----------------------- Page 2----------------------- CSE 135 Server Side Web Languages Lecture # 11 Core Ideas & To a user time passed matters not bytes sent & There is a difference between perceived time and actual time l Page paint time matter l Amount of screen refresh matters 8 Frames, Emphasis on reflows in HTML/CSS parse l How the screen refreshes matters 8 All at once vs. incrementally l Application pacing matters 8 Preloaders, travel search, etc. ----------------------- Page 3----------------------- CSE 135 Server Side Web Languages Lecture # 11 Core Ideas & To some Web owners bytes sent may matter quite a bit as well because of cost. & Obviously cost is bandwidth _E How much does 50K cost& nothing ( How much does 50K * thousands of customers cost maybe something? & Note the design focus of e-commerce sites, $ and bytes in content not in navigation & Heavy pages don E t just cause bandwidth they may cost hardware in terms of scalability, servers can l t be done with a connection as quick thus you will need more of them more quickly ----------------------- Page 4----------------------- CSE 135 Server Side Web Languages Lecture # 11 Speed is not just a simple case of bytes ----------------------- Page 5----------------------- Sheet1 Page 2 CSE 135 Server Side Web Languages Lecture # 11 Core Idea & & Golden Rule Golden Rule of Optimization & & Less data, less often& & Send as little as you need to as infrequently as you need to if you want to go faster Example: compression -> little to send Example: caching -> less frequent requests ----------------------- Page 6----------------------- CSE 135 Server Side Web Languages Lecture # 11 Scale != Speed & Adding more servers doesn& & t make a site faster y B Scaling does not mean faster unless things are overloaded & If a server is overloaded by offloading it, it may appear to go faster but in that sense the server was not operating at optimal efficiency & Do you know the tolerance& & of a server, connection, etc.? Number of concurrent connections it could handle, amount of traffic before the pipe is saturated, etc. ----------------------- Page 7----------------------- CSE 135 Server Side Web Languages Lecture # 11 Simple (Re)view to Think about Optimization <----Network----> HTTP Request Server Side Web Server programming Hardware technology Software Backend System User Agent of HTTP Response (e.g. Database) some sort CGI Apache, IIS, Apache Module, ISAPI Sheet1 Page 3 Zeus, etc. Scripting Tech (PHP) ----------------------- Page 8----------------------- CSE 135 Server Side Web Languages Lecture # 11 Optimizations Step by Step ----------------------- Page 9----------------------- CSE 135 Server Side Web Languages...
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This note was uploaded on 10/10/2010 for the course CSE CSE135 taught by Professor Powell during the Summer '10 term at UCSD.

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