lecture11

lecture11 - CSE 135 Server Side Web Languages Lecture # 11...

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CSE 135 Server Side Web Languages Lecture # 11 Web Performance Notes
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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 • Page paint time matter • Amount of screen refresh matters – Frames, Emphasis on reflows in HTML/CSS parse • How the screen refreshes matters – All at once vs. incrementally • Application pacing matters – Preloaders, travel search, etc.
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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 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’t just cause bandwidth they may cost hardware in terms of scalability, servers can’t be done with a connection as quick thus you will need more of them more quickly
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CSE 135 Server Side Web Languages Lecture # 11 Speed is not just a simple case of bytes
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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
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CSE 135 Server Side Web Languages Lecture # 11 Scale != Speed • Adding more servers doesn’t make a site faster – 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.
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CSE 135 Server Side Web Languages Lecture # 11 Simple (Re)view to Think about Optimization HTTP Request Web Server Hardware & Software HTTP Response Backend System (e.g. Database) User Agent of some sort Server Side programming technology Apache, IIS, Zeus, etc. CGI Apache Module, ISAPI Scripting Tech (PHP) <----Network---->
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CSE 135 Server Side Web Languages Lecture # 11 Optimizations Step by Step
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CSE 135 Server Side Web Languages Lecture # 11 Web Overview: Steps 1 & 2 – The Request
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CSE 135 Server Side Web Languages Lecture # 11 Web Overview: Steps 1 & 2 – The Request
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CSE 135 Server Side Web Languages Lecture # 11 Main challenge is DNS which is both fragile and robust Don’t skimp on DNS servers Consider DNS replication or managed services • UltraDNS ( www.ultradns.com ) Consider using shortened and contingency names to help users Forget the www Minimal domains (e.g www.pint.com ~ pint.com) Contingency hosts • w, ww, wwww • All pretty much “free” just DNS entries Contingency domains
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lecture11 - CSE 135 Server Side Web Languages Lecture # 11...

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