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High Performance Web Sites
book

High Performance Web Sites

by Steve Souders
September 2007
Intermediate to advanced content levelIntermediate to advanced
170 pages
4h 24m
English
O'Reilly Media, Inc.
Content preview from High Performance Web Sites

Edge Cases

The coordination of compression between servers and clients seems simple, but it must work correctly. The page could easily break if either the client or server makes a mistake (sending gzipped content to a client that can't understand it, forgetting to declare a compressed response as gzip-encoded, etc.). Mistakes don't happen often, but there are edge cases to take into consideration.

Approximately 90% of today's Internet traffic travels through browsers that claim to support gzip. If a browser says it supports gzip you can generally trust it. There are some known bugs with unpatched early versions of Internet Explorer, specifically Internet Explorer 5.5 and Internet Explorer 6.0 SP1, and Microsoft has published two Knowledge Base articles documenting the problem (http://support.microsoft.com/kb/313712/en-us and http://support.microsoft.com/kb/312496/en-us). There are other known problems, but they occur on browsers that represent less than 1% of Internet traffic. A safe approach is to serve compressed content only for browsers that are proven to support it, such as Internet Explorer 6.0 and later and Mozilla 5.0 and later. This is called a browser whitelist approach.

With this approach you may miss the opportunity to serve compressed content to a few browsers that would have supported it. The alternative—serving compressed content to a browser that can't support it—is far worse. Using mod_gzip in Apache 1.3, a browser whitelist is specified using mod_gzip_item_include ...

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Publisher Resources

ISBN: 9780596529307Errata Page