Web Application Performance - Revision history

Paul at 15:13, 11 July 2023

2023-07-11T15:13:01Z

← Older revision		Revision as of 15:13, 11 July 2023
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			== Introduction ==

	Two fundamental limits on performance:		Two fundamental limits on performance:

2023-07-11T15:12:50Z

← Older revision		Revision as of 15:12, 11 July 2023
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			Two fundamental limits on performance:

			* Amount of data
			* Distance (limited by speed of light - fast but not instant)

			Other considerations:

			* Number of requests - each one involves 1+ round trips (though can re-use connections)

	== Cache ==		== Cache ==

2023-07-11T15:09:59Z

Proxies / intermediates

← Older revision		Revision as of 15:09, 11 July 2023
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	* Difficult now that everything is HTTPS		* Difficult now that everything is HTTPS
			* No longer transparent for ISPs etc.
			* Can pay a cache provider

2023-07-11T15:09:22Z

Cache

← Older revision		Revision as of 15:09, 11 July 2023
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	* Gets around caching, effectively forces a new request by using a unique filename based on file contents		* Gets around caching, effectively forces a new request by using a unique filename based on file contents
	* Effectively allows you to set long expiry times but still force updates, e.g. 12 months for site logo		* Effectively allows you to set long expiry times but still force updates, e.g. 12 months for site logo

			=== Proxies / intermediates ===

			* Difficult now that everything is HTTPS

2023-07-11T15:08:23Z

Fingerprinting / hashing

← Older revision		Revision as of 15:08, 11 July 2023
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	* Gets around caching, effectively forces a new request by using a unique filename based on file contents		* Gets around caching, effectively forces a new request by using a unique filename based on file contents
			* Effectively allows you to set long expiry times but still force updates, e.g. 12 months for site logo

2023-07-11T15:07:50Z

← Older revision		Revision as of 15:07, 11 July 2023
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	== HTTP headers ==		== Cache ==

			=== HTTP headers ===

	* Cache-Control: max-age		* Cache-Control: max-age
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	* Can't override the browser behaviour - once it's cached with an expiry time		* Can't override the browser behaviour - once it's cached with an expiry time

			=== Fingerprinting / hashing ===

			* Gets around caching, effectively forces a new request by using a unique filename based on file contents

2023-07-11T15:05:40Z

HTTP headers

← Older revision		Revision as of 15:05, 11 July 2023
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	* If-Modified-Since: Date/time		* If-Modified-Since: Date/time
	* If-None-Match: Hash (ETag)		* If-None-Match: Hash (ETag)

			Problems:

			* Can't override the browser behaviour - once it's cached with an expiry time

2023-07-11T14:57:54Z

HTTP headers

← Older revision		Revision as of 14:57, 11 July 2023
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	Most headers won't help on first visit.		Most headers won't help on first visit.

	Request headers:		Request headers (conditional GET request):

	* If-Modified-Since: Date/time		* If-Modified-Since: Date/time
	* If-None-Match: Hash (ETag)		* If-None-Match: Hash (ETag)

2023-07-11T14:57:46Z

HTTP headers

← Older revision		Revision as of 14:57, 11 July 2023
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	Most headers won't help on first visit.		Most headers won't help on first visit.

			Request headers:

			* If-Modified-Since: Date/time
			* If-None-Match: Hash (ETag)

2023-07-11T14:52:19Z

HTTP headers

← Older revision		Revision as of 14:52, 11 July 2023
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	* Expires: Re-download after this		* Expires: Re-download after this
	* Last-Modified		* Last-Modified

			Most headers won't help on first visit.