Advanced Caching Concepts @ Velocity NY 2015

5. ©2015 AKAMAI | FASTER FORWARDTM “40% MOBILE USERS WILL ABANDON IF PAGE LOAD >3s” Meanwhile… Source: Tammy Everts, SOASTAhttp://blog.radware.com/ applicationdelivery/applicationacc elerationoptimization/2015/02/wh y-you-should-care-about-mobile- web-performance/

6. ©2015 AKAMAI | FASTER FORWARDTM Source: Colin Bendell, Akamai “Convince your CFO that #perfmatters” @ Velocity SC 2015 http://goo.gl/eMqNog “PERFORMANCE CAN MAKE HAPPY USERS… …AND BUSINESS SENSE” CBC Case Study (FIFA World Cup 2014)  45% spike in traffic  30% faster  90-95% offload  REDUCED #servers @origin

7. ©2015 AKAMAI | FASTER FORWARDTM STEVE SOUDER’S 14 RULES FOR FASTER WEBSITES Rule 1 - Make Fewer HTTP Requests Rule 2 - Use a Content Delivery Network Rule 3 - Add an Expires Header Rule 4 - Gzip Components Rule 5 - Put Stylesheets at the Top Rule 6 - Put Scripts at the Bottom Rule 7 - Avoid CSS Expressions Rule 8 - Make JavaScript and CSS External Rule 9 - Reduce DNS Lookups Rule 10 - Minify JavaScript Rule 11 - Avoid Redirects Rule 12 - Remove Duplicate Scripts Rule 13 - Configure ETags Rule 14 - Make AJAX Cacheable

13. ©2015 AKAMAI | FASTER FORWARDTM Earlier, you ran a WebPagetest* for your (or a favorite) site. What rating did you get for “Cache Static Content”? i.A ii.B iii.C iv.D v.F *POLL * Use the private instance at http://wpt.advancedcaching.org

15. ©2015 AKAMAI | FASTER FORWARDTM #3 CACHE AS CLOSE TO USER AS YOU CAN Source: Ilya Grigorik, http://chimera.labs.oreilly.com/books/1230000000545/ch01.html#SPEED_FEATURE “We need to reduce round trips, move the data closer to the client, hide the latency through caching…” “Latency impedes bandwidth utilization”

21. ©2015 AKAMAI | FASTER FORWARDTM WHAT CONTROLS DO YOU HAVE? CACHE PARENT CACHE CHILD ORIGI N CDN BROWSER GATEWAY HTTP headers for browser cache Programmatic for localStorage (and ServiceWorker) HTTP headers HTTP headers CDN Config [ UI / API ] HTTP headers Reverse Proxy Config [ UI / API ]

23. ©2015 AKAMAI | FASTER FORWARDTM CACHE HIT RATIO COMMON TERMINOLOGY {#requests from cache} / {#total requests} CACHE MISS cache query results in object not in cache or stale STALE RESOURCE object has already expired, need to contact origin INVALIDATION remove content from cache ahead of expiry CONDITIONAL GET request resource only if modified

24. ©2015 AKAMAI | FASTER FORWARDTM CACHE-CONTROL BASIC HTTP RESPONSE HEADERS TTL and other directives EXPIRES Date/time stamp of future expiry ETAG Unique resource identifier LAST-MODIFIED Date/time stamp last modified at server VARY Add additional request parameters to cache key

25. ©2015 AKAMAI | FASTER FORWARDTM CACHE-CONTROL IMPORTANT HTTP CACHE DIRECTIVES MAX-AGE Time-to-live delta NO-STORE PRIVATE MUST-REVALIDATE Do not cache Meant to be cached only by single user, i.e. browser, not proxy Do not serve stale PUBLIC Can be cached by shared proxy

26. ©2015 AKAMAI | FASTER FORWARDTM TYPICAL CACHE INTERACTION (LAST-MODIFIED) CLIENT SERVER GET 200 OK Cache-control: <max-age> Expires: <date-time-stamp> Last-Modified: <date-time-stamp> GET If-modified-since: <last_modified_value> 200 OK or 304 Not Modified EXPIRES IN CACHE

27. ©2015 AKAMAI | FASTER FORWARDTM TYPICAL CACHE INTERACTION (ETAG) CLIENT SERVER GET 200 OK Cache-Control: <max-age> Expires: <date-time-stamp> Etag: “<string>” GET If-none-match: “<etag_value>” 200 OK or 304 Not Modified EXPIRES IN CACHE • Etags are often mis-configured, lead to cache pollution • Rely on Last-modified when you can • Useful when caching dynamic content, e.g. API responses

28. ©2015 AKAMAI | FASTER FORWARDTM CACHE KEYS HOST PATH QUERY ARGUMENTS/ ? By default, a web cache uses the following combination as primary key: Example – following represent different cached entities: www.example.com/en/logo.jpg www.example.com/jp/logo.jpg www.example.com/en/logo.jpg?len=100&height=100 www.example.com/en/logo.jpg?len=100&height=200 www.example.com/en/logo.jpg?len=100

29. ©2015 AKAMAI | FASTER FORWARDTM Which of the following HTTP status code is *not* cacheable by default? i. 404 Not Found ii. 301 Moved permanently iii. 200 OK iv. 302 Found v. 501 Not Implemented *POLL

31. ©2015 AKAMAI | FASTER FORWARDTM HOW TO DETERMINE TTL? Content Sensitivity Level CDN TTL Browser TTL None 7-30 days 2X median user session Low 12-24 hours 30 min or less Medium 15 min – 1 hour 10 min or less High 30 sec – 15 min 0 sec • If versioning assets, cache for VERY LONG time at CDN/browser • Otherwise:

32. ©2015 AKAMAI | FASTER FORWARDTM DUAL ENEMIES OF CACHE HIT RATE CACHE POLLUTION Different entries stored with same keyNeeded content evicted by excessive un-popular (potentially duplicate) entries CACHE COLLISION

33. ©2015 AKAMAI | FASTER FORWARDTM AVOID CACHE POLLUTION - TIPS HOST PATH height=600px/ ?Ignore Redundant Query Parameter width=800px utm_source=duck& &1 HOST PATH height=600px/ ?Re-order Query Parameters Alphabetically width=800px& height=600pxwidth=800px 2 ★ Rationalize across fragmented developer base Implement at CDN or origin reverse proxy: 3 Ignore Vary headers if possible. Instead, negotiate using custom logic Set downstream Cache- control: private to avoid pollution at proxy Vary: User-agent Vary: Referer

34. ©2015 AKAMAI | FASTER FORWARDTM AVOID CACHE COLLISIONS – RESS EXAMPLE ORIGIN CDN MOBILE USER DESKTOP USER version version Desktop content removed Mobile content removed SAME URL • Server conditionally assembles :: CDN conditionally caches • Device family string inserted into cache key: e.g. [android|iphone|ipad|desktop] • Set downstream • Vary: User-agent (to comply with SEO) • Cache-control: private to prevent caching on proxies

35. ©2015 AKAMAI | FASTER FORWARDTM HTTP POST CACHING POST /search HTTP/1.1 content-type: application/json host: https://www.example.com content-length: 47 {“Action”:“Search”,“Query”:“shirts”,“Pag e”:“1”} www.example.com search ed7fcd94e1f742ecf8573b622ded65cc/ ? ★ Use only for idempotent requests ★ Be careful with request size ★ Be cautious with PII data! Construct the appropriate cache key...

36. ©2015 AKAMAI | FASTER FORWARDTM PRE-FETCH / PRE-FRESH Prebrowsing - http://www.stevesouders.com/blog /2013/11/07/prebrowsing/ • Pre-fetch • Fetch object before client needs it • Can be used at browser (<link rel=“prefetch”…) and CDN • Prefresh • Re-validate asynchronously before cache expires • Can be used at browser (stale-while-revalidate, IE pre-check/post-check) and CDN

37. ©2015 AKAMAI | FASTER FORWARDTM CACHING PROTECTED CONTENT CDN AUTH SERVER STORAGE SERVER 1 6 3 2 4 5 1. USER REQUEST 2. AUTH REQUEST (HEAD) 3. AUTH RESPONSE 4. CONTENT REQUEST (ON MISS) 5. CONTENT RESPONSE (ON MISS) 6. USER RESPONSE USER ★ Ensure must-revalidate is ON ★ Great for large file downloads ? What if auth server doesn’t support HEAD?

38. ©2015 AKAMAI | FASTER FORWARDTM CACHING DYNAMIC PAGES Cache-able: Until this happens… Solution: • Serve from cache for non- logged in users • Bypass cache for logged in users • Use cookies to determine state (Much more to come in next section)

41. ©2015 AKAMAI | FASTER FORWARDTM HTML5 localStorage • Dedicated and robust client side storage • 5MB dedicated per domain • Scriptable, allows get/put/remove commands • Useful in FEO optimizations • e.g. decoupling JavaScript download from execution …Stay tuned for ServiceWorker

45. ©2015 AKAMAI | FASTER FORWARDTM RELY ON TTL 1 BROWSER EDGE ORIGIN GET GET 200 OK with cache directives* 200 OK with cache directives CONDITIONAL GET 200 OK (new object) 2 EXPIRES IN BROSWER CACHE CONTITIONAL GET 200 OK (new object) EXPIRES IN EDGE CACHE * Cache directives: cache-control expires last-modified etag OBJECT MODIFIED • Timestamp determined at time of caching via HTTP response • Offers graceful mechanism to retire stale content • Works on browsers, CDN and proxies

46. ©2015 AKAMAI | FASTER FORWARDTM INVALIDATING INVALIDATE 1 BROWSER EDGE ORIGIN GET GET 200 OK with cache directives 200 OK with cache directives CONDITIONAL GET 200 OK 2 EXPIRES IN BROSWER CACHE CONDITIONAL GET 200 OK* OBJECT MARKED AS EXPIRED OBJECT MODIFIED * Since object modified • Instruct cache to expire content but leave it in cache

47. ©2015 AKAMAI | FASTER FORWARDTM INVALIDATING (CONTD.) INVALIDATE 1 BROWSER EDGE ORIGIN GET GET 200 OK with cache directives 200 OK with cache directives CONDITIONAL GET 2 EXPIRES IN BROSWER CACHE CONDITIONAL GET 304 NOT MODIFIED OK* OBJECT MARKED AS EXPIRED * Since object not touched • Works for CDN/proxies, not browsers • Most CDNs provide both UI and API 304 NOT MODIFIED OK*

48. ©2015 AKAMAI | FASTER FORWARDTM PURGING PURGE 1 BROWSER EDGE ORIGIN GET GET 200 OK with cache directives* 200 OK with cache directives CONDITIONAL GET 200 OK 2 EXPIRES IN BROSWER CACHE [FULL] GET [ALWAYS] 200 OK OBJECT REMOVED FROM CACHE • Instruct cache to remove content • Works for CDN/proxies, not browsers • Most CDNs provide both UI and API

50. ©2015 AKAMAI | FASTER FORWARDTM RECOMMENDATIONS GOOD BETTER BEST Version assets and use very large TTLs Use TTLs apropos publishing needs Allow serving stale CDN TTL > Browser TTL for better control Execute invalidation/purge at non-peak times

52. ©2015 AKAMAI | FASTER FORWARDTM  LAMP Stack running on a single Amazon EC2 East instance.  Magento application layer, with “Madison Island” sample theme.  No CDN, No Browser Caching, No Origin Cache.  This will be our starting point… DEMO APPLICATION http://www.advancedcaching.org

60. ©2015 AKAMAI | FASTER FORWARDTM UNPREDICTABLE BROWSER CACHING From http://httpwg.github.io/specs/rfc7234.html#heuristic.freshness • "A cache may assign a heuristic expiration time when an explicit time is not specified…” • "If the response has a Last-Modified header field, caches are encouraged to use a heuristic expiration value that is no more than some fraction of the interval since that time (typically 10%)”. ★ Both Firefox and Chrome have implemented the heuristic freshness guidelines

64. ©2015 AKAMAI | FASTER FORWARDTM 1. Edit Apache httpd.conf and add a Directive to set Cache-Control Headers LoadModule expires_module modules/mod_expires.so LoadModule headers_module modules/mod_headers.so <IfModule mod_expires.c> ExpiresActive On ExpiresDefault "now" ExpiresByType image/gif "access plus 30 days" ExpiresByType image/jpeg "access plus 30 days" ExpiresByType image/png "access plus 30 days" ExpiresByType text/css "access plus 30 days" ExpiresByType text/javascript "access plus 30 days" ExpiresByType application/x-javascript "access plus 30 days" </IfModule> 2. Restart Apache 3. Test to confirm it worked. CONFIGURING CACHE-CONTROL AND EXPIRES HEADERS

67. ©2015 AKAMAI | FASTER FORWARDTM 1. Setup basic configuration on CDN 2. Configure cache TTLs on CDN 3. Define behaviors for un-cacheable content 4. Test site via CDN 5. Configure DNS to route traffic through CDN BASIC CDN SETUP

69. ©2015 AKAMAI | FASTER FORWARDTM BASIC CDN SETUP: CONFIGURE HOST AND ORIGIN IF INCOMING_HOST == “www.advancedcaching.org” THEN Set ORIGIN ADDRESS = “ec2-54-154-215-217.compute- 1.amazonaws.com” Set ORIGIN PORT = “80” Set FORWARD HOSTNAME = $INCOMING_HOST Set CACHE_KEY_HOSTNAME = $INCOMING_HOST Support gzip

70. ©2015 AKAMAI | FASTER FORWARDTM BASIC CDN SETUP: CACHING RULES IF ( FILE_EXTENSION == <list of cacheable extensions> ) THEN a) Set CDN Cache TTL to 30 days b) Allow content to be served stale if unable to validate c) Set downstream Cache-Control & Expires Lifetime = smaller of (origin header | remaining edge TTL) ELSE IF ( NOT_CACHEABLE ) THEN a) No-Store at CDN b) Pass downstream cacheability headers from origin

71. ©2015 AKAMAI | FASTER FORWARDTM BASIC CDN SETUP: TESTING 1. Confirm traffic is routing through CDN and cacheable content is Cached 2. Configure hosts file to route traffic through CDN 3. Test and verify site works as expected

73. ©2015 AKAMAI | FASTER FORWARDTM CONFIRMING CDN CACHE HITS http://wpt.advancedcaching.org/ • WebPageTest Private Instance w/ some modifications: 1. Extends Details tab Reports to include Cacheability Data 2. New Cache-Analysis tab for correlating Last-Modified w/ CDN Cache TTLs and Cache-Control/Expires headers 3. Automatically injects Akamai diagnostic headers

77. ©2015 AKAMAI | FASTER FORWARDTM IMPROVING OFFLOAD VIA CDN TIERED DISTRIBUTION Parent / child caches to maximize offload PRE-FETCH CONTENT Offload milliseconds before content requested PRE-FRESH CONTENT Update cached content before TTL expires

79. ©2015 AKAMAI | FASTER FORWARDTM • How old are the objects? • How long do browsers cache (cache- control) • What do we know about publishing process, i.e. versioned assets, schedules, etc.? DETERMINING APPROPRIATE CACHE TTLS?

80. ©2015 AKAMAI | FASTER FORWARDTM • For versioned assets, TTL should be very high. • For non-versioned assets, TTL for CDN should be higher than browser TTL • Consider what needs to happen when content is modified MANAGING CDN + BROWSER CACHING

82. ©2015 AKAMAI | FASTER FORWARDTM Using http://wpt.advancedcaching.org, run a WebPagetest Measurement and view the Cache Analysis Section. Do you see any opportunities to improve your caching strategy? i. Yes ii. No iii. Not Sure *POLL

85. ©2015 AKAMAI | FASTER FORWARDTM VARNISH CONFIGURATION backend default { .host = "54.152.215.217"; .port = "80"; .connect_timeout = 1s; .first_byte_timeout = 5s; .between_bytes_timeout = 2s; } sub vcl_recv { if (req.url ~ ".(png|gif|jpg|swf|css|js)$") { unset req.http.cookie; } } sub vcl_deliver { if (obj.hits > 0) { set resp.http.Varnish-X-Cache = "HIT"; } else { set resp.http.Varnish-X-Cache = "MISS"; } } /etc/varnish/default.vcl DAEMON_OPTS="-a :80 -T localhost:6082 -f /etc/varnish/default.vcl -S /etc/varnish/secret -s malloc,256m" /etc/default/varnish

86. ©2015 AKAMAI | FASTER FORWARDTM UPDATE CDN SETUP: CHANGE ORIGIN IF INCOMING_HOST == “www.advancedcaching.org” THEN Set ORIGIN ADDRESS = “54.152.215.217” Set ORIGIN ADDRESS = “52.91.239.172” Set ORIGIN PORT = “80” Set FORWARD HOSTNAME = $INCOMING_HOST Set CACHE_KEY_HOSTNAME = $INCOMING_HOST Support gzip

92. ©2015 AKAMAI | FASTER FORWARDTM Page is the same for all users, expect for certain conditions. • Example: homepage with mini cart coded in the HTML • This may be conditionally cached for some users, e.g. for un-signed user #2 CONDITIONALLY CACHEABLE PAGE

93. ©2015 AKAMAI | FASTER FORWARDTM Page is conditionally or unconditionally cacheable, but requires multiple version to be cached. • Example: homepage with multiple languages depending on the user’s context • Cache key modifications need to be made #3 DYNAMIC PAGE WITH MULTIPLE VARIATIONS

97. ©2015 AKAMAI | FASTER FORWARDTM Is anything different returned for 2 identical requests? $ diff -s <(curl -Lvs http://www.advancedcaching.org/ 2>&1) <(curl -Lvs http://www.advancedcaching.org/ 2>&1) < < Set-Cookie: frontend=uim2n3k6atbis4slovn9r5dpc1; expires=Sun, 04-Oct-2015 06:34:28 GMT; Max-Age=3600; path=/; domain=www.advancedcaching.org; HttpOnly --- > < Set-Cookie: frontend=dnjvcbvt9bsei7q1vhnfo68o81; expires=Sun, 04-Oct-2015 06:34:28 GMT; Max-Age=3600; path=/; domain=www.advancedcaching.org; HttpOnly TESTING DYNAMIC CONTENT FOR CACHEABILITY ★ Set-Cookie doesn’t impact our ability to cache dynamic HTML, provided the cache strips Set-Cookie from the response.

100. ©2015 AKAMAI | FASTER FORWARDTM Is there anything in the request indicating this is a logged in visitor with an item in their cart? Conclusion: The page is cacheable, but we don’t have enough information to determine it’s cacheability. TESTING DYNAMIC CONTENT FOR CACHEABILITY

101. ©2015 AKAMAI | FASTER FORWARDTM Cache part of the page Add indicators to conditionally cache Rewrite page to leverage Ajax/JSON for dynamic portions DEALING WITH NON-CACHEABLE DYNAMIC PAGES GOOD BETTER BEST

102. ©2015 AKAMAI | FASTER FORWARDTM 1. Cache the HTML <head> section of response at edge 2. Serve that while origin is generating rest of HTML 3. Serve the rest of the HTML once it is received ACCELERATING DYNAMIC PAGES - AKAMAI EDGESTART ★ This technique will accelerate render time, but provides no origin offload.

103. ©2015 AKAMAI | FASTER FORWARDTM • Set a “LoggedIn” cookie to indicate when user logs in, and a “ContentsInCart” cookie when a user adds an item to their cart. • This can be done at origin or at CDN • Cache page conditionally based on the cookie indicators • If request contains “LoggedIn=true” or “ContentsInCart=true” cookie, bypass cache and forward request to origin • Else serve response from cache CACHING DYNAMIC HTML

104. ©2015 AKAMAI | FASTER FORWARDTM Add To Cart operation: ./apps/magento/htdocs/app/code/core/Mage/Checkout/controllers/CartController.php Login operation: ./apps/magento/htdocs/app/code/core/Mage/Customer/controllers/AccountController.php UPDATING OUR DEMO APP setcookie("ContentsInCart", "true", time()+3600, "/", "www.advancedcaching.org"); setcookie("LoggedIn", "true", time()+3600, "/", "www.advancedcaching.org");

105. ©2015 AKAMAI | FASTER FORWARDTM CACHING DYNAMIC CONTENT CONDITIONALLY IF ( REQUEST_PATH == “/” OR “/akamai-polo.html” ) AND ( REQUEST_COOKIE “ContentsInCart” != “true” ) AND ( REQUEST_COOKIE “LoggedIn” != “true” ) THEN a) Set CDN Cache TTL to 1 day b) Allow content to be served stale if unable to validate c) Set downstream Cache-Control & Expires Lifetime = smaller of (origin header | remaining edge TTL

106. ©2015 AKAMAI | FASTER FORWARDTM WIDENING THE NET... IF ( FILE_EXT == html) AND ( REQUEST_PATH NOT (/checkout/* OR /account/* ) AND ( REQUEST_COOKIE “ContentsInCart” != “true” ) AND ( REQUEST_COOKIE “LoggedIn” != “true” ) THEN a) Set CDN Cache TTL to 1 day b) Allow content to be served stale if unable to validate c) Set downstream Cache-Control & Expires Lifetime = smaller of (origin header | remaining edge TTL ★ The ability to serve stale if unable to validate is extremely useful for dynamic content, especially if the origin is under stress or experiencing issues.

107. ©2015 AKAMAI | FASTER FORWARDTM CACHING SEARCH RESULTS http://www.advancedcaching.org/catalogsearch/result/?q=casual ★ When caching content such as this, there is a potential for cache pollution. Creating separate cache buckets for this content can mitigate the risk.

108. ©2015 AKAMAI | FASTER FORWARDTM OFFLOADING 3RD PARTY CONTENT 3rd party fonts are a SPOF, but required to render this page 2 additional DNS lookups + 3 TCP connections for loading content critical to the render path

110. ©2015 AKAMAI | FASTER FORWARDTM OFFLOADING 3RD PARTY CONTENT Serve fonts on the primary domain when possible • Requires code change at origin Rewrite HTML and perform forward re-writes at CDN to 3rd Party: • Requires no code changes at origin • Replace 3rd party hostnames from HTML & CSS • @CDN, match on filenames, fetch from alternative origin • Cache response at CDN GOOD BEST

112. ©2015 AKAMAI | FASTER FORWARDTM HTML FIND / REPLACE IF ( PATH CONTAINS “/” ) OR ( FILE_EXTENSION == “php” ) THEN a) Find “fonts.googleapis.com” b) Replace with “www.advancedcaching.org/googleapis/fonts.googleapis.com” IF ( PATH CONTAINS “/googlapis/fonts.googleapis.com” ) THEN a) Find “fonts.gstatic.com” b) Replace with “www.advancedcaching.org/gstatic/fonts.gstatic.com”

114. ©2015 AKAMAI | FASTER FORWARDTM FORWARD REWRITE RULE + CACHING IF ( PATH CONTAINS “/googleapis/” ) THEN a) Remove /googleapis/ from the URL b) Change the origin server to fonts.googleapis.com c) Set CDN Cache TTL to 7 days d) Allow content to be served stale if unable to validate e) Set downstream Cache-Control & Expires Lifetime = smaller of (origin header | remaining edge TTL

115. ©2015 AKAMAI | FASTER FORWARDTM FORWARD REWRITE RULE + CACHING IF ( PATH CONTAINS “/gstatic/” ) THEN a) Remove /gstatic/ from the URL b) Change the origin server to fonts.gstatic.com c) Set CDN Cache TTL to 7 days d) Allow content to be served stale if unable to validate e) Set downstream Cache-Control & Expires Lifetime = smaller of (origin header | remaining edge TTL

116. ©2015 AKAMAI | FASTER FORWARDTM OFFLOADING 3RD PARTY CONTENT - RESULTS BEFORE - Request #14. - DNS Lookup and TCP connection for single request - Start render at 0.9s AFTER - Request #4. - Render blocking CSS request prioritized by browser - No additional DNS overhead - TCP connection reused - Request is cached at the edge - Start render at 0.7s

117. ©2015 AKAMAI | FASTER FORWARDTM OFFLOADING 3RD PARTY CONTENT - RESULTS Accelerating resource critical render path will result in faster render time Offloading resource at edge and allowing it to be served stale eliminates the risk of SPOF 3rd PARTY CACHING ON 3rd PARTY CACHING OFF

123. ©2015 AKAMAI | FASTER FORWARDTM • Proactively increase the capacity of J.Crew’s web applications • Need to support traffic surges due to media events • Maximize performance for repeat visitors THE NEED FOR MAXIMIZING OFFLOAD

125. ©2015 AKAMAI | FASTER FORWARDTM REDIRECTS CONFIGURED AT THE CDN • Redirects can not be cached, but can be moved closer to the user • Configuring redirects at the CDN layer eliminates need for extra round trip to the origin • Redirects are location based

131. ©2015 AKAMAI | FASTER FORWARDTM 1. Cache as much of page as possible 2. Limit 3rd party content to reliable providers 3. Limit Ajax calls that are un-cacheable 4. Failover strategy: retry on error, serve custom error page with auto-refresh 5. CDN hosted waiting room for controlling origin load CACHING TECHNIQUES TO MITIGATE FLASH CROWDS

135. ©2015 AKAMAI | FASTER FORWARDTM • API provider -> Partner/Developer -> User • Others dictate release schedules • Risk of rogue implementations • Once spec’d, hard to update BEHOLDEN TO PARTNERS & DEVELOPERS

140. ©2015 AKAMAI | FASTER FORWARDTM • Cache dynamic, non-personalized responses • Use Etags • Rationalize URL parameters to avoid fragmentation - do it on edge or origin • Enforce uniform ordering of URL parameters Same Content, Multiple Keys: http://example.com/weather-data.asp?slat=47.43&slon=19.27&langid=20 http://example.com/weather-data.asp?slat=47.48&slon=19.28&langid=20 http://example.com/weather-data.asp?langid=20&slat=47.42&slon=19.29 http://example.com/weather-data.asp?langid=20&slat=47.41&slon=19.25 Rationalized: http://example.com/weather-data.asp?slat=47.40&slon=19.20&langid=20 http://example.com/weather-data.asp?slat=47.40&slon=19.20&langid=20 http://example.com/weather-data.asp?slat=47.40&slon=19.20&langid=20 http://example.com/weather-data.asp?slat=47.40&slon=19.20&langid=20 Rationalize + Re-order at edge or at origin using 302 2 - MAKE CACHING YOUR FRIEND

141. ©2015 AKAMAI | FASTER FORWARDTM • Most apps require entitlement on every request • Segregate authorization vs. content flows • Consider caching auth response at edge 3 - PROTECT AND PERFORM SIMULTANEOUSLY

142. ©2015 AKAMAI | FASTER FORWARDTM • Long TTLs preferred, but short ones will do • Enable cache-control & expires headers for client and gateway proxies • Implement failover • Avoid redirects • yadda, yadda, yadda 4 - USUAL RECOMMENDATIONS APPLY

146. ©2015 AKAMAI | FASTER FORWARDTM TOOLS WE USED TODAY Tool URL WebPageTest http://www.webpagetest.org WebpageTest Private Instance http://wpt.advancedcaching.org Google PageSpeed Insights https://developers.google.com/speed/pagespeed/insights/ Keynote KITE http://kite.keynote.com Soasta http://www.soasta.com REDbot https://redbot.org/ Charles Proxy http://www.charlesproxy.com/ Chrome DevTools https://developers.google.com/web/tools/setup/workspace/setup-devtools Akamai {OPEN} API https://developer.akamai.com/ https://community.akamai.com/community/developer/blog/2015/08/19/getting- started-with-the-v2-open-ccu-api?sr=stream

147. ©2015 AKAMAI | FASTER FORWARDTM ADDITIONAL INFORMATION Topic Author URL HTTP 1.1 Caching Specs IETF http://httpwg.github.io/specs/rfc7234.html A Practical Guide to Web Resource Caching – Parts 1 & 2 Pierre Lermant, Akamai https://blogs.akamai.com/2013/11/a-practical-guide-to-web- resource-caching-part-1.html https://blogs.akamai.com/2013/11/part-2-a-practical-guide-to- web-resource-caching.html Dynamic Content: A Short TTL as an Alternative to Purge Pierre Lermant, Akamai https://blogs.akamai.com/2014/12/dynamic-content-a-short-ttl- as-an-alternative-to-purge.html Measuring Impact of Page Caching Akshay Ranganath, Akamai https://community.akamai.com/community/web- performance/blog/2015/08/12/measuring-impact-of-page-caching Prebrowsing Steve Souders, SpeedCurve http://www.stevesouders.com/blog/2013/11/07/prebrowsing/

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