The underappreciated power of content invalidation
- 1. APACHE SLING & FRIENDS TECH MEETUP 10-12 SEPTEMBER 2018 The underappreciated power of content invalidation Jakub Wądołowski, Cognifide (@jwadolowski)
- 2. 2https://flic.kr/p/c7a8iE There are only two hard things in Computer Science: cache invalidation and naming things. Phil Karlton
- 4. What can be cached? 4 ▪ HTTP response (body & headers) ▪ What makes response cacheable? ▪ Static assets only? ▪ Body encoding matters ▪ gzip, deflate, br, … https://flic.kr/p/EWtcyL
- 5. Caching layers 5 ▪ AEM (custom in-memory cache) ▪ Dispatcher ▪ CDN ▪ Web browser https://flic.kr/p/Vh2TXE
- 7. Invalidation models 7 ▪ TTL-driven ▪ Event-driven ▪ Mix of both https://flic.kr/p/Ra7cVb
- 8. Dispatcher invalidation 8 ▪ 3 primary techniques ▪ by folder level (statfile) ▪ TTLs ▪ resource only ▪ Extras ▪ refetching ▪ custom script https://flic.kr/p/mAYbSi
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- 12. Nothing fancy, huh? 12 ▪ Plenty of possibilities ▪ handle related resources ▪ invalidate CDN’s cache ▪ push data to external systems ▪ … https://flic.kr/p/qZygAC
- 14. The plan 14 ▪ High hit ratio & cache coverage ▪ Long TTLs (30+ days) ▪ AEM content changes reflected quickly ▪ Precise invalidation https://flic.kr/p/7F4bHa
- 15. Content view 15 ▪ Dispatcher mirrors AEM content structure ▪ SEO-optimized customer-facing URLs https://flic.kr/p/7rstvj
- 17. CDN cache 17
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- 20. Invalidation APIs 20 ▪ Multiple endpoints ▪ feature/authentication differences ▪ performance may vary ▪ Invalidation scope ▪ everything ▪ URL(s) ▪ tag https://flic.kr/p/dgfRgD
- 21. DAM assets 21 ▪ Sounds trivial? ▪ Renditions ▪ Alt texts ▪ Non-standard properties https://flic.kr/p/9d2MRh
- 27. Alt text (2/3) 27 ▪ Get all the pages that use given asset ▪ Query Builder API
- 29. Vanity URLs 29 ▪ Each page can have a number of easy-to- remember URLs ▪ Those pages are cacheable too https://flic.kr/p/GDprQk
- 33. Reusable components 33 ▪ Common elements (i.e. header) ▪ SDI (Sling Dynamic Include) to the rescue ▪ SSI (Server Side Includes) ▪ ESI (Edge Side Includes) https://flic.kr/p/dgghVK
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- 36. Tag-based invalidation (1/4) 36 ▪ Not everything can be wrapped into SSI/ESI ▪ Layout/templates ▪ HTML markup configs ▪ Is QueryBuilder the only option? https://flic.kr/p/25LNnfK
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- 42. Versioned clientlibs 42 ▪ Generally a good idea ▪ Does it fit well into CDN setup? https://flic.kr/p/9gTRKV
- 43. Cache-Control 43 ▪ public/private ▪ max-age=<seconds> ▪ must-revalidate ▪ no-cache https://flic.kr/p/5GCeGg
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- 45. We barely scratched the surface… 45 ▪ API throttling ▪ Error handling ▪ Payload limits ▪ Non-obvious content references https://flic.kr/p/pSB1rM
- 46. Lessons learned 46 ▪ purge all is dangerous ▪ make invalidation as precise as possible ▪ plan SSI/ESI since the very beginning ▪ QueryBuilder calls may require extra indexes https://flic.kr/p/dgge8U
- 47. 47 Thank you!