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Get more than a cache back! The Microsoft Azure Redis Cache (NDC Oslo)

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Serving up content on the Internet is something our web sites do daily. But are we doing this in the fastest way possible? How are users in faraway countries experiencing our apps? Why do we have three webservers serving the same content over and over again? In this session, we’ll explore the Azure Content Delivery Network or CDN, a service which makes it easy to serve up blobs, videos and other content from servers close to our users. We’ll explore simple file serving as well as some more advanced, dynamic edge caching scenarios.

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Get more than a cache back! The Microsoft Azure Redis Cache (NDC Oslo)

  1. 1. Get more than a cache back! The Microsoft Azure (Redis) Cache Maarten Balliauw @maartenballiauw
  2. 2. Who am I? Maarten Balliauw Antwerp, Belgium Software Engineer, Microsoft Founder, MyGet AZUG Focus on web ASP.NET MVC, Azure, SignalR, ... Former MVP Azure & ASPInsider Big passion: Azure http://blog.maartenballiauw.be @maartenballiauw Shameless self promotion: Pro NuGet - http://amzn.to/pronuget2
  3. 3. Agenda Azure Cache Redis Data types Transactions Pub/sub Scripting Sharding/partitioning Patterns
  4. 4. Azure Cache
  5. 5. Caching on Azure Windows Server: AppFabric (“Velocity”) (2009-2010) Azure (ASP.NET cache) “Shared Cache” (AppFabric cache, multi-tenant) Self-Hosted Dedicated Cache Managed Cache (the above, but managed by Microsoft and with an SLA) A bit of history...
  6. 6. Caching on Azure 1920: Cache used to be a cache 2012: Cache became the go-to datastore Twitter stores 800 tweets / timeline in Redis New application types on Azure: PHP, Node, Java, ... Too much work to write AppFabric clients for all! http://www.redis.io/clients Way easier: just make it work on Windows and Azure New ways to develop applications
  7. 7. Redis
  8. 8. Redis “Redis is an open source, BSD licensed, networked, single-threaded, in-memory key- value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs.” REmote DIctionary Server
  9. 9. Redis Key-value cache and store (value can be a couple of things) In-memory (no persistence, but you can) Single-threaded (atomic operations & transactions) Networked (it’s a server and it does master/slave) Some other stuff (scripting, pub/sub, Sentinel, snapshot, …) Things to remember
  10. 10. So no persistence? Possible using a lot of I/O AOF (append-only files) RDB (Redis DB snapshots) With or without: all your data must fit in memory
  11. 11. Redis 101 demo
  12. 12. The Little Redis Book http://openmymind.net/redis.pdf By Karl Seguin
  13. 13. Data types Type Example Key Example value String cache:/home <html><head><title>Home page</title> Hash categories:1 Field name description numproducts Member Books Books for sale 50000 Set categories:1:products 20 11 56 89 32 4 List products:20:comments [0] -> “...” [1] -> “...” [2] -> “...” Sorted set products:bestsellers Field Eye Patch Parrot Score 84632 82120 + Bitmap, Hyperloglog
  14. 14. Data types demo
  15. 15. Data types Type Example Key Example value String cache:/home user:nextid <html><head><title>Home page</title> 2 Hash user:1 Field name handle Member Maarten @maartenballiauw Set user:1:followers 10 42 99 85 List user:1:timeline [0] -> { ... } [1] -> { ... } [2] -> { ... } Sorted set trending:no:tags Field #ndcoslo #redis Score 84632 82120 + Bitmap, Hyperloglog
  16. 16. Keys Good practice: use a pattern for keys E.g. users:1:maarten Get by id: KEYS users:1:* GET ...... Get by name: KEYS users:*:maarten GET ...... O(N) operation – use with caution!
  17. 17. But... .NET? Lots of options! http://www.redis.io/clients NuGet: ServiceStack.Redis StackExchange.Redis RedisAspNetProviders ...
  18. 18. Connecting to Redis from .NET demo
  19. 19. But... Azure? “It’s just Redis!” Main differences: auth mechanism and SSL support Use local for development from GitHub or NuGet (Redis-32 or Redis-64)
  20. 20. Azure Redis Cache demo
  21. 21. Azure Redis Cache Redis + Auth + SSL Monitoring Alerts Awesome tool: www.redsmin.com
  22. 22. Transactions MULTI, EXEC, DISCARD, WATCH No rollbacks (just discard queue) Failures are because of you, not Redis Optimistic locking with WATCH Only execute transaction queue if watched keys did not change
  23. 23. Transactions demo
  24. 24. Pub/Sub (P)SUBSCRIBE, UNSUBSCRIBE, PUBLISH Subscribe to a queue SUBSCRIBE news (or PSUBSCRIBE news:*) Send data to a queue PUBLISH news “This just in!” (optional) Keyspace notifications http://www.redis.io/topics/notifications CONFIG SET notify-keyspace-events KEA PSUBSCRIBE '__key*__:*' (or __keyspace@0__:foo)
  25. 25. Pub/Sub demo
  26. 26. Scripting Run Lua scripts on Redis http://www.redis.io/commands/eval EVAL ‘return “Hello, World!”’ 0 Scripts are cached (SCRIPT FLUSH) Scripts can be used as functions Although we must pass the body all the time (or use SCRIPT LOAD + EVALSHA) Helper functions available! Base, table, string, math, debug, struct, cjson, cmsgpack, redis.sha1hex
  27. 27. Scripting demo
  28. 28. What if I need more memory? Sharding! On client (consistent hashing) On server (Redis Cluster, not on Azure) Using a proxy (Twemproxy - https://github.com/twitter/twemproxy) var options = new ConfigurationOptions { EndPoints = { "my-server" }, Proxy = Proxy.Twemproxy };
  29. 29. Patterns
  30. 30. When can I use Redis? ASP.NET Output Caching (RedisAspNetProviders) ASP.NET Session State General-purpose cache Table Storage secondary index “Cache with benefits” Pub/sub Generally: when use case maps and data fits in RAM
  31. 31. When should I avoid Redis? More data than can fit in RAM Can use multiple, but even then: SUM(RAM) == max. data size Data and query model fits well in a relational model Materialize certain queries in Redis if needed Avoid Redis for large objects... ...with lots of concurrent read/write operations
  32. 32. Counting stuff How would you count “likes” if you were Facebook? Table Storage 1 entity per likeable entity + per server instance for writes, sum entities for read I/O and CPU time... SQL UPDATE ... Locking... Redis INCR post:12345 (Every once in a while, check keys to persist)
  33. 33. Counting stuff (2) How would you count “likes” if you were Facebook? And how would you get the 5 most popular posts? Use a sorted set Elements are scored (= # of likes) We can use ZREVRANGE to get the top X posts ZREVRANGE posts:likes 0 5 withscores
  34. 34. Get the latest 5 product reviews No need to go to the database Use a Redis List, truncated at 5 items Need more? Query the database
  35. 35. Rate limiting API should only allows 5 requests per 60 seconds Redis List Record 5 latest requests If we’re at 5, check the leftmost item versus current time 1 2 3 4 5 12:20:25 12:20:22 12:20:21 12:20:18 12:19:50
  36. 36. What’sUp? Sending short messages between parties, how to implement? Pub/Sub: Every user gets a subscription, others can send to that subscription Server listens on all subscriptions to archive/persist messages When user comes online, server can publish messages since last visit from archive/a Redis list
  37. 37. Autocompletion How to provide autocompletion over our million- records product catalog? SQL “LIKE” Lucene.NET / ElasticSearch Redis Sorted Set
  38. 38. Intersecting collections “Which friends do we have in common?” Algorithm could be: Find friends that we have in common Find friends they have in common Score the # of connections
  39. 39. Sort We have a series of bugs Priority, Status, Title, ... A user follows a few of these bugs How to store? How to query? (give me my top 5 bugs by priority)
  40. 40. Conclusion
  41. 41. Conclusion Azure Cache Redis is not just a cache Data types Transactions Pub/sub Scripting Sharding/partitioning Patterns 1 thing to remember: http://openmymind.net/redis.pdf
  42. 42. Thank you! http://blog.maartenballiauw.be @maartenballiauw http://amzn.to/pronuget2

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