Christian Posta, principal architect at Red Hat discusses how to manage your data within a microservices architecture at the 2017 Microservices.com Practitioner Summit.

2. Full slide deck here:
h"p://bit.ly/ceposta-hardest-part

3. Twitter: @christianposta
Blog: http://blog.christianposta.com
Email: christian@redhat.com
Christian Posta
Principal Architect – Red Hat
• Author “Microservices for Java Developers”
• Committer/contributor Apache Camel, Apache ActiveMQ,
Fabric8.io, Apache Kafka, Debezium.io, et. al.
• Worked with large Microservices, web-scale, unicorn company
• Blogger, speaker about DevOps, integration, and microservices

5. People try to copy Net,lix, but they can only
copy what they see. They copy the
results, not the process.
Adrian Cockcro,, former Chief Cloud Architect, Ne6lix

6. “Microservices” is about optimizing … for speed.

7. How does your company go fast?

8. Manage dependencies.

9. Wait. What is data?

10. What is one “thing”?

11. Book checkout / purchase Title Search
RecommendaBons
Weekly reporBng

12. Focus on domain models, not data models
• Break things into smaller,
understandable models
• Surround a model and its
“context” with an explicit
boundary
• Implement the model in code
or get a new model
• Explicitly map between
different contexts
• Model transactional
boundaries as aggregates

16. SBck with these conveniences as long as you can.
Seriously.

17. But ...
• Load/size is too great to fit on one box
• Modules/use cases have different read/write characterisBcs
• Queries/joins are geOng too complex
• Security issues
• Lots of conflicBng changes to the model/schema
• Need denormalized, opBmized indexing engines
• We want to explicitly reduce dependencies on data between
our services

18. From here on out, what we’re saying is “thank you old
work-horse database, we’ve got it from here”…

19. “A microservice has its own database”

20. We’re now building a full-fledged
data-centric distributed system.
Some things to remember…

21. Plan for failures.
Build concepts of Bme, delay,
network, and failures into the
design as a first-class ciBzen.

24. h"ps://secure.phabricator.com/book/phabcontrib/arBcle/n_plus_one/

25. h"ps://secure.phabricator.com/book/phabcontrib/arBcle/n_plus_one/
getBulkHats()
getBulkHatsForCatsExcept()
wellReallyIJustWantCertainHats()
justExecuteThisSqlForMe()

26. We need “consistency”. But we expect failures. This is
starBng to sound like CAP…

27. Consistency models…
h"ps://en.wikipedia.org/wiki/Consistency_model
• Strict consistency (Linearizability)
• Sequential consistency
• Causal consistency
• Processor consistency
• PRAM consistency (FIFO)
• Bounded staleness consistency
• Monotonic read consistency
• Monotonic write consistency
• Read your writes consistency
• Eventual consistency

28. Replicated Data Consistency Explained through Baseball
(Doug Terry)
h"ps://www.microsoa.com/en-us/research/publicaBon/
replicated-data-consistency-explained-through-baseball/
• What consistency model do you need, depending on
what role you’re playing?
• What consistency model are you willing to pay for?
• Official score keeper? (Linearizability or RMW)
• Umpire? (Linearizability)
• Sports writer? (Bounded staleness, Eventual
consistency)
• Radio updates? (Monotonic read, Bounded staleness)
• Statistician (Bounded staleness)
• Friends in the pub (Eventual consistency)

29. Maybe we can use a relaxed consistency model
for some of those previously menBoned use cases…
...and solve for data-sharing issues while taking into
account the network and failures.

30. Example using sequenBal consistency…

31. What we’ve done is gone off and built a data system
at the applicaBon layer.

32. And this is what the internet companies did also.
(some even opensource!!)
• Yelp – MySQL Streamer
https://github.com/Yelp/mysql_streamer
• LinkedIn – Databus
https://github.com/linkedin/databus
• Zendesk – Maxwell
https://github.com/zendesk/maxwell

33. Meet debezium.io

35. Meet debezium.io

37. Twitter: @christianposta
Blog: http://blog.christianposta.com
Email: christian@redhat.com
Thanks for listening! Time for demo?
Full slide deck here:
h"p://bit.ly/ceposta-hardest-part