"Offline mode for a mobile application, redux on server and a little bit about event sourcing." talk at React Native Camp by Viktor Turskyi
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Viktor Turskyi's presentation at the React Native Camp Conference 2018 discusses implementing offline mode in mobile applications using event sourcing and Redux architecture. He outlines the benefits of event sourcing, including improved audit trails, flexibility, and high performance, while providing a framework to build a training app that works on multiple platforms. The presentation also covers the necessary technologies and strategies for effectively managing events in a mobile and backend context.
"Offline mode for a mobile application, redux on server and a little bit about event sourcing." talk at React Native Camp by Viktor Turskyi
- 2. Offline mode for a mobile application Redux on server and a little bit about event sourcing Viktor Turskyi React Native CAMP Conference 2018
- 3. About me ● CTO at WebbyLab ● Open Source developer (Perl, JavaScript) ● 13 years in Software development ● Successfully delivered more than 60 projects
- 4. Classical 3-tier architecture Stateless Source: https://www.mrc-productivity.com/blog/2011/01/mobile-applications-why-architecture-matters/
- 7. What if your data is
- 9. Just huge list of immutable facts
- 10. Everything else is a cache
- 12. Classical approach (mutate state) Initial DB state: BALANCE 100USD User spends 30 USD New DB state: BALANCE 70 USD
- 13. Event sourcing (append fact) Initial DB state: FUNDS_ADDED 25 USD FUNDS_ADDED 61 USD FUNDS_SPENT 10 USD FUNDS_ADDED 24 USD User spends 30 USD New DB state: FUNDS_ADDED 25 USD FUNDS_ADDED 61 USD FUND_SPENT 10 USD FUNDS_ADDED 24 USD FUNDS_SPENT 30 USD
- 15. Why to use event sourcing? ● Build specific materialized views for different business domains ● Capture intent of the data, track user behaviour (not only results) ● Audit trail ● Possibility to rollback to any previous state ● Minimize data conflicts ● High processing performance (gracefully degrade on load, no locks) ● Flexibility to change format of materialized view (replay events)
- 16. Business task - create LMS for compliance ● Create training app (training == quiz): iOS, Android, Web ● Offline mode for mobile (read and write) ● Audit trail support ● Detailed analytics in mobile, web, nodejs ● Constantly evolving requirements to analytics
- 17. Mobile
- 18. Web
- 19. Session (user) metrics ● Training adoption burndown chart ● Adoption level ● Predict time to finish ● Spent time in training ● Monthly activity charts ● Spent time on each question
- 20. Training (group) metrics ● Training adoption burndown chart ● Aggregated students activity ● Adoption level for group ● etc
- 21. Technologies Mobile: React Native + Redux Web: React + Redux Backend: NodeJs + Mongo + Redux?
- 25. Merge Redux with event sourcing ● Client: create temporary queue ● Client: Add timestamp to every event ● Server: split event handlers into two parts: ○ Pure functions with business logic (reducer) ○ Side effects containing utils (db utils etc) ● Server: Use immutable structures for metrics. ● Client and Server share the same reducers
- 27. Now we do have offline mode for free
- 31. What do we use for events persistence in RN? RN AsyncStorage for redux store react-native-fs for large blobs (images, audio etc)
- 32. Events structure (mongoose schema)
- 33. Event handler initialization in app.js
- 35. Never mutate events Instead store reference to last applied event in metrics Track processed events
- 36. Code structure
- 37. Main issues to solve Mobile: Store larger number of events in offline mode Backend: Store events in a more suitable place (Kafka) Backend: Split the event queue into “realtime” and “delayed”
- 38. Links Event Sourcing pattern by Microsoft https://docs.microsoft.com/en-us/azure/architecture/patterns/event-sourcing Event Sourcing pattern by Martin Fowler https://martinfowler.com/eaaDev/EventSourcing.html "Turning the database inside out with Apache Samza" by Martin Kleppmann https://www.youtube.com/watch?v=fU9hR3kiOK0
- 39. Viktor Turskyi (koorchik) [email protected] https://twitter.com/koorchik https://twitter.com/webbylab https://github.com/koorchik https://github.com/webbylab http://webbylab.com