Event Sourcing in less than 20 minutes - With Akka and Java 8
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The document discusses event sourcing and Command Query Responsibility Segregation (CQRS) in modern software architecture, emphasizing the benefits of using frameworks like Lagom for building reactive microservices. It outlines how Lagom enables developers to create scalable, maintainable systems while maintaining architectural integrity through principles such as event sourcing and asynchronous messaging. The presentation also addresses the challenges in enterprise software development and advocates for adopting frameworks that abstract complexities to improve developer productivity.
Event Sourcing in less than 20 minutes - With Akka and Java 8
- 1. Kiki Carter Enterprise Architect May 2017 Event Sourcing and CQRS in 20 minutes with Akka & Java 8
- 2. Lightbend Headquarters in San Francisco & Lausanne, Switzerland >2 million downloads Lightbend Reactive Platform Originators of the Reactive Manifesto >17,000 signers Reactive Experts in 20 Countries around the globe
- 3. About me Some things I like Some things I don’t like IG: @thatskiki Heights Wild wildlife Unintentional Sharing These things
- 4. Why are we talking about this anyway?
- 5. Not really *new* buzzwords
- 6. Legacy App Modernization (is a thing again)
- 7. Distributed Systems(for real this time)
- 8. A system of autonomous collaborative distributed services
- 9. Autonomy From Greek Auto-nomos: auto meaning self nomos meaning law
- 11. Think in Promises not Obligations
- 12. “Autonomy makes information local, leading to greater certainty and stability” - In Search for Certainty by Mark Burgess
- 13. No one can tell my story better than I can…
- 14. Obligations diverge into unpredictable outcomes from definite beginnings ⇒ decreased certainty Promises converge towards a definite outcome from unpredictable beginnings ⇒ improved certainty
- 16. An Autonomous Service can only Promise its own Behavior
- 17. How do we get there? (irl)
- 18. Data Center A eCommerce server eCommerce server eCommerce server Database Database Data Center B eCommerce server eCommerce server eCommerce server Database Database Heritage Distributed Systems
- 22. I’m eating it!
- 23. I’m eating it!
- 24. I’m eating it!
- 26. But wait, there’s more!
- 29. User order cart Shop data User order cart Shop data data data data May not be accurate – probably isn’t
- 30. It’s not the things, it’s the things that happen #facts
- 32. Example: Instead of a shop service, events that happen within the shopping context
- 33. What happens to our state?
- 34. First: A true story
- 36. Shopping context data data events events events Stateless Gateway entity entity entity state state state Akka Persistence commands
- 37. In Akka Persistence: key structures Command Events State Events Events
- 38. Inside your persistent Actor:
- 39. Anatomy:
- 40. Anatomy:
- 41. Recovery, a first class concept:
- 42. Why bring cqrs along?
- 43. The world revolves around events:
- 44. command command command eventevent eventeventevent event state Snapshots | Events Read-side representation queries Read-side processing Read-only command
- 45. And if you need to share facts outside of your context boundary…
- 46. command command command eventevent eventeventevent event state Snapshots | Events distributed pub-subRead-only command Read-side representation queries Read-side processing Service A Service B
- 47. Technology Implications • The storage system becomes an additive only architecture • Append-only architectures distribute • Far fewer locks to deal with • Horizontal Partitioning is difficult for a relational model
- 48. Business Implications • Criteria is tracked from inception as an event stream • You can answer questions form the origin of the system • You can answer questions not asked yet! • Natural audit log
- 49. Questions?
- 50. An Open Source framework for building micro service systems
- 51. Rate of change with levels of abstraction Low level languages High level languages Libraries / packages Application Frameworks Application Networking System Building Frameworks Rate of change Levels of abstraction
- 52. Shopping context data data events events events Stateless Gateway entity entity entity state state state Akka Persistence is focused in the entity commands
- 53. Web Application Framework Concurrency Toolkit Runtime Thin, powerful abstraction over Microservice system framework Other curated tools, architectural principles and patterns used for building reactive microservice systems
- 54. Enterprise Challenge Build faster Maintain architectural integrity as you move fast Enterprise software development is a high stakes game Success is high reward, failure is high risk
- 55. Too Many Choices Analysis Paralysis Challenge
- 56. Lagom makes reasonable choices for you. It’s built on message-driven technology that’s highly responsive, elastic and fault- tolerant. It’s Reactive.
- 57. Lagom Components Akka – Persistence, PubSub, Cluster, Streaming Async Services Play Framework – Web framework Cassandra – managing data persistence Guice – dependency injection SLF4J & Logback – Logging Typesafe Config – configuration JSON Serialization – Play JSON (Scala) Jackson (Java) Service Gateway Message Broker - Kafka
- 58. Difficult to Consistently Scale Architectural Integrity Challenge
- 59. Lagom consistently applies patterns for Reactive System Building
- 60. Architectural Principles Enforced by Lagom Single Responsibility Principle Service Oriented Architecture Encapsulation Hexagonal Architecture
- 61. Asynchronous & Non Blocking Event Sourcing Command query responsibility segregation Eventual Consistency Domain Driven Design (Bounded Contexts, Context Maps, Aggregate Entities) Service Locator Discovery Edge Service Lagom Design Patterns Key Patterns Required when building distributed reactive microservice systems Circuit Breaker
- 64. Experts Required You don’t need “Lagom developers” just Scala or Java developers willing to apply Lagom semantics.
- 66. Practical Productivity Scala & Java API Use Any IDE Quick Start w/ Batteries Included Hot Reload & Single Command to Runall Developer productivity is a core feature of the Framework
- 67. Unplanned Complexity or Chaos Challenge
- 69. You cannot simply break the seal and expect everything to function correctly
- 70. Lagom minimizes chaos through isolation, autonomous services
- 71. Lagom Encourages and Enables You to Contain Mutable State & Publish Facts
- 73. Lagom Allows You to Untangle Read & Write Models with CQRS & Event Sourcing
- 74. Lagom uses asynchronous messaging, asynchronous IO & distributed persistence patterns
- 75. client command command node node node node Reactive programming RES T messaging streaming Stateless Behavior node Reactive programming Stateful Entity Write model event log DS Event (fact) Event (fact) Read model query db DS Event (fact) Event (fact) Service discovery Service gateway Authentication … command command command ReactiveSystem
- 76. All or Nothing This and Everything Challenge
- 78. Lagom & your Legacy • Language agnostic communication with external services • Safe Interaction with legacy systems via circuit breakers • No need to tear everything down and start over • Embraces polyglot systems
- 79. With Withoutor Governance, Templates, Ref Apps, Documentation, scaling architecture expertise, etc. Boot Reactor Kafka Cassandra Netflix Patterns asynchronous REST streaming CQRS Event Sourcing Eventual consistency DDD Service locator Java Eventuate Axon Spring Cloud … Play Akka Kafka CassandraScala Patterns asynchronous REST streaming CQRS Event Sourcing Eventual consistency DDD Service locator Java
- 80. In Summary In order to keep up with the pace of change and maintain architectural integrity as you move, try using a framework that provides an abstraction above the application level – at the system level. ….and what if you don’t?
- 81. Try Lagom • www.lagomframework.com , https://github.com/lagom • Basic example “Hello World” - https://www.lagomframework.com/get-started-scala.html • More robust example “Online Auction” - https://github.com/lagom/online-auction-scala • Ask me for a demo: • [email protected] • Twitter: @kikisworldrace
- 82. Questions?