The 6 Rules for Modernizing Your Legacy Java Monolith with Microservices
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The 6 Rules for Modernizing Your Legacy Java Monolith with Microservices by Kevin Webber (@kvnwbbr)
Transcript of The 6 Rules for Modernizing Your Legacy Java Monolith with Microservices
The 6 Rules for Modernizing Your Legacy Java Monolith with Microservices
by Kevin Webber (@kvnwbbr)
A Legacy Monolith Story
heritage architecture» Single points of failure
» Impossible to scale out (shared mutable state, etc)
» Different non-functional requirements (reads, writes, compute)
» Optimized for none!
» Long, risky release cycles
How do Microservices help?
Microservices» Ubiquitous language
» Well defined models & boundaries
» Single responsibility
» Independently deployable, scalable, resilient
» Communicate via async messaging
» Own their data
» Don't expose a public API
Approach?Principles
» responsive, resilient, elastic, message-driven
Approach?Principles
» responsive, resilient, elastic, message-driven
Concepts
» bounded contexts (DDD), event sourcing, CQRS, CAP (eventual consistency)
Approach?Principles
» responsive, resilient, elastic, message-driven
Concepts
» bounded contexts (DDD), event sourcing, CQRS, CAP (eventual consistency)
Tools
» Typesafe Reactive Platform (Play, Akka, Spark)
Concepts and patternsWe will cover:
» Domain Driven Design (DDD)
» Async messaging
» API management
» Dependency management
» CQRS & event sourcing
» Transactions & ordering
Domain Driven Design
Getting started» Model sub-domain at package
level
» Tip: Visualize existing architecture with a tool like Structure101
» Define public RESTful API at package level (use async messaging inside package at service level)
» Refactor for physical separation, remove package
Going async
Async Benefits» Not wasting resources
» Memory, CPU, threads
» Embracing failure
» Not expecting a return from a remote service
» Designing for all scenarios
API management
API mgmt.» Messaging patterns
» Pub/sub, point-to-point, streaming
» API gateway
» Routing, aggregation, protocol translation
» Discovery
» Service discovery, registry, versioning
Dependency management
CQRS & event sourcing
Transactions and ordering
Considerations» ACID doesn't work across location/trust boundaries
» No 2-Phase commits (2PC)
» No holding locks for the duration of work
» In distributed systems we need to compensate for for failure rather than prevent failure
What next?
Microservices with Lightbend» Play for API gateway
» Akka for core microservices (DDD, CQRS, event sourcing)
» ConductR for cluster management (service registry, discovery, architecture visualization, security)
LagomMonolith to microservices
» Webinar: March 17, 1PM PST / 4PM EST
» https://www.lightbend.com/discover-lagom
» Ready-to-use connectors: event-sourcing, CQRS
» Launch all microservices with a single command
» Instantly visible code updates
Thank you!Visit https://www.lightbend.com/products/lightbend-reactive-platform to get started
Contact info
» Twitter: @kvnwbbr
» Email: [email protected]
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