Tworzenie wysokoskalowalnych systemów reaktywnych
Krzysztof Borowski
kborowski@agh.edu.pl
Trip plan
- Domain Driven Design
- Reactive Systems
- Reactive Programming
- ES and CQRS
- System as a whole
PhotoTrip App
- Mark on the map our trip
- Add photos
- Collaborate with others in real time
- Add Comments
Domain Driven Design
Bounded Context
Bounded Context is a central pattern in Domain-Driven Design. It is the focus of DDD's strategic design section which is all about dealing with large models and teams. DDD deals with large models by dividing them into different Bounded Contexts and being explicit about their interrelationships.
Martin Fowler
Bounded Context
Aggregate
- A cluster of domain objects that can be treated as a single unit.
- Aggregates domain objects and theirs behaviour
- Every change of the state within aggregate is transactional
Aggregates
Entity
- Has unique identificator
- Can mutate the state
- Contains other entities or value objects
case class Map(
id: MapId,
creatorId: String,
description: String
) Reactive Systems Space
Reactive System Definition
Systems spectrum
It is time to apply these design principles consciously from the start instead of rediscovering them each time.
Why should we care?
- Our software operates 24/7
- Dealing with high load, responding in milliseconds
- Solving more and more complicated domain problems
- The codebase is growing, software is evolving quickly
Problems
- Handling distributed architecture deployment
- Defining proper service boundaries
- Reliable messaging system
- Data streams, asynchronous communication
- Lack of well defined, tested in production frameworks
- Domain Driven Design (~2003)
- Persistent Messages Queues (Kafka (~2012))
- Reactive Programming (~2007)
- Lagom, Project Reactor (~2016)
- Containers & Orchestration (~2013)
Problems
Solutions
Reactive Programming
Reactive Programming
- reacting to changes
- often via data streams
- program using and relying on events instead of the order of lines in the code
Using reactive programming tools does not imply having a Reactive System!
Reactive Programming Marketplace
concepts: ReactiveX, Reactive Streams
ready to use: RxJava, RxKotlin, RxSwift, RxJS, Monix,
akka-streams, vert.x, Ratpack
Functional Reactive Programming?
Event Sourcing
Command/Query Responsibility Segregation
with ES
External Communication
