This is a Conway's Game of Life simulation implemented in a reactive style using Project Reactor. I developed this code for my 2019 Apache Geode Summit Talk: Reactive Event Processing with Apache Geode.

The goal of the talk was to explore how Apache Geode fit into a reactive system. In the talk, and in this repository, you'll see how Geode fits into a distributed reactive system as an event producer, and as an event consumer. RSocket is used for network communication, and there's even a fun little browser-based visualizer based on Luca Sbardella's Gist.

Status

Gameserver produces allGenerations flux which can be consumed by:

• browser-based, JavaScript react-app
• Java-based testclient app
• Java-based recorder app, which feeds geodeserver Geode server

Build and Run

Works with OpenJDK 12 from Oracle and Adopt OpenJDK 12.

TODO

• enable BlockHound https://github.com/reactor/BlockHound
• upgrade RSocket to 1.0.0-RC2 or newer
• side project: figure out how to make Mono<Cell> put(final Mono<Cell> cellMono) work analogously to its Flux counterpart
• remove dependency on org.springframework.data:spring-data-commons in model module (necessary to make spring-data-geode serialization work)

Questions

1. putting a null reference into a Flux (or Mono) results in a puzzling "circularity" exception
2. why won't RSocket for Spring Messaging support e.g. Flux<String> return type or a String arg to a message mapping—primitive types aren't supported.
3. why must I my RSocket client app include a dependency on webflux to avoid crashing the RSocket server?

Run

To run just the reactive toy app: game server -> browser:

./gradlew :gameserver:bootRun

then, in another terminal:

cd react-app
npm start

After starting these in IntelliJ:

GeodeServerApplication -Xmx1g -Xms1g -Xss144k GameServerApplication RecorderApplication

use gfsh:

connect --locator=localhost[10334]
describe region --name=Cells