# Technical decisions and issues log

## 2017-01-20 Unified build Spring Boot + React

Using the initial `src/main/js` was troublesome, because it didn't really follow any standard, and we would need a local
`build.gradle` to handle the frontend in order to be clean. It eventually made more sense to separate the react app 
sources in a subproject, following the example of [Geowarin Boot React](https://github.com/geowarin/boot-react/).

I wanted to make use of the local `package.json` scripts to be consistent with the development workflow and take 
advantage of Create React App's genericity. Some other nice plugins allowed for bundling, minification etc. directly 
from Gradle, but that's not exactly what I wanted. 

Using the [Gradle Node Plugin](https://github.com/srs/gradle-node-plugin) and its Yarn tasks allowed for an easy setup 
of the react frontend build. It already solved most of the frontend build problems: download node/npm/yarn, install 
dependencies, bundle the JS using the frontend tools... We just had to include the result of the frontend build into the
`static` folder of the backend jar.

#### Heroku issues

First problem with Heroku: it now tried to run `gradle stage` as it did not recognize a Spring Boot application anymore
in the root folder. I had to manually override the Gradle command in the app settings on Heroku to run a `gradle build`.

Second issue, the `gradle build` command actually runs the tests, which in the frontend subproject starts in watch mode, 
because not on a CI server (checking the environment variable `CI=true`). Also, the tests were already run by Travis CI,
so we did't in fact need them there. The final command for Heroku was `gradle assemble`, which does the job.
 
Third problem, the default web process for Heroku's dyno looked for jars in the `{projectRoot}/build/lib` folder. I had 
to add a Procfile to manually specify the `backend` subproject in the process command:

    web: java -Dserver.port=$PORT $JAVA_OPTS -jar backend/build/libs/*.jar

## 2016-12-08 React frontend

We decided to put the react stuff into `src/main/js` as it seems to follow the conventions. As `src/main/java` contains 
the Java sources, why not put the JavaScript sources in `src/main/js`?

Technical decisions:

- [Create React App](https://github.com/facebookincubator/create-react-app): because the front-end world evolves too 
fast to keep up with the tools!
- [Yarn](https://yarnpkg.com/) : for its performance and reliability compared to npm
- [Redux](http://redux.js.org/): because it seems to solve the state management problem really well, and sagas look 
promising
- [Immutable.js](https://facebook.github.io/immutable-js/): because Redux likes pure functions, and Immutable.js does a 
great job at enforcing it

So far, no special build including the produced static inside the webapp's Jar. Frontend and backend can be developed 
independently and both the frontend dev server and the spring boot server can run locally and communicate.

## 2016-12-04 Spring Boot backend

Technical decisions:

- [Websockets](https://en.wikipedia.org/wiki/WebSocket): as we want server pushes to reach all clients when a player 
plays a card, we chose Websockets as main transport. 

- [Spring Boot Websocket](https://spring.io/guides/gs/messaging-stomp-websocket/): because of my personal preference for 
and ease with the Java language, and because it is really quick to setup. It has the advantage to run without a 
container, with a simple `main()` method which also pretty cool.

- [STOMP](https://en.wikipedia.org/wiki/Streaming_Text_Oriented_Messaging_Protocol): coming with Spring official 
support, it was quite natural to use STOMP over Websockets as a subprotocol. It allows for an easier management of the 
payload and provide some sort of standard for the Publish/Subscribe mechanism.