Reark : a Reference Architecture for Android using RxJava

reark.ioPowered by Futurice Spice Program

http://reark.io


http://reark.io


That’s 1952 stars

http://reark.io

reark.io started as an example of how we do

things.

http://reark.io

Now it has library

components as well.

Why native, and not

React Native?

Who am I?

@tehmou• Reactive

programmer

History of reark.io

http://reark.io

SAMSUNG KICKPowered by Futurice

Samsung KICK had an average score of 4.1 out of 5 on Google Play store, it was downloaded over 3 million times.

It was rebranded into Goal+ summer 2016.

Statistics

Total Lines of Code155384

(546410 added, 391026 removed)

Total Commits10103

Authors31

Commit HistoryMWC Demo Tablet release

(1089 commits in May)

Ramp up

Phone release

A lot of challenges keeping the code together.

Android 4.1.x has a bug that crashes it for view hierarchies deeper than ~30.

On a complex tablet application with nested fragments under 30 is a dream world.

- Big codebase- Large velocity- Long- “Satellite” apps

What does the app look

like?

Main App

First there was an app.

Main App

Store

View

“Database” to hold the data and publish updates.

What is shown on the screen by the platform.

Main App

Store

View Model

View

Push updates to the data.

Process the raw data.

Display data.

This is the MVVM architecture, you can see an example in the reark.io sample.

http://reark.io

Main App

Main App

Process

A process has its own “stack”, which means that other processes

do not see variables in it.

Main App

Process

Product owner wants to make a cool new widget. It has to run in

its own “remote process”.

Process

Main App

KICK Livewidget

ProcessProcess

Now we have two processes that both have their own memory

space.

Main App

KICK Livewidget

ProcessProcess

StoreBut the Store is stuck in

one process.

Main App

KICK Livewidget

ProcessProcess

StoreBut the Store is stuck in

one process.

Main App

KICK Livewidget

ProcessProcess

Store Move store into a shared container.

Main App

KICK Livewidget

ProcessProcess

Provide data and changes to

all attached processes.

Store

StoreWhat about

other devices connected to the phone?

Store

Gear

SmartTV

StoreUse Samsung web socket bridge to publish updates.

One Store for different uses:• Inside of one process• Between processes• Between physical devices

What’s in the Store then?

On Android the Store is traditionally an database.SQLite

Also known as ContentProvider.

SQLite- Can be shared across processes - Allows to observe changes - Asynchronous read / write

SQLite

- It’s been there since the beginning

- Can be shared across processes - Allows to observe changes - Asynchronous read / write

What’s the problem?

SQLite

- … - A pain to implement!

SQLite

- Nobody got time for that!

What if there was a way to start with a simple Store that

could be later changed into an SQLite?

reark.ioPowered by

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http://reark.io

reark.io[x] Scalable Android Architecture

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http://reark.io

Introduce an MVP Store that can use SQLite internally.

… or not use is it until it is needed.

Generic App v0.1Super simple proof of concept.

Flickr: infinity7664



PO



This is just a demo, it will

never go into production!

PO





PO





PO





PO

Wrote an app that was not going into

production Bad Luck Brian

Wrote an app that was not going into

production

It went into production

The version 0.01Super simple proof of concept version. Everything in one process.

Store

The version 0.01Super simple proof of concept version. Everything in one process.

Store

new HashMap<Integer, Beer>

The version 0.01Store becomes a wrapper for the HashMap. It is a simple key-value store.

Storenew HashMap<Integer, Beer>

The version 0.01

Storenew HashMap<Integer, Beer>

Great! But how to get beer out of the store?

The version 0.01

Storenew HashMap<Integer, Beer>Beer getBeer(Integer beerId)

The version 0.01


= Ask for beer, get beer immediately

The version 0.01


Not sure if KISS

Or the worst idea ever

SQLite- Can be shared across processes - Allows to track changes - Asynchronous read / write

Bad Luck Brian

Wrote his app with KISS

Wrote his app with KISS

It didn’t scale

What’s the minimum interface for a good Store?

Store interface

StorePut an item at a time

Get a stream of

items

Store interface

StorePut an item at a time

Get a stream of

items(with the same id)

RxJava and Observables

Observables in very short

store.getBeer(beerId)We define a way to get beer from the

Store.


store.getBeer(beerId)

For this we need to know the beerId


store.getBeer(beerId) .subscribe(

We will subscribe to the Observable. This

is like a callback.


store.getBeer(beerId) .subscribe( beer -> drink(beer) );

We define the action that is executed every

time a new beer arrives.


store.getBeer(beerId) .subscribe( beer -> drink(beer) );

Notice that we will always get updated versions of the beer

with the same id.

How it works in real life.

Store interface

Beer StoreLet’s create a beer Store.

Store interface

Beer Store

First customer!

Store interface

Beer Store

Another subscriber to the same beer!

Store interface

Beer StoreSomeone pushes an update to the Store.

Store interface

Beer StoreThe update is

propagated to all subscribers.

Store interface

Beer Store

Store interface

Beer StoreThe subscribers have processed the latest

update.

What about new subscriber that missed the beer?

Store interface

Beer Store

A new subscriber arrives!

Store interface

Beer StoreThe new subscriber gets the latest value immediately to

get up to date.

Store interface

Beer Store

Store interface

Beer StoreAll subscribers are again on

stand-by for new values.

The reark.io Store design.

Store interfaceinterface StoreInterface <T, U> { void put(T item); Observable<T> get(U id); }


The put operation is fire and forger.


The is no synchronous get, only an observable.

The two main reark.io Store types.

MemoryStore


MemoryStoreimplements StoreInterface <T, U>


MemoryStoreimplements StoreInterface <T, U>


Good for:• Getting started• No need to persist data• Only one process running

ContentProviderStoreimplements StoreInterface <T, U>

Flickr: Toti Maragliano


The interface is the same




Good for:• Persisting data if app is shut down• Sharing data between processes, i.e. widgets• If you have a bit of time to set up the SQLite

Case study: Quickbeer Next


https://github.com/apoi/quickbeer-next

App for ratebeer.com API

Wikipedia: “RateBeer has over 4.5 million ratings of almost 200,000 beers, from nearly 16,000 breweries”

Hand crafted by: apoi



Hand crafted by: apoi


Powered by Spice ProgramI have over 1100 beer

ratings on my ratebeer.com account that I use to test the app. You could say it’s well-brewed.

Main Contributors

apoi

Main Contributors

Develops the framework against his beer app as well as (secret) customer projects.

apoi recuutus

Main Contributors

The Dagger master, also does excellent reviews and tests.

apoi tomaszpolanskirecuutus

Main ContributorsFiguring out a way to put his Options library in the example project.







prt2121apoi tomaszpolanskirecuutus

Main Contributors

We don’t really know who he is, but he sometimes updates libraries.

prt2121apoi tomaszpolanskirecuutus

Main Contributors

Started it, now drops in every once in a while and annoys everyone by rewriting stuff.

tehmou

Thank you.

Thank you.(star us on reark.io)

@tehmou Timo Tuominen

http://reark.io

Extra case study: Nautics Sailmate

“More convenient sailing”

This is a sea chart.

An offline package is downloaded with hundreds of Points

of Interest.

The POIs are written all at once

into an SQLite Store.

Store

Every part of the app is updated instantly when a

download finishes.

Store

fin.

Reark : a Reference Architecture for Android using RxJava

Software