Reark : a Reference Architecture for Android using RxJava (https://github.com/reark/reark) Description: Reark showcase a reference Architecture for Android application using Rxjava. This is an ambitious reference project of what can be done with RxJava to create an app based on streams of data and view models. presenter: Timo Tuominen (@tehmou) Timo is reactive programming specialist trying to make the world a better place - or at least the code. In addition to creating all kinds of apps and services, he enjoys teaching software development and is writing a book. This was presented at Futurice London's Beer & Tech event on 16.11.16.

1. reark.io
Powered by Futurice Spice Program

2. reark.io
Powered by Futurice Spice Program

3. reark.io
Powered by Futurice Spice Program
That’s 1952 stars

4. reark.io started
as an example
of how we do
things.

5. Now it has
library
components
as well.

6. Why native,
and not
React Native?

7. Who am I?

8. @tehmou
• Reactive
programmer

9. History of
reark.io

10. SAMSUNG KICK
Powered by Futurice

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

13. It was rebranded
into Goal+
summer 2016.

14. Statistics

15. Total Lines of Code
155384
(546410added,391026removed)
Total Commits
10103
Authors
31

16. Commit History
MWC Demo
Tablet release
(1089 commits in May)
Ramp up
Phone release

17. A lot of
challenges
keeping the code
together.

18. 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.

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

20. What
does the
app look
like?

22. Main
App
First there was an app.

23. Main
App
Store
View
“Database” to
hold the data and
publish updates.
What is shown on
the screen by the
platform.

24. Main
App
Store
View Model
View
Push updates to
the data.
Process the
raw data.
Display data.

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

26. Main
App

27. Main
App
Process
A process has its own “stack”,
which means that other processes
do not see variables in it.

28. Main
App
Process
Product owner wants to make a
cool new widget. It has to run in
its own “remote process”.
Process

29. Main
App
KICK Live
widget
ProcessProcess
Now we have two processes that
both have their own memory
space.

30. Main
App
KICK Live
widget
ProcessProcess
Store
But the Store is stuck in
one process.

31. Main
App
KICK Live
widget
ProcessProcess
Store
But the Store is stuck in
one process.

32. Main
App
KICK Live
widget
ProcessProcess
Store Move store into a
shared container.

33. Main
App
KICK Live
widget
ProcessProcess
Provide data
and changes to
all attached
processes.
Store

34. Store
What about
other devices
connected to
the phone?

35. Store
Gear
SmartTV

36. Store
Use Samsung web
socket bridge to
publish updates.

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

38. What’s in the
Store then?

39. On Android the
Store is traditionally
an database.SQLite
Also known as ContentProvider.

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

41. SQLite
- It’s been there since the beginning
- Can be shared across processes
- Allows to observe changes
- Asynchronous read / write

42. What’s the
problem?

43. SQLite
- …
- A pain to implement!

44. SQLite
- Nobody got time
for that!

45. What if there was a
way to start with a
simple Store that
could be later changed
into an SQLite?

46. reark.io
Powered by
Spice Program

47. reark.io
[x] Scalable Android Architecture
Powered by
Spice Program

48. Introduce an MVP
Store that can use
SQLite internally.

49. … or not use is it
until it is needed.

50. Generic App v0.1
Super simple proof
of concept.
Flickr: infinity7664

51. Generic App v0.01
Super simple proof
of concept.
Flickr: infinity7664
PO

52. Generic App v0.01
Super simple proof
of concept.
Flickr: infinity7664
This is just a
demo, it will
never go into
production!
PO

53. Generic App v0.01
Super simple proof
of concept.
Flickr: infinity7664
This is just a
demo, it will
never go into
production!
PO

54. Generic App v0.01
Super simple proof
of concept.
Flickr: infinity7664
This is just a
demo, it will
never go into
production!
PO

55. Generic App v0.01
Super simple proof
of concept.
Flickr: infinity7664
This is just a
demo, it will
never go into
production!
PO

56. Wrote an app that
was not going into
production Bad Luck
Brian

57. Wrote an app that
was not going into
production
It went into
production

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

59. The version 0.01
Super simple proof of concept
version. Everything in one
process.
Store
new HashMap<Integer, Beer>

60. The version 0.01
Store becomes a wrapper for the
HashMap. It is a simple key-value store.
Store
new HashMap<Integer, Beer>

61. The version 0.01
Store
new HashMap<Integer, Beer>
Great! But
how to get
beer out of
the store?

62. The version 0.01
Store
new HashMap<Integer, Beer>
Beer getBeer(Integer beerId)

63. The version 0.01
Store
new HashMap<Integer, Beer>
Beer getBeer(Integer beerId)
= Ask for beer, get beer immediately

64. The version 0.01
Store
new HashMap<Integer, Beer>
Beer getBeer(Integer beerId)
Not sure if KISS
Or the worst idea ever

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

66. Bad Luck
Brian
Wrote his app with
KISS

67. Wrote his app with
KISS
It didn’t scale

69. What’s the
minimum
interface for a
good Store?

70. Store interface
StorePut an item
at a time
Get a
stream of
items

71. Store interface
StorePut an item
at a time
Get a
stream of
items
(with the same id)

72. RxJava and
Observables

73. Observables in
very short
store.getBeer(beerId)
We define a way to
get beer from the
Store.

74. Observables in
very short
store.getBeer(beerId)
For this we need to
know the beerId

75. Observables in
very short
store.getBeer(beerId)
.subscribe(
We will subscribe to
the Observable. This
is like a callback.

76. Observables in
very short
store.getBeer(beerId)
.subscribe(
beer -> drink(beer)
);
We define the action
that is executed every
time a new beer
arrives.

77. Observables in
very short
store.getBeer(beerId)
.subscribe(
beer -> drink(beer)
);
Notice that we will
always get updated
versions of the beer
with the same id.

78. How it works in
real life.

79. Store interface
Beer Store
Let’s create a
beer Store.

80. Store interface
Beer Store
First
customer!

81. Store interface
Beer Store
Another subscriber to
the same beer!

82. Store interface
Beer Store
Someone pushes an
update to the Store.

83. Store interface
Beer Store
The update is
propagated to all
subscribers.

84. Store interface
Beer Store

85. Store interface
Beer Store
The subscribers have
processed the latest
update.

86. What about new
subscriber that
missed the beer?

87. Store interface
Beer Store
A new subscriber
arrives!

88. Store interface
Beer Store
The new subscriber gets the
latest value immediately to
get up to date.

89. Store interface
Beer Store

90. Store interface
Beer Store
All subscribers are again on
stand-by for new values.

91. The reark.io Store
design.

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

93. Store interface
interface StoreInterface <T, U> {
void put(T item);
Observable<T> get(U id);
}
The put operation is
fire and forger.

94. Store interface
interface StoreInterface <T, U> {
void put(T item);
Observable<T> get(U id);
}
The is no synchronous get,
only an observable.

95. The two main
reark.io Store
types.

96. MemoryStore
Flickr: infinity7664

97. MemoryStore
implements StoreInterface <T, U>
Flickr: infinity7664

98. MemoryStore
implements StoreInterface <T, U>
Flickr: infinity7664
Good for:
• Getting started
• No need to persist data
• Only one process running

99. ContentProviderStore
implements StoreInterface <T, U>
Flickr: Toti Maragliano

100. ContentProviderStore
implements StoreInterface <T, U>
The interface is
the same
Flickr: Toti Maragliano

101. ContentProviderStore
implements StoreInterface <T, U>
Flickr: Toti Maragliano
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

102. Case study:
Quickbeer Next
Powered by
Spice Program
https://github.com/apoi/quickbeer-next

103. App for ratebeer.com API
Wikipedia: “RateBeer has over 4.5 million ratings of almost
200,000 beers, from nearly 16,000 breweries”

104. Hand crafted by:
apoi
https://github.com/apoi/quickbeer-next
Powered by
Spice Program

105. Hand crafted by:
apoi
https://github.com/apoi/quickbeer-next
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.

107. Main Contributors

108. apoi
Main Contributors
Develops the framework against
his beer app as well as (secret)
customer projects.

109. apoi recuutus
Main Contributors
The Dagger master, also
does excellent reviews and
tests.

110. apoi tomaszpolanskirecuutus
Main Contributors
Figuring out
a way to put
his Options
library in the
example
project.

111. apoi tomaszpolanskirecuutus
Main Contributors
Figuring out
a way to put
his Options
library in the
example
project.

112. apoi tomaszpolanskirecuutus
Main Contributors
Figuring out
a way to put
his Options
library in the
example
project.

113. apoi tomaszpolanskirecuutus
Main Contributors
Figuring out
a way to put
his Options
library in the
example
project.

114. prt2121apoi tomaszpolanskirecuutus
Main Contributors
We don’t really know who he is, but
he sometimes updates libraries.

115. prt2121apoi tomaszpolanskirecuutus
Main Contributors
Started it, now drops in every once
in a while and annoys everyone by
rewriting stuff.
tehmou

116. Thank you.

117. Thank you.
(star us on reark.io)
@tehmou
Timo Tuominen

118. Extra case study:
Nautics Sailmate

120. “More convenient sailing”

121. This is a sea chart.

122. An offline package
is downloaded with
hundreds of Points
of Interest.

123. The POIs are
written all at once
into an SQLite
Store.
Store

124. Every part of the
app is updated
instantly when a
download finishes.
Store

125. fin.