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Pluu
Android Developer
GDG Korea Android Organizer
in Yanolja
Android + DI + KOIN = Easy?!
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Pluu Dev. 2
DIী ೠ ҙब
ߊ POINT.
01
02
03
KOIN ਵ۽ оߺѱ द
࢜۽ Ѫী ೠ ࢤп
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Pluu Dev. 3
Introduction
INDEX.
01
02
03
04
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What’s KOIN
Use KOIN
KOIN in Android
Pros / Cons
3
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Pluu Dev. 4
Instance Injection ⇪ ⇪ ⇪
new new new new new new
ٸ ਃೠ DI
Dagger V2
֫ ੋب / উೠ
֫ ੑ դب
… … …
оߺѱ द
ࢶ KOIN
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Pluu Dev.
Open/
closed
Liskov
substitution
Interface
segregation
Dependency
inversion
D
I
L
O
S
Single
responsibility
https://ko.wikipedia.org/wiki/SOLID_(ё_ೱ_ࢸ҅) 5
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DI
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Dependency Injection
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http://sys1yagi.hatenablog.com/entry/2017/06/24/220951
Android Clean Architecture
(Add Feature)
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What’s KOIN.
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KOIN
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"A pragmatic lightweight dependency injection
framework for Kotlin developers. Written in
pure Kotlin using functional resolution only: no
proxy, no code generation, no reflection!"
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KOIN 1.0.0 Unleashed
(18.09.14)
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Support
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Sample.
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class Repository()
class View()
class Presenter(
val repository : Repository
) Define
val appModule = module {
single { Repository() }
module("view") {
factory { View() }
factory { Presenter(get()) }
}
}
Sample
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class MyApplication : Application() {
override fun onCreate() {
super.onCreate()
startKoin(this, listOf(appModule))
}
}
class MySimpleActivity : AppCompatActivity() {
val firstPresenter: MySimplePresenter by inject()
}
Module
Start Inject
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KOIN DSL.
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Setup
// Add Jcenter to your repositories if needed
repositories {
jcenter()
}
dependencies {
// Koin for Kotlin apps
compile 'org.koin:koin-core:{revnumber}'
}
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KOIN DSL
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module Koin Module
factory Instance ࢤࢿ
single Singleton Instance ࢤࢿ
get Dependency Component ೧Ѿ
bind Bind ఋੑ
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Pluu Dev.
Define
class Repository()
class View()
class Presenter(
val repository : Repository
)
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val appModule = module {
single { Repository() }
module("view") {
factory { View() }
factory { Presenter(get()) }
}
}
https://gist.github.com/arnaudgiuliani/d343df6e08a997b2ff29f7542ca1f601#file-koin_1-0_dsl-kt
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val appModule = module {
single { Repository() }
module("view") {
factory { View() }
factory { Presenter(get()) }
}
}
Define
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Module
Singletone
Sub Module
Factory Instance
Factory Instance
- Injection
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Define - Log
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[context] create
[module] declare Single [name='Repository',class='Repository']
[module] declare Factory [name='view.View',class='View', path:'view']
[module] declare Factory [name='view.Presenter',class='Presenter', path:'view']
[modules] loaded 3 definitions
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Binding an interface
interface Service {
fun doSomething()
}
class ServiceImpl : Service {
override fun doSomething() { ... }
}
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val myModule = module {
single { ServiceImp() }
single { ServiceImpl() as Service }
single { ServiceImpl() }
}
https://insert-koin.io/docs/1.0/documentation/koin-core/index.html#_binding_an_interface
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Use KOIN.
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Binding an interface
class TestA(val service: Service)
class TestB(val service: ServiceImpl)
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val myModule = module {
single { ServiceImpl() }
factory { TestA(get()) }
factory { TestB(get()) }
}
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Pluu Dev.
(KOIN)::[e] Error while resolving instance for class 'Service' - error:
org.koin.error.NoBeanDefFoundException: No compatible definition
found for type 'Service'. Check your module definition
(KOIN)::[e] Error while resolving instance for class 'TestA' - error:
org.koin.error.BeanInstanceCreationException: Can't create definition
for 'Factory [name='TestA',class='TestA']' due to error : No compatible
definition found for type 'Service'. Check your module definition
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Binding an interface
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class TestA(val service: Service)
class TestB(val service: ServiceImpl)
val myModule = module {
single { ServiceImpl() }
factory { TestA(get()) }
factory { TestB(get()) }
}
bind Service::class
Binding an interface
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Naming a definition
val myModule = module {
single { ServiceImpl() }
single { ServiceImpl() }
}
val service : Service by inject()
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Exception in thread "main" org.koin.error.BeanOverrideException: Try to
override definition with Single [name='ServiceImpl',class='ServiceImpl'],
but override is not allowed. Use 'override' option in your definition or
module.
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Naming a definition
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Pluu Dev.
Naming a definition
val myModule = module {
single("default") { ServiceImpl() }
single("test") { ServiceImpl() }
}
val service : Service by inject(name = "default")
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Dealing with generics
module {
single { ArrayList() }
single { ArrayList() }
}
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Exception in thread "main" org.koin.error.BeanOverrideException: Try to
override definition with Single
[name='ArrayList',class='java.util.ArrayList'], but override is not allowed.
Use 'override' option in your definition or module.
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Dealing with generics
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Pluu Dev.
Dealing with generics
module {
single(name = "Ints") { ArrayList() }
single(name = "Strings") { ArrayList() }
}
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Declaring injection parameters
class Presenter(val view : View)
val myModule = module {
single{ (view : View) -> Presenter(view) }
}
val presenter : Presenter by inject { parametersOf(view) }
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startKoin
startKoin(listOf(module1,module2 ...))
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startKoin
fun startKoin(
list: List,
useEnvironmentProperties: Boolean = false,
useKoinPropertiesFile: Boolean = false,
extraProperties: Map = HashMap(),
logger: Logger = PrintLogger()
)
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startKoin
fun startKoin(
list: List,
useEnvironmentProperties: Boolean = false,
useKoinPropertiesFile: Boolean = false,
extraProperties: Map = HashMap(),
logger: Logger = PrintLogger()
)
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Modules
Koin Logger
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Modules &
Namespaces.
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KOIN Module.
Koin ܳ ೞח "ҕр"
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Module’s Path
fun module(
path: String = Path.ROOT,
createOnStart: Boolean = false,
override: Boolean = false,
definition: ModuleDefinition.() -> Unit
)
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Path
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Modules with paths
// definitions in / (root) namespace
val aRootModule = module { ... }
// definitions in /org/sample namespace
val sampleModule = module("org.sample") { ... }
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Modules with paths
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Root Path
Definition
Sub Path
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ALL EQUALS
module {
module("org.sample") {
// ...
}
}
module("org.sample") {
// …
}
module {
module("org") {
module("sample") {
// ...
}
}
}
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Pluu Dev.
Implicit definitions naming
val aModule = module {
module {
single { ComponentA() }
single { ComponentB(get()) }
}
module {
single { ComponentA() }
single { ComponentC(get()) }
}
}
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Empty
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Pluu Dev.
Directly
get(
name = "B.ComponentA"
)
Implicit definitions naming
val aModule = module {
module("B") {
single { ComponentA() }
single { ComponentB(get()) }
}
module("C") {
single { ComponentA() }
single { ComponentC(get()) }
}
}
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Pluu Dev.
Linking definitions between modules
// ComponentB <- ComponentA
class ComponentA()
class ComponentB(val componentA : ComponentA)
val moduleA = module {
single { ComponentA() }
}
val moduleB = module {
single { ComponentB(get()) }
}
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Visibility rules
// definitions in /
val rootModule = module {
single { ComponentA() }
}
// definitions in /org
val orgModule = module("org") {
single { ComponentB(...) }
}
// definitions in /org/sample
val sampleModule = module("org.sample") {
single { ComponentC(...) }
}
// definitions in /org/demo
val demoModule = module("org.demo") {
single { ComponentD(...) }
}
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CC
/sample
CA
/org
CB
CD
/demo
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Pluu Dev.
Start the container.
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Loading modules without startKoin function
/**
* Load Koin modules - whether Koin is already started or not
* allow late module definition load (e.g: libraries ...)
*
* @param modules : List of Module
*/
fun loadKoinModules(modules: List): Koin
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Stop Koin - closing all resources
fun stopKoin()
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Properties.
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Read/Write property from a KoinComponent
class MyComponent : KoinComponent {
fun doSomething() {
// Read a Koin property
val serviceUrl = getProperty("server_url")
// Set a Koin property
setProperty("isDebug",false)
}
}
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Read
Write
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Pluu Dev.
KOIN Components.
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KOIN Components.
What we need now is an API to retrieve our
instances outside of the container. That’s the goal
of Koin components.
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Start Koin with myModule
fun main(vararg args : String) {
// Start Koin
startKoin(listOf(myModule))
// Create MyComponent instance and inject from Koin container
MyComponent()
}
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Pluu Dev.
Use get() & by inject() to inject MyService instance
class MyComponent : KoinComponent {
// lazy inject Koin instance
val myService : MyService by inject()
// or
// eager inject Koin instance
val myService : MyService get()
}
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Pluu Dev.
Unlock the Koin API with KoinComponents
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by inject() Koin ஶపց ੋझఢझ ো ஂٙ
get() Koin ஶపց ੋझఢझ ஂٙ
release() ݽٕ ੋझఢझ ೧ઁ
getProperty() /
setProperty()
Property get/set
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Resolving instance from a name or a module
val module = module {
module("ComponentB") {
single { ComponentA() }
single { ComponentB(get()) }
}
module("ComponentC") {
single { ComponentA() }
single { ComponentC(get()) }
}
}
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class ComponentA
class ComponentB(
val componentA: ComponentA)
class ComponentC(
val componentA: ComponentA)
val a_b = get(
name = "ComponentB.ComponentA"
)
val a_c = get(
name = "ComponentC.ComponentA"
)
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Injection parameters.
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Multiple parameters
class Presenter(val view : View, id : String)
val myModule = module {
single { (view : View, id : String) -> Presenter(view, id) }
}
class MyComponent : View, KoinComponent {
val id : String ...
// inject with view & id
val presenter : Presenter by inject { parametersOf(this, id) }
}
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KOIN
in Android
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Setup
// Add Jcenter to your repositories if needed
repositories {
jcenter()
}
dependencies {
// Koin for Android
compile 'org.koin:koin-android:{revnumber}'
}
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Start Koin
class MyApplication : Application() {
override fun onCreate() {
super.onCreate()
// Start Koin
startKoin(this, listOf(appModule))
}
}
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Pluu Dev.
Injecting dependencies
class MySimpleActivity : AppCompatActivity() {
// Lazy injected MySimplePresenter
val firstPresenter: MySimplePresenter by inject()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//...
}
}
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inject() / get() ܳ
ా೧
Activity,
Fragment,
Service ١
Component ীࢲ
Koin ੋझఢझܳ
Ѩ࢝ оמ
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Pluu Dev.
ViewModel.
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Pluu Dev.
Setup
// Add Jcenter to your repositories if needed
repositories {
jcenter()
}
dependencies {
// Koin for Android - Scope feature
// include koin-android-scope & koin-android
compile 'org.koin:koin-android-viewmodel:{revnumber}'
}
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Injecting your ViewModel
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by viewModel()
Lazy Delegate Propertyܳ ࢎਊೞৈ
ViewModel Injection
getViewModel() ViewModel ੋझఢझܳ ஂٙ
sharedViewModel()
Lazy Delegate Property۽ ҕਬ ViewModel
Injection
getSharedViewModel() ҕਬ ViewModel ੋझఢझܳ ஂٙ
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Create a ViewModel class
class MyViewModel(val repo : HelloRepository) : ViewModel() {
fun sayHello() = "${repo.giveHello()} from $this"
}
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Writing the Koin module
val appModule = module {
// single instance of HelloRepository
single { HelloRepositoryImpl() }
// MyViewModel ViewModel
viewModel { MyViewModel(get()) }
}
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Injecting dependencies
class MyViewModelActivity : AppCompatActivity() {
// Lazy Inject ViewModel
val myViewModel: MyViewModel by viewModel()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_simple)
//...
}
}
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Injecting dependencies
class WeatherActivity : AppCompatActivity() {
/** Declare WeatherViewModel with Koin and allow constructor dependency
injection */
private val viewModel by viewModel()
}
class WeatherFragment : Fragment() {
/** Declare shared WeatherViewModel with WeatherActivity */
private val viewModel by sharedViewModel()
}
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■ औҊ ҙ
■ Logger ઓ
■ ۾द, ٘ ࢤࢿ, Reflection ࢎਊ
■ Fast Build
CONS
PROS
■ Service Locator Pattern
■ Overhead
■ Runtime Error
■ Constructor Injection Not
Support
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Easy
73
Moving from Dagger to Koin — Simplify your Android development
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Logger (1/2)
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https://github.com/InsertKoinIO/koin/tree/master/koin-projects/examples/coffee-maker
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Logger (2/2)
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https://github.com/InsertKoinIO/koin/tree/master/koin-projects/examples/coffee-maker
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Fast
Module / Compile time Dagger Koin
:app 41.610s 28.374s
:module1 26.363s 19.745s
module2 14.345s 11.325s
module3 7.241s 3.950s
module4 22.828s 5.866s
module5 4.976s 2.505s
module6 5.631s 4.684
module7 1.988s 3.178s
SUM 125.15s 79.59s
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Overhead
1.1.0 ѐࢶ
Injection Time in Kotlin Dagger 2.16 Koin 1.0.1 Kodein 5.3.0
Min-Max 0.03-9.48 ms 47.41-7.25 ms 7.48-15.48 ms
Average 0.12 ms 60.16 ms 7.63 ms
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https://martinfowler.com/articles/injection.html
■ != Dependency Injection Pattern
■ Factory Patternҗ ࠺त
Service Locator
Pattern
Instance Injection
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SEARCH
INSTANCE
in KOIN
01
02
03
04
05
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Target Scope
Resolve Instance
Module Definition
Single / Factory
Lazy / Direct Get
Declaring Injection
Find BeanDefinition
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Introduction
؊ Ө షۿ Reddit
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Dagger KOIN
BEST RESULT?
Developer / Architecture /
Setting / Search /
Testability / Scalability /
etc
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STEP
Module Search Refactoring startKoin
& injection
Step 01 Step 02 Step 03
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Pluu Dev.
■ From Dagger to Koin, a step by step migration guide
■ Inversion of Control Containers and the Dependency Injection
pattern
■ Moving from Dagger to Koin — Simplify your Android development
■ What is dependency injection?
ଵҊ
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THANK YOU FOR
WATCHING!
ANY QUESTIONS?