Net… work!

Yonatan Levin04/7/2016

Wifi: GoogleGuestPSKpass: pUp3EkaP

4

First,

Yonatan LevinGoogle Developer Expert

parahalllevin.yonatan

> 1200 members Largest Android Active Community

Yonatan LevinGoogle Developer

Expert & Android @ Gett

Idan FelixSenior Android &

Redhead Varonis

Jonathan Yarkoni

Android Developer & Advocate Ironsource

Android Academy Staff

Britt Barak

Android LeadStealth Startup

Muiriel Felix

Android Design

52 Cities > 20M usersRuby, Go, Python, Microservices

Logistics

https://www.facebook.com/groups/android.academy.ils/

What’s next?10/8 - Felix- Battery & CPU

14/9 - Britt- Threading

30 / 10 / 2016New course coming

Special Guest!

Program Manager at Google

What’s in menu?- Network- Offline- Scheduler- Batching- Pre-fetching- Whisky

What was I doing wrong?

Common errors- Polling chat/message from server every 5 seconds

even when app in the background- Pulling photos/articles from server every time user

opens the Gallery even when nothing is changed- Retrying failing networking requests till them will

succeed.- Service that never stops...- A lot of bugs :)

What actually happen

Example

Example

Two scenarios

I want it now!

Does it really works for most of the time?

What we want really to give the user?

Ideal world?

Let’s start with basics

1It’s also called HTTP

Net… work

Hypertext Transfer Protocol.This makes HTTP a stateless protocol. The

communication usually takes place over TCP/IP, but any reliable transport can be used. The default port for TCP/IP is 80, but other ports can also be used.

HTTP

URL

The protocol is typically http, but it can also be https for secure communications.

HTTP VerbSpecifying the action we want to perform on host

GET: fetch an existing resource. The URL contains all the necessary information the server needs to locate and return the resource.

POST: create a new resource. POST requests usually carry a payload that specifies the data for the new resource.

PUT: update an existing resource. The payload may contain the updated data for the resource.

DELETE: delete an existing resource.

Status CodeIn return, the server responds with status codes and message payloads

1xx: Informational Messages - Expect: 100-continue

2xx: Successful - 200 OK, 204 No Content

3xx: Redirection - This requires the client to take additional action. The most common use-case is to jump to a different URL in order to fetch the resource.

4xx: Client Error - 404 Not Found, 400 Bad Request,401 Unauthorized,

5xx: Server Error - 503 Service Unavailable

Request and Response Message Formats

Request and Response Message Formats

Request or response message

Request GETGET /articles/http-basics HTTP/1.1

Host: www.articles.com

Connection: keep-alive

Cache-Control: no-cache

Pragma: no-cache

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Response Format

HTTP-Version SP Status-Code SP Reason-Phrase CRLF

HTTP/1.1 200 OK

HTTP & HTTPS

A TCP stream is broken into IP packets, and it ensures that those packets always arrive in the correct order without fail. HTTP is an application layer protocol over TCP, which is over IP.

The total overlook

Should I connect every time?!

Persistent connection

Parallel connections

If there are six assets that the client needs to download from a website, the client makes six parallel connections to download those assets, resulting in a faster turnaround.

Pipelining

Server sideestablishing a socket to start listening on port 80 (or some other

port)

receiving the request and parsing the message

processing the response

setting response headers

sending the response to the client

close the connection if a Connection: close request header was found

2Because really there is only one

HTTP Client

URL url = new URL(myurl); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setReadTimeout(10000 /* milliseconds */); conn.setConnectTimeout(15000 /* milliseconds */); conn.setRequestMethod("GET"); conn.setDoInput(true); // Starts the query conn.connect(); int response = conn.getResponseCode(); is = conn.getInputStream();

// Convert the InputStream into a string String contentAsString = readIt(is, len); return contentAsString;

HttpURLConnection

Wait! I forgot something!

NetworkOnMainThreadException

Brave one that know how to implement readIt(InputStream

is)?

ReadIt()public String readIt(InputStream stream) throws IOException, UnsupportedEncodingException { Reader reader = null; reader = new InputStreamReader(stream, "UTF-8"); char[] buffer = new char[1024]; reader.read(buffer); return new String(buffer);}

What if it’s image?

Luckily, we have

Retrofit 2

A type-safe HTTP client for Android and Java

build.gradle

dependencies { ... compile 'com.squareup.retrofit2:retrofit:2.1.0' ...}

public interface UserService { @POST("me") Call<User>me();}Retrofit retrofit = Retrofit.Builder() .baseUrl("https://your.api.url/v2/"); .build();

UserService service = retrofit.create(UserService.class);

// the request url for service.me() is:// https://your.api.url/v2/me

OkHttp IntegratedRetrofit 2 relies on OkHttp as the HTTP client and has its own dependency to the library as well

compile 'com.squareup.okhttp3:okhttp:3.3.1'

OkHttpClient client = httpClient.build();Retrofit retrofit = Retrofit.Builder() .baseUrl("https://your.api.url/v2/"); .client(client) .build();

Why OkHttp called “Ok”?

InterceptorsOkHttpClient.Builder clientBuilder = new OkHttpClient.Builder();clientBuilder.connectTimeout(CONNECTION_TIMEOUT * 1000, TimeUnit.MILLISECONDS);clientBuilder.addInterceptor(mGTHeadersInterceptor);

Retrofit gtServiceRetrofit = new Retrofit.Builder() .baseUrl(mGTBaseUrl) .client(clientBuilder.build()) .addConverterFactory(GTResponseConverterFactory.create(mGson)) .build();

mGTServiceApi = gtTServiceRetrofit.create(GTServiceApi.class);

Interceptorspublic class GTHeadersInterceptor implements Interceptor {public Response intercept(Chain chain) throws IOException { Request original = chain.request();

// Customize the request Request request = original.newBuilder() .header("Accept", "application/json") .header("Authorization", "auth-token") .method(original.method(), original.body()) .build();

Response response = chain.proceed(request);

// Customize or return the response return response; }}

Sync Requestpublic interface UserService { @POST("/login") Call<User> login();}

// synchronousCall<User> call = userService.login();User user = call.execute().body();

ASycn RequestCall<User> call = userService.login();call.enqueue(new Callback<User>() { @Override public void onResponse(Call<User> call, Response<User> response) { // response.isSuccessful() is true if the response code is 2xx

}

@Override public void onFailure(Call<User> call, Throwable t) { // handle execution failures like no internet connectivity }}

Cancel requestCall<User> call = userService.login();User user = call.execute().body();

// changed your mind, cancel the requestcall.cancel();

Convertor

Available Converters

Gson: com.squareup.retrofit2:converter-gson:2.1.0

Moshi: com.squareup.retrofit2:converter-moshi:2.1.0

Jackson: com.squareup.retrofit2:converter-jackson:2.1.0

SimpleXML: com.squareup.retrofit2:converter-simplexml:2.1.0

ProtoBuf: com.squareup.retrofit2:converter-protobuf:2.1.0

Wire: com.squareup.retrofit2:converter-wire:2.1.0

Add convertorRetrofit retrofit = Retrofit.Builder() .baseUrl("https://your.api.url/v2/"); .addConverterFactory(ProtoConverterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build();

Multiple Convertors

First come - first serverFirst fail, pass to next neOne that succeed - consume the response.

Add the esoteric first and more general like GSON last.

הנקרא :הבנתI want to add query parameter to every request. What should i

do?

URL

The protocol is typically http, but it can also be https for secure communications.

Back to requests@GET("api/dbx/drivers/self/history/{page}/{items_per_page}")Call<JobsHistoryResponse> getDriverJobsHistory( @Path("page") int page, @Path("items_per_page") int itemsPerPage, @Query("date_from") String dateFrom, @Query("date_to") String dateTo);

api/dbx/drivers/self/history/1/30?date_from=”01012016”&date_to=”30012016”

Form@FormUrlEncoded@POST("api/dbx/orders/{order_id}/arrival_eta")Call<VoidResponse> postDriverExternalEtaBeforeArrival( @Header("Driver-Id") int mDriverId, @Path("order_id") int orderId, @Field("directions_eta") long directionsETA);

api/dbx/orders/1235675/arrival_eta

Body: { directions_eta=1235723847328 }

More read

https://futurestud.io/blog/retrofit-getting-started-and-android-client

Shot of whisky?

What if i need different BASE_URL for couple requests?

Download Image from S3public interface UserService { @GET public Call<ResponseBody> profilePicture(@Url String url);}

Retrofit retrofit = Retrofit.Builder() .baseUrl("https://your.api.url/"); .build();

UserService service = retrofit.create(UserService.class);service.profilePicture("https://s3.amazon.com/profile-picture/path");

http://youtube.com/v/-cSSiCghAdU

2Execute at right time

Schedulers

SyncAdapter

What is it and how i eat that

Android Framework API >= 7 (Android 2.1)Synchronizing data between an Android device and web serversYou specify what you should sync , how often - and it will do the rest

Benefits?

Plug-in architectureAutomated executionAutomated network checkingImproved battery performanceAccount management and authentication

Let’s compareCustom Sync Sync Adapter

Network Availability - manually Network Availability - Automatically

Pending Queue - manually Pending Queue - Automatically

Refresh on Network - manually Refresh on Network - Automatically

Periodic Update - manually Periodic Update - Automatically

Sync Setting - manually Sync Setting - Automatically

Network Bandwidth - manually Network Bandwidth - Automatically

Battery Efficient - ?? Depend on you Battery Efficient - Yes

Survive on Reboot - Depends on you Survive on Reboot - Yes

How to?

Sqlite Database: I guess you all are master of Sqlite database, SyncAdapter will store data in Sqlite using Content Provider. You may choose other options as well.

Content Provider: Act as bridge between your database and SyncAdapter. To expose your data in Rest like URL pattern.

AbstractAccountAuthenticator: We need to extend this class and override methods, It is primarily used to manage authentication and account management. To use SyncAdapter you must have custom account. This class is responsible to create account, maintain auth token.

How to?

Authenticator Service: This is normal Service, which we are using daily. The only difference is that this service create object of AbstractAccountAuthenticator class and bind.

AbstractThreadedSyncAdapter: As developer we need to extend this class and override methods. This is the main piece of SyncAdapter puzzle. It has method onPerformSync, in which we need to write our code.

Sync Service: This is normal Service. It use to create object of AbstractThreadedSyncAdapter class and bind.

How to?Authenticator.xml: You need to create this file under res/xml/ folder. This file is required to bind your authenticator component into the sync adapter and account frameworks, you need to provide these framework with metadata that describes the component. You can choose your own file name.

SyncAdapter.xml: You need to create this file under res/xml/ folder. The metadata specifies the account type you've created for your sync adapter, declares a content provider authority associated with your app.

AndroidManifest.xml: You must register Sync Service, Authenticator service and few other things in AndroidManifast file in order to work SyncAdapter, This is the final piece of puzzle.

JobScheduler/GCMNetworkManager

What?

Schedule the task to execute it when certain conditions met.(charging, idle, connected to a network or connected to an unmetered network)

Why two?

JobScheduler was introduced in API >= 21 (Lollipop).GCMNetworkManager - is part of GCM package. When using on devices >= 21, use JobScheduler underneath.

Deep Dive

build.gradle

dependencies { ... compile 'com.google.android.gms:play-services-gcm:9.0.2' ...}

AndroidManifest.xml<service

android:name="com.google.codelab.networkmanager.BestTimeService" android:permission="com.google.android.gms.permission.BIND_NETWORK_

TASK_SERVICE"android:exported="true">

<intent-filter> <action android:name="com.google.android.gms.gcm.ACTION_TASK_READY"/> </intent-filter>

</service>

BestTimeService.java/** * Task run by GcmNetworkManager when all the requirements of the scheduled * task are met. */public class BestTimeService extends GcmTaskService {

...}

BestTimeService.java@Overridepublic int onRunTask(TaskParams taskParams) { Log.i(TAG, "onRunTask"); switch (taskParams.getTag()) { case TAG_TASK_ONEOFF_LOG: Log.i(TAG, TAG_TASK_ONEOFF_LOG); // This is where useful work would go return GcmNetworkManager.RESULT_SUCCESS; case TAG_TASK_PERIODIC_LOG: Log.i(TAG, TAG_TASK_PERIODIC_LOG); // This is where useful work would go return GcmNetworkManager.RESULT_SUCCESS; default: return GcmNetworkManager.RESULT_FAILURE; }}

Activityprivate GcmNetworkManager mGcmNetworkManager;

@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ... mGcmNetworkManager = GcmNetworkManager.getInstance(this);}

Scheduling a taskTask task = new OneoffTask.Builder() .setService(BestTimeService.class) .setExecutionWindow(0, 30) .setTag(BestTimeService.TAG_TASK_ONEOFF_LOG) .setUpdateCurrent(false) .setRequiredNetwork(Task.NETWORK_STATE_CONNECTED) .setRequiresCharging(false) .build();

mGcmNetworkManager.schedule(task);

What’s in it?

Service: The specific GcmTaskService that will control the task. This will allow us to cancel it later.

Execution window: The time period in which the task will execute. First param is the lower bound and the second is the upper bound (both are in seconds). This one is mandatory.

Tag: We’ll use the tag to identify in the onRunTask method which task is currently being run. Each tag should be unique, and the max length is 100.

What’s in it?

Update Current: This determines whether this task should override any pre-existing tasks with the same tag. By default, this is false, so new tasks don’t override existing ones.

Required Network: Sets a specific network state to run on. If that network state is unavailable, then the task won’t be executed until it becomes available.

Requires Charging: Whether the task requires the device to be connected to power in order to execute.

Scheduling a periodic taskTask task = new PeriodicTask.Builder() .setService(BestTimeService.class) .setPeriod(30) .setFlex(10) .setTag(BestTimeService.TAG_TASK_PERIODIC_LOG) .setPersisted(true) .build();

mGcmNetworkManager.schedule(task);

What’s in it?

Period: Specifies that the task should recur once every interval at most, where the interval is the input param in seconds. By default, you have no control over where in that period the task will execute. This setter is mandatory.

Flex: Specifies how close to the end of the period (set above) the task may execute. With a period of 30 seconds and a flex of 10, the scheduler will execute the task between the 20-30 second range.

What’s in it?

Persisted: Determines whether the task should be persisted across reboots. Defaults to true for periodic tasks, and is not supported for one-off tasks. Requires “Receive Boot Completed” permission, or the setter will be ignored.

Cancel TaskmGcmNetworkManager.cancelAllTasks(BestTimeService.class);

mGcmNetworkManager.cancelTask( BestTimeService.TAG_TASK_PERIODIC_LOG, BestTimeService.class);

There is a problem hiding here

Not all devices shipped with Play Servicesint resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);if (resultCode == ConnectionResult.SUCCESS) { mGcmNetworkManager.schedule(task);} else { // Deal with this networking task some other way}

When Google Play updated it removes all scheduled periodic tasks

public class BestTimeService extends GcmTaskService {

@Override public void onInitializeTasks() { super.onInitializeTasks(); // Reschedule removed tasks here }}

4Predict what your user will need

Prefetch data

Prefetch strategy

The goal is simple: Reduce the number of radio activations required to download the data.

Result

Improve the latency, Lower the required bandwidthReduce download times.

User Experience!!!!!

Strategy

Download the data that has of 50% chance to be used by user in his sessionOrPrefetched data should be enough for 2-5 minutes of use

Let’s practice!

Example

4Minimizing the Effect of Regular UpdatesWith GCM/FCM

Triggered update

Polling

ServerOur App

Felix is dancing salsa?

No

Felix is dancing salsa?

NoFelix is dancing

salsa?

No

Felix is dancing salsa?

Yes!!!

http://youtube.com/v/mw6QQNd7uOQ

What if there is 50M clients?

GCM and FCM

GCM and FCM

How to

dependencies { compile 'com.google.firebase:firebase-messaging:9.2.0'}

<service android:name=".MyFirebaseMessagingService"> <intent-filter> <action android:name="com.google.firebase.MESSAGING_EVENT"/> </intent-filter></service>…<service android:name=".MyFirebaseInstanceIDService"> <intent-filter> <action android:name="com.google.firebase.INSTANCE_ID_EVENT"/> </intent-filter></service>

public class MyFirebaseInstanceIDService extends FirebaseInstanceIdService {

@Override public void onTokenRefresh() { // Get updated InstanceID token. String refreshedToken = FirebaseInstanceId.getInstance().getToken();

sendRegistrationToServer(refreshedToken); }}

https://fcm.googleapis.com/fcm/sendContent-Type:application/jsonAuthorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA{ "to" : "APA91bHun4MxP5egoKMwt2KZFBaFUH-1RYqx...", "notification" : { "body" : "great match!", "title" : "Portugal vs. Denmark", "icon" : "myicon" }, "data" : { "Nick" : "Mario", "Room" : "PortugalVSDenmark" }}

Message strategyNotifications delivered when your app is in the background. In this case, the notification is delivered to the device’s system tray. A user tap on a notification opens the app launcher by default.

Messages with both notification and data payload. In this case, the notification is delivered to the device’s system tray, and the data payload is delivered in the extras of the intent of your launcher Activity.

public class MyFirebaseMessagingService extends FirebaseMessagingService { @Override public void onMessageReceived(RemoteMessage remoteMessage) { Log.d(TAG, "From: " + remoteMessage.getFrom()); sendNotification(remoteMessage.getNotification().getBody()); }}

MyFirebaseMessagingService

4Don’t download that you already have

Redundant Download

Don’t download what you already have

Cache = Lastlong currentTime = System.currentTimeMillis();

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

long expires = conn.getHeaderFieldDate("Expires", currentTime);long lastModified = conn.getHeaderFieldDate("Last-Modified", currentTime);

setDataExpirationDate(expires);

if (lastModified < lastUpdateTime) { // Skip update} else { // Parse update}

How to do that in Retrofit?

4The shy guy that no shy anymore

Doze Mode

Doze, the bro :)

No network accessNo jobsNo syncsNo wakelocksNo alarmsGPS

Doze Mode on Marshmallow

Not shy anymore

Doze Mode on Nougat

Doze Mode on Nougat

Doze, bye- User pickup the phone- User plug the phone to the charger- Real alarm (clock) is going to kick on

So how i survive my background service to track

Felix?

Will doze mode affect my app?

GCM

Use GCM with High priority - but treat it with special care{ "to" : "...", "priority" : "high", "notification" : { ... }, "data" : { ... }}

AlarmManager

setAndAllowWhileIdle() or setExactAndAllowWhileIdle().

Could be triggered only once in every fifteen minutes

WhiteList

An app can fire the ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS intent to take the user directly to the Battery Optimization, where they can add the app.

An app holding the REQUEST_IGNORE_BATTERY_OPTIMIZATIONS permission can trigger a system dialog to let the user add the app to the whitelist directly, without going to settings. The app fires a ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS Intent to trigger the dialog.

The user can manually remove apps from the whitelist as needed.

WhiteList

An app holding the REQUEST_IGNORE_BATTERY_OPTIMIZATIONS permission can trigger a system dialog to let the user add the app to the whitelist directly, without going to settings. The app fires a ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS Intent to trigger the dialog.

Note: Google Play policies prohibit apps from requesting direct

exemption from Power Management features in Android 6.0+ (Doze and

App Standby) unless the core function of the app is adversely

affected.

Payload

Because size is matter4

Serialization

Flatbuffers4

Serialization/Deserialization

Serialization

Deserialization

JSON Class Representation

{ "starwars": { "number_of_episodes": 1, "realDarthVaderName": "Anakin Skywalker", "nextEpisodeRelease": "01-12-2016 01:00:00+3:00GMT" }}

Serialization/Deserialization

Advantage - It’s human readable. And it’s biggest weak point.

Memory overhead

- Faster- Lighter

FlatBuffers

How it works?

Process

1.Create schema2.Compile schema with flatc compiler3.Import generated files into your project4.Read from byte[]:

java.nio.ByteBuffer buf = builder.dataBuffer();// Deserialize the data from the buffer.StarWars starWars = StarWars.getRootAsStarWars(buf);