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Android Tracker 0.4.0

Ihor Tomilenko edited this page Apr 27, 2017 · 3 revisions


This page refers to version 0.4.0 of the Snowplow Android Tracker.

Documentation for older version of this tracker is available:

Integration Guide:

Local Testing:


1. Overview

The Snowplow Android Tracker allows you to track Snowplow events from your Android applications and games. It supports applications using the Android SDK 11 and above.

The tracker should be straightforward to use if you are comfortable with Java development; its API is modelled after Snowplow's Python Tracker so any prior experience with that tracker is helpful but not necessary. If you haven't already, have a look at the Android Tracker Setup guide before continuing.

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1.1. Demo App

If you would like to see the Tracker in action you can download our demonstration android app here. You will need to enable installation of applications from unknown sources.

Within the app you will simply need to supply an endpoint and hit start! The application will then send all types of events available to the tracker to this endpoint.

For a walkthrough go here.

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2 Initialization

Assuming you have completed the Android Tracker Setup for your project, you are now ready to initialize the Android Tracker.

2.1 Importing the module

Import the Android Tracker's classes into your Android code like so:

import com.snowplowanalytics.snowplow.tracker.*;

That's it - you are now ready to initialize a Tracker instance.

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2.2 Creating a Tracker

To instantiate a tracker in your code (can be global or local to the process being tracked) simply instantiate the Tracker interface with one of the following:

// Create an Emitter
Emitter e1 = new Emitter
        .EmitterBuilder("com.collector.acme", getContext())

// Make and return the Tracker object
Tracker t1 = new Tracker
        .TrackerBuilder(e1, "myNamespace", "myAppId")

This is the most basic Tracker creation possible. Note that getContext() is an Android global function. You can expand on this creation with the following builder options:

// Create an Emitter
Emitter e2 = new Emitter
        .EmitterBuilder("com.collector.acme", getContext())

// Create a Tracker with all options
Tracker t2 = new Tracker
        .TrackerBuilder(e2, "myNamespace", "myAppId")
        .base64(false) // Optional - defines if we use base64 encoding
        .platform(DevicePlatforms.Mobile) // Optional - defines what platform the event will report to be on
        .subject(new Subject.SubjectBuilder().build()) // Optional - a subject which contains values appended to every event

As you can see there is a fair amount of modularity to the Trackers creation.

The below are required arguments for the 'TrackerBuilder({{ ... }})' segment of the constructor:

Argument Name Description Required?
emitter The emitter which sends the events Yes
namespace The name of the tracker instance Yes
appId The application ID Yes

We also have several extra builder options:

Function Description Options Default
subject The subject that defines a user Subject, null null
platform The platform that the Tracker is running on DevicePlatforms.{{ Enum Option }} DevicePlatforms.Mobile
base64 Whether to enable Base64 encoding True, False True
level The level of logging to do LogLevel.{{ Enum Option}} LogLevel.OFF
2.3.1 emitter

The emitter to which the tracker will send events. See Emitters for more on emitter configuration.

2.3.2 subject

The user which the Tracker will track. This should be an instance of the Subject class. You don't need to set this during Tracker construction; you can use the Tracker.setSubject method afterwards. In fact, you don't need to create a subject at all. If you don't, though, your events won't contain user-specific data such as timezone and language.

2.3.3 namespace

If provided, the namespace argument will be attached to every event fired by the new tracker. This allows you to later identify which tracker fired which event if you have multiple trackers running.

2.3.4 appId

The appId argument lets you set the application ID to any string.

2.3.5 base64

By default, unstructured events and custom contexts are encoded into Base64 to ensure that no data is lost or corrupted. You can turn encoding on or off using the Boolean base64Encoded argument.

2.3.6 platform

The 'platform' allows you to pick from a list of allowed platforms which define what type of device/service the event is being sent from.

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2.3.7 Change the tracker's platform with setPlatform

You can change the platform by calling:

// OR
// OR
tracker.setPlatform(DevicePlatforms.{{ Valid Enum Option }})

There are several different DevicePlatforms options to choose from.

For a full list of supported platforms, please see the Snowplow Tracker Protocol.

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2.3.8 Change the tracker's subject with setSubject

You can change the subject by creating a new Subject object and then calling:


See Adding extra data: the Subject class for more information on the Subject.

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2.3.9 Change the tracker's emitter with setEmitter

You can change the emitter by creating a new Emitter object and then calling:


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3. Adding extra data: the Subject class

You may have additional information about your application's environment, current user and so on, which you want to send to Snowplow with each event. The Subject appended to the Tracker allows you to easily add information to each event that is sent from the Tracker.

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3.1 Subject setter functions

The Subject class has a set of set...() methods to attach extra data relating to the user to all tracked events:

Here are some examples:

Subject s1 = new Subject.SubjectBuilder().build();

s1.setUserID("Kevin Gleason");
s1.setScreenResolution(1920, 1080);

After that, you can add your Subject to your Tracker like so:

Tracker t1 = new Tracker
        .TrackerBuilder(emitter, "myNamespace", "myAppId")
        .subject(s1) // Include your subject here!

// Or you can set the subject after creation
// This will also override any currently set Subject object


To update the Trackers subject without changing the subject attached already you can use the following:

t1.getSubject().setUserId("Gleason Kevin"); // Because object references are passed by value in Java

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3.1.1 Set user ID with setUserId

You can set the user ID to any string:

setUserId(String userId)



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3.1.2 Set screen resolution with setScreenResolution

If your Java code has access to the device's screen resolution, then you can pass this in to Snowplow too:

setScreenResolution(int width, int height)

Both numbers should be positive integers; note the order is width followed by height. Example:

subj.setScreenResolution(1366, 768);

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3.1.3 Set viewport dimensions with setViewport

If your Java code has access to the viewport dimensions, then you can pass this in to Snowplow too:

setViewport(int width, int height)

Both numbers should be positive integers; note the order is width followed by height. Example:

subj.setViewport(300, 200);

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3.1.4 Set color depth with setColorDepth

If your Java code has access to the bit depth of the device's color palette for displaying images, then you can pass this in to Snowplow too:

setColorDepth(int depth)

The number should be a positive integer, measured in bits per pixel. Example:


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3.1.5 Set timezone with setTimezone

This method lets you pass a user's timezone in to Snowplow:

setTimezone(String timezone)

The timezone should be a string:


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3.1.6 Set the language with setLanguage

This method lets you pass a user's language in to Snowplow:

setLanguage(String language)

The language should be a string:


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3.1.7 setIpAddress

This method lets you pass a user's IP Address in to Snowplow:

setIpAddress(String ipAddress)

The IP address should be a string:


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3.1.8 setUseragent

This method lets you pass a useragent in to Snowplow:

setUseragent(String useragent)

The useragent should be a string:

subj.setUseragent("Agent Smith");

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3.1.9 setNetworkUserId

This method lets you pass a Network User ID in to Snowplow:

setNetworkUserId(String networkUserId)

The network user id should be a string:


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3.1.10 setDomainUserId

This method lets you pass a Domain User ID in to Snowplow:

setDomainUserId(String domainUserId)

The domain user id should be a string:


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3.2 Additional contexts sent by this tracker

This Tracker not only appends the generic subject information to each event; it will also attempt to gather more specific information about the mobile it is hosted on.

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3.2.1 mobile_context

The mobile_context is comprised of the following fields:

  • androidIdfa -> The host phones unique AdvertisingId
  • carrier -> The host phones phones network carrier
  • deviceModel -> The host phones phones model
  • deviceManufacturer -> The host phones phones manufacturer
  • osVersion -> The host phones phones operating system version
  • osType -> The host phones phones operating system type

To ensure you gather all of this information you will need to create your Subject with the following argument:

Subject subject = new Subject.SubjectBuilder().context(getContext()).build();

Note that getContext() is an Android global function. It is needed to grab information that is related to the client specifically.

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3.2.2 geolocation_context

The geolocation_context is comprised of the following fields:

  • latitude -> The host phones latitude measure
  • longitude -> The host phones longitude measure
  • altitude -> The host phones altitude measure
  • latitudeLongitudeAccuracy -> The host phones position accuracy
  • speed -> The host phones speed
  • bearing -> The host phones current bearing

To ensure you gather all of this information you will need to create your Subject with the following argument:

Subject subject = new Subject.SubjectBuilder().context(getContext()).build();

Note that getContext() is an Android global function.

You will also need to include the following in your AndroidManifest.xml file:

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

This will make the functions for checking these metrics available for the tracker to use.

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3.3 Getting the Android Idfa Code

The Android Idfa code is a unique identifier for google advertising. You can get this code using this library in two ways:

  1. Use the utility function available:
import com.snowplowanalytics.snowplow.tracker.utils.Util;

// Context is your application context object
String androidIdfa = Util.getAdvertisingId(context);

Please note that this function will only work when run from a different thread than the UI/Main thread of your application.

  1. Get it from the Subject class:

If you created a Tracker Subject with your application's context then the ID will have already been populated.

String androidIdfa = tracker.getSubject().getSubjectMobile().get("androidIdfa");

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4. Tracking specific events

Snowplow has been built to enable you to track a wide range of events that occur when users interact with your websites and apps. We are constantly growing the range of functions available in order to capture that data more richly.

Tracking methods supported by the Android Tracker at a glance:

Function *Description
trackScreenView() Track the user viewing a screen within the application
trackPageView() Track and record views of web pages.
trackEcommerceTransaction() Track an ecommerce transaction and its items
trackStructuredEvent() Track a Snowplow custom structured event
trackUnstructuredEvent() Track a Snowplow custom unstructured event

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4.1 Common

All events are tracked with specific methods on the tracker instance, of the form trackXXX(), where XXX is the name of the event to track.

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4.1.1 SelfDescribingJson

A SelfDescribingJson is used as a wrapper around either a TrackerPayload, another SelfDescribingJson or a Map object. After creating the object you want to wrap, you can create a SelfDescribingJson using the following:

// This is the Map we have created
Map<String, String> eventData = new HashMap<>();
eventData.put("Event", "Data")

// We wrap that map in a SelfDescribingJson before sending it
SelfDescribingJson json = new SelfDescribingJson("iglu:com.acme/example/jsonschema/1-0-0", eventData);

You can create a SelfDescribingJson with the following arguments:

Argument Description Required? Type
schema JsonSchema that describes the data Yes String
data Data that will be validated by the schema No Map<String, String>, Map<String, Object>, TrackerPayload, SelfDescribingJson

SelfDescribingJson is used for recording custom contexts and unstructured events.

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4.1.2 Custom contexts

In short, custom contexts let you add additional information about the circumstances surrounding an event in the form of a Map object. Each tracking method accepts an additional optional contexts parameter after all the parameters specific to that method:

t1.trackPageView(String pageUrl, String pageTitle, String referrer);
t1.trackPageView(String pageUrl, String pageTitle, String referrer, List<SelfDescribingJson> context);
t1.trackPageView(String pageUrl, String pageTitle, String referrer, double timestamp);
t1.trackPageView(String pageUrl, String pageTitle, String referrer, List<SelfDescribingJson> context, double timestamp);

The context argument should consist of a List of SelfDescribingJson representing an array of one or more contexts. The format of each individual context element is the same as for an unstructured event.

If a visitor arrives on a page advertising a movie, the context dictionary might look like this:

  "schema": "iglu:com.acme_company/movie_poster/jsonschema/2.1.1",
  "data": {
    "movie_name": "Solaris",
    "poster_country": "JP",
    "poster_year": "1978"

To construct this as a SelfDescribingJson:

// Create a Map of the data you want to include...
Map<String, String> dataMap = new HashMap<>();
dataMap.put("movie_name", "solaris");
dataMap.put("poster_country", "JP");
dataMap.put("poster_year", "1978");

// Now create your SelfDescribingJson object...
SelfDescribingJson context1 = new SelfDescribingJson("iglu:com.acme/movie_poster/jsonschema/2.1.1", dataMap);

// Now add this JSON into a list of SelfDescribingJsons...
List<SelfDescribingJson> contexts = new ArrayList<>();

Note that even if there is only one custom context attached to the event, it still needs to be placed in an array.

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4.1.3 Timestamp override

In all the trackers, we offer a way to override the timestamp if you want the event to show as tracked at a specific time. If you don't, we create a timestamp while the event is being tracked.

Here are some example:

t1.trackPageView("", "Example Page", "");
t1.trackPageView("", "Example Page", "", contexts);
t1.trackPageView("", "Example Page", "", contexts, 1423583655000);
t1.trackPageView("", "Example Page", "", 1423583655000);

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4.2 Track screen views with trackScreenView()

Use trackScreenView() to track a user viewing a screen (or equivalent) within your app. Arguments are:

Argument Description Required? Type
name Human-readable name for this screen No String
id Unique identifier for this screen No String
context Custom context for the event No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long


t1.trackScreenView("HUD > Save Game", "screen23");
t1.trackScreenView("HUD > Save Game", contextList, 1423583655000);

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4.3 Track pageviews with trackPageView()

You can use trackPageView() to track a user viewing a web page within your app.

Arguments are:

Argument Description Required? Type
page_url The URL of the page Yes String
page_title The title of the page Yes String
referrer The address which linked to the page Yes String
context Custom context for the event No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long


t1.trackPageView("", "example", "", contextList);
t1.trackPageView("", "example", "");

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4.4 Track ecommerce transactions with trackEcommerceTransaction()

Use trackEcommerceTransaction() to track an ecommerce transaction.


Argument Description Required? Type
order_id ID of the eCommerce transaction Yes String
total_value Total transaction value Yes Double
affiliation Transaction affiliation Yes String
tax_value Transaction tax value Yes Double
shipping Delivery cost charged Yes Double
city Delivery address city Yes String
state Delivery address state Yes String
country Delivery address country Yes String
currency Transaction currency Yes String
items Items in the transaction Yes List<TransactionItem>
context Custom context for the event No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long

The items argument is a List of individual TransactionItem elements representing the items in the e-commerce transaction. Note that trackEcommerceTransaction fires multiple events: one transaction event for the transaction as a whole, and one transaction item event for each element of the items List. Each transaction item event will have the same timestamp, order_id, and currency as the main transaction event.

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4.4.1 TransactionItem

To instantiate a TransactionItem in your code, simply use the following constructor signature:

TransactionItem item = new TransactionItem("item_id", "item_sku", 1.00, 1, "item_name", "item_category", "currency", custom_contexts, 1424080355000);

These are the fields that can appear as elements in each TransactionItem element of the transaction item's List:

Field Description Required? Type
item_id Item ID Yes String
sku Item SKU No String
price Item price No double
quantity Item quantity No int
name Item name No String
category Item category No String
currency Item currency No String
context Item context No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long

Example of tracking a transaction containing two items:

// Create some Transaction Items
TransactionItem item1 = new TransactionItem("item_id_1", "item_sku_1", 1.00, 1, "item_name", "item_category", "currency");
TransactionItem item2 = new TransactionItem("item_id_2", "item_sku_2", 1.00, 1, "item_name", "item_category", "currency");

// Add these items to a List
List<TransactionItem> items = new ArrayList<>();

// Now Track the Transaction by using this list of items as an argument
t1.trackEcommerceTransaction("6a8078be", 300, "my_affiliate", 30, 10, "Boston", "Massachusetts", "USA", "USD", items);

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4.5 Track structured events with trackStructuredEvent()

Use trackStructuredEvent() to track a custom event happening in your app which fits the Google Analytics-style structure of having up to five fields (with only the first two required):

Argument Description Required? Type
category The grouping of structured events which this action belongs to Yes String
action Defines the type of user interaction which this event involves Yes String
label A string to provide additional dimensions to the event data No String
property A string describing the object or the action performed on it No String
value A value to provide numerical data about the event No int
context Custom context for the event No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long


t1.trackStructuredEvent("shop", "add-to-basket", "Add To Basket", "pcs", 2);
t1.trackStructuredEvent("shop", "add-to-basket", "Add To Basket", "pcs", 2, 1423653510000);

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4.6 Track unstructured events with trackUnstructuredEvent()

Custom unstructured events are a flexible tool that enable Snowplow users to define their own event types and send them into Snowplow.

When a user sends in a custom unstructured event, they do so as a JSON of name-value properties, that conforms to a JSON schema defined for the event earlier.

Use trackUnstructuredEvent() to track a custom event which consists of a name and an unstructured set of properties. This is useful when:

  • You want to track event types which are proprietary/specific to your business (i.e. not already part of Snowplow), or
  • You want to track events which have unpredictable or frequently changing properties

The arguments are as follows:

Argument Description Required? Type
eventData The properties of the event Yes SelfDescribingJson
context Custom context for the event No List<SelfDescribingJson>
timestamp Optional timestamp for the event No Long

Example event json to track:

  "schema": "iglu:com.acme/save_game/jsonschema/1-0-0",
  "data": {
    "levelName": "Barrels o' Fun",
    "levelIndex": 23

How to set it up?

// Create a Map of your event data
Map<String, Object> eventMap = new HashMap<>();
eventMap.put("levelName", "Barrels o' Fun")
eventMap.put("levelIndex", 23);

// Create your event data
SelfDescribingJson eventData = new SelfDescribingJson("iglu:com.acme/save_game/jsonschema/1-0-0", eventMap);

// Track your event with your custom event data
t1.trackUnstructuredEvent(eventData, contextList);

For more on JSON schema, see the blog post.

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5. Sending event: Emitter

Events are sent using an Emitter class. You can initialize a class with a collector endpoint URL with various options to choose how these events should be sent. Here are the Emitter interfaces that can be used:

Emitter e2 = new Emitter
        .EmitterBuilder("com.collector.acme", Context context) // Required
        .method(HttpMethod.GET) // Optional - Defines how we send the request
        .option(BufferOption.Single) // Optional - Defines how many events we bundle in a POST
        .security(EmitterSecurity.HTTPS) // Optional - Defines what protocol used to send events
        .callback(new EmitterCallback() {...})

The Context is used for caching events in a SQLite database in order to avoid losing events to network related issues.

Don't confuse the Android context with Snowplow's own custom contexts - they are completely separate things.

The below are required arguments for the 'EmitterBuilder({{ ... }})' segment of the constructor:

Argument Name Description Required?
URI The collector endpoint URI events will be sent to Yes
context Used to use to open or create an SQLite database Yes

We also have several extra builder options such as:

Function Description Options Default
method The request method to use HttpMethod.GET, .POST HttpMethod.POST
option The amount of events sent in a POST request BufferOption.{{ Enum Option}} BufferOption.DefaultGroup
security Whether to send over HTTP or HTTPS RequestSecurity.HTTP, .HTTPS RequestSecurity.HTTP
callback A callback to output successes and failures new RequestCallback{ ... } null
tick The time between emitter ticks Any positive int 5
sendLimit The maximum amount of events to get from the DB Any positive int 250
emptyLimit The amount of times the emitter can be empty Any positive int 5
byteLimitGet The maximum amount of bytes to send in a GET Any positive int 40000
byteLimitPost The maximum amount of bytes to send in a POST Any positive int 40000

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5.1 How the Emitter works

The Emitter is configured and setup to run as a background process so it never blocks on the Main Thread or on the UI Thread of the device it is on.

The current Emitter flow goes as follows:

  1. Emitter is created
  2. Emitter will check if it has access to the internet
  3. If it is it will begin a recurring check for events to send to the configured collector
    • This defaults to every 5 seconds
  4. If there are events in the SQlite database the emitter will grab up to 250 (default) events from the database and begin sending.
  5. Once it has finished sending it will again check for events
  6. If there are no events to be sent 5 (default) times in a row, it will shut itself down
  7. On receiving a new event the Emitter checks again if it is online and will then begin sending again
  8. If there are only errors in sending, the events will not be deleted from the database and the emitter will then be shutdown
    • If there are some successes it will not shutdown.

5.2 Using a buffer

A buffer is used to group events together in bulk before sending them. This is especially handy to reduce network usage. By default, the Emitter buffers up to 10 events together before sending them; only available if you are using POST as your request type.

e1.setBufferOption(BufferOption.Single); // 1
// OR
e1.setBufferOption(BufferOption.DefaultGroup); // 10
// OR For heavier event sending...
e1.setBufferOption(BufferOption.HeavyGroup); // 25

Here are all the posibile options that you can use:

Option Description
Single Events are sent individually
DefaultGroup Sends events in groups of 10 events or less
HeavyGroup Sends events in groups of 25 events or less

Buffer options will only ever influence how POST request are sent however. All GET requests will be sent individually.

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5.3 Choosing the HTTP method

Snowplow supports receiving events via both GET and POST requests. In a GET request, each event is sent in individual request. With POST requests, events are bundled together in one request.

You can set the HTTP method in the Emitter constructor:

Emitter e2 = new Emitter
        .EmitterBuilder("com.collector.acme", Context context)

Here are all the posibile options that you can use:

Option Description
GET Sends events as GET requests
POST Sends events as POST requests

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5.4 Emitter callback

If an event fails to send because of a network issue, you can choose to handle the failure case with a callback class to react accordingly. The callback class needs to implement the EmitterCallback interface in order to do so. Here is a sample bit of code to show how it could work:

RequestCallback callback = new RequestCallback() {
  public void onSuccess(int successCount) {
    Log.d("Tracker", "Buffer length for POST/GET:" + successCount);
  public void onFailure(int successCount, int failureCount) {
    Log.d("Tracker", "Failures: " + failureCount + "; Successes: " + successCount);

Emitter emitter = new Emitter
        .EmitterBuilder("com.collector.acme", Context context)

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6. Logging

Logging in the Tracker is done using our own Logger class: '/utils/'. All logging is actioned based on what LogLevel was set in the Tracker creation. This level can be configured to VERBOSE, DEBUG, ERROR or OFF. By default logging is not enabled.

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