Android (0.5.0)

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Tracker

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.

NOTE: The Tracker should only ever be setup as a singleton object. Due to the way it stores and reads information and the creation of persistent background services, creating more than one Tracker can cause a plethora of race conditions.

1. Double (or more) sending of events.
2. Constant session expiration (as old Tracker services continually fail to see any new events being created).

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.

1.2. Client Sessions

To activate client sessionization please enter the following builder arguments to your tracker:

Tracker tracker = new Tracker.TrackerBuilder( ... )
    .sessionContext(true)     // To use the session context
    .sessionCheckInterval(10) // Checks every 10 seconds (default is 15)
    .foregroundTimeout(300)   // Timeout after 5 minutes (default is 10)
    .backgroundTimeout(120)   // Timeout after 2 minutes (default is 5)
    .build();

Once sessionization has been turned on several things will begin to happen:

• A client_session context will be appended to each event that is sent
• A polling check will be started to check whether or not the session has timed out
  • You can configure how often to check with the sessionCheckInterval method
  • If your app is in the foreground and no events have been sent for the foregroundTimeout period, the session will be updated and a new session started
  • There is a separate timeout if your application is detected to be in the background
• Each time the session information is updated it is stored locally in a private file which should persist for the life of the application
• Each time an event is sent from the Tracker, both timeouts for the session are reset
• Session information will survive for the life of the application, i.e. until it is uninstalled from the Android device.

An important note here is that the tracker does not automatically detect if the application is in the background or not from a library standpoint. You will have to update your applications onPause() and onResume() functions to manually flag this change. The following samples can be copied into an application activity to set the background state of the application for the session checker:

@Override
protected void onPause() {
    super.onPause();
    tracker.getSession().setIsBackground(true);
}

@Override
protected void onResume() {
    super.onResume();
    tracker.getSession().setIsBackground(false);
}

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.

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())
        .build();

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

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())
        .build();

// Create a Tracker with all options
Tracker t2 = new Tracker
        .TrackerBuilder(e2, "myNamespace", "myAppId", getContext())
        .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
        .build();

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
context	The application context	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
sessionContext	Whether to enable sessionization	True, False	False
foregroundTimeout	The session foreground timeout	Any valid Long	600
backgroundTimeout	The session background timeout	Any valid Long	300
sessionCheckInterval	The session check interval	Any valid Long	15
threadCount	The amount of threads to use	Any valid Integer	10 threads
timeUnit	The TimeUnit that time measurements are in	TimeUnit.{{ Enum Option }}	TimeUnit.SECONDS

2.2.1 Constructor Options Explained

Required

• emitter : The pre created Emitter object which is required for all sending and storing of events by the Tracker. See Emitters for information.
• namespace : The name of this Tracker instance to include with events sent to the collector.
• appId : The ID of this application to include with events sent to the collector.
• context : The Android Application context object.

Event Decoration

• subject : An optional Subject object which will add extra decoration to events sent from the Tracker.
• platform : The platform that the Tracker is running on (defaults to MOBILE)
• base64 : Whether to encode unstructured events and custom contexts in base64 formatting.

Session Parameters

• sessionContext : Needs to be set to True if you wish to activate any of the Trackers Sessionization functionality.
• foregroundTimeout : The amount of time that needs to elapse without any events being tracked before the session is incremented (while application is in the foreground).
• backgroundTimeout : The amount of time that needs to elapse without any events being tracked before the session is incremented (while application is in the background).
• sessionCheckInterval : How often the Tracker queries the session object to see if it needs to be incremented. It is currently set to 15 seconds.
• timeUnit : The unit of time that the previous three options are computed on. By default it is in SECONDS, as such to set a sessionCheckInterval of 2 minutes you would need to put in 120 for that option. Or you could change the timeUnit to be MINUTES and put a 2 instead.

Functional Settings

• threadCount : The amount of threads that the Tracker will have available to it to process information in. By default we use 10 Threads, however it is recommended to figure out the optimal amount of Threads on a device by device basis as more Threads will have a direct correlation with performance.
• level : The amount of logging done by the Tracker.

2.3 Tracker Functions

2.3.1 getEmitter

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

2.3.2 getSubject

Returns the user which the Tracker will track. This must 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 getNamespace

Returns the namespace argument 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 getAppId

Returns the appId argument that you passed in Tracker construction.

2.3.5 getBase64Encoded

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 builder option.

2.3.6 getPlatform

Returns the 'platform' that was set in Tracker construction, the builder allows you to pick from a list of allowed platforms which define what type of device/service the event is being sent from.

2.3.7 getSession

Returns the session object created for the Tracker (if sessionContext was enabled).

2.3.8 getDataCollection

Returns the state of data collection in the Tracker; either True or False.

2.3.9 getLogLevel

Returns the LogLevel being used by the Tracker.

2.3.10 getThreadCount

Returns the amount of threads that the tracker is consuming.

2.3.11 getTrackerVersion

Returns this Trackers version as a String.

2.3.12 Change the tracker's platform with setPlatform

You can change the platform by calling:

tracker.setPlatform(DevicePlatforms.Mobile);
// OR
tracker.setPlatform(DevicePlatforms.Desktop);
// 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.

2.3.13 Change the tracker's subject with setSubject

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

tracker.setSubject(newSubject);

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

2.3.14 Change the tracker's emitter with setEmitter

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

tracker.setEmitter(newEmitter);

2.4 Extra Tracker Functions

These are extra functions for controlling the Tracker. The Tracker is designed to be run without ever using any of these functions however they are there for any special use cases where you need to shutdown or otherwise control the Tracker.

For example if you wish to artificially extend the time a session is active you can simply pauseSessionChecking for an undetermined amount of time. To resume automatic session checking and updating simply run resumeSessionChecking.

2.4.1 resumeSessionChecking

This function resumes a polling session checker service. This will query the Trackers session object at pre-configured intervals to see whether or not the session needs to be updated if it has not been accessed within a certain amount of time.

This function is started if the argument to .sessionContext is True, and will only ever be able to run if this argument is True.

tracker.resumeSessionChecking();

2.4.2 pauseSessionChecking

This functions stops the session checker from running. Essentially preventing the current session from ever timing out. Please note that if the application is restarted this paused state will not persist and checking will begin again.

tracker.pauseSessionChecking();

2.4.3 resumeEventTracking

If event tracking has been switched off this will reinstate the Tracker back to full operation. This means that:

• Events will start being stored in the database again.
• Events will be sent to the collector.
• Session checking will begin to occur again (if enabled)

tracker.resumeEventTracking();

2.4.4 pauseEventTracking

If event tracking is switched on (it is by default), then the Tracker will have all event tracking paused. What this means is that:

• No events will be stored in the database or tracked at all.
• No events will be sent to the collector.
• No session checks will occur.

Essentially the entire Tracker will halt operation until event tracking is turned back on.

tracker.pauseEventTracking();

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.

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:

• setUserId
• setScreenResolution
• setViewport
• setColorDepth
• setTimezone
• setLanguage
• setIpAddress
• setUseragent
• setNetworkUserId
• setDomainUserId
• setAdvertisingID
• setCarrier
• setLocation
• setDefaultScreenResolution

Here are some examples:

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

s1.setUserID("Kevin Gleason");
s1.setLanguage("en-gb");
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!
        .build();

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

t1.setSubject(s1);

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

3.1.1 Set user ID with setUserId

You can set the user ID to any string:

setUserId(String userId)

Example:

subj.setUserId("alexd");

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);

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);

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:

subj.setColorDepth(32);

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:

subj.setTimezone("Europe/London");

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:

subj.setLanguage("en");

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:

subj.setIpAddress("127.0.0.1");

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");

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:

subj.setNetworkUserId("network-id");

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:

subj.setDomainUserId("domain-id");

3.1.11 setAdvertisingID

This method lets you set the Advertising ID

setAdvertisingID(Context context)

You will need to pass in the application's context as a parameter.

subj.setAdvertisingID(context);

3.1.12 setCarrier

This method lets you set the mobile carrier.

setCarrier(Context context)

You will need to pass in the application's context as a parameter.

subj.setCarrier(context);

3.1.13 setLocation

This method lets you set the mobile location.

setLocation(Context context)

You will need to pass in the application's context as a parameter.

subj.setLocation(context);

3.1.14 setDefaultScreenResolution

This method lets you set the default screen resolution using the application context.

setDefaultScreenResolution(Context context)

You will need to pass in the application's context as a parameter.

subj.setDefaultScreenResolution(context);

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.

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.

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.

3.3 Getting the Android Idfa Code

NOTE: For this code to be available you must include the following library dependency:

• `compile 'com.google.android.gms:play-services-analytics:7.5.0'

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");

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
track(ScreenView event)	Track the user viewing a screen within the application
track(PageView event)	Track and record views of web pages
track(EcommerceTransaction event)	Track an ecommerce transaction and its items
track(Structured event)	Track a Snowplow custom structured event
track(Unstructured event)	Track a Snowplow custom unstructured event
track(TimingWithCategory event)	Track a Timing with Category event

4.1 Common

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

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.

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:

t1.track(PageView.builder().( ... ).customContext(List<SelfDescribingJson> context).build());

The customContext 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<>();
contexts.add(context1);

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

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 is an example:

t1.track(PageView.builder().( ... ).timestamp(1423583655000).build());

4.2 Track screen views with track(ScreenView event)

Use track(ScreenView event) to track a user viewing a screen (or equivalent) within your app. You must use either name or id. Arguments are:

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

Examples:

t1.track(ScreenView.builder()
    .name("HUD > Save Game")
    .id("screen23")
    .build());

t1.track(ScreenView.builder()
    .name("HUD > Save Game")
    .id("screen23")
    .customContext(contextList)
    .timestamp(1423583655000)
    .eventId("uid-1")
    .build());

4.3 Track pageviews with track(PageView event)

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

Arguments are:

Argument	Description	Required?	Type
pageUrl	The URL of the page	Yes	String
pageTitle	The title of the page	No	String
referrer	The address which linked to the page	No	String
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

Examples:

t1.track(PageView.builder()
    .pageUrl("www.example.com")
    .pageTitle("example")
    .referrer("www.referrer.com")
    .build());

t1.track(PageView.builder()
    .pageUrl("www.example.com")
    .pageTitle("example")
    .referrer("www.referrer.com")
    .customContext(contextList)
    .timestamp(1423583655000)
    .eventId("uid-1")
    .build());

4.4 Track ecommerce transactions with track(EcommerceTransaction event)

Use track(EcommerceTransaction event) to track an ecommerce transaction.

Arguments:

Argument	Description	Required?	Type
orderId	ID of the eCommerce transaction	Yes	String
totalValue	Total transaction value	Yes	Double
affiliation	Transaction affiliation	No	String
taxValue	Transaction tax value	No	Double
shipping	Delivery cost charged	No	Double
city	Delivery address city	No	String
state	Delivery address state	No	String
country	Delivery address country	No	String
currency	Transaction currency	No	String
items	Items in the transaction	Yes	List<EcommerceTransactionItem>
items	Items in the transaction	Yes	EcommerceTransactionItem...
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

The items argument is a List of individual EcommerceTransactionItem elements representing the items in the e-commerce transaction or it can be a varargs argument of many individual items. Note that track(EcommerceTransaction event) 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.

4.4.1 EcommerceTransactionItem

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

EcommerceTransactionItem item = EcommerceTransactionItem.builder()
    .itemId("item_id")
    .sku("item_sku")
    .price(1.00)
    .quantity(1)
    .name("item_name")
    .category("item_category")
    .currency("currency")
    .build();

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

Field	Description	Required?	Type
itemId	Item ID	Yes	String
sku	Item SKU	Yes	String
price	Item price	Yes	Double
quantity	Item quantity	Yes	Integer
name	Item name	No	String
category	Item category	No	String
currency	Item currency	No	String
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

Example of tracking a transaction containing two items:

// Create some Transaction Items
EcommerceTransactionItem item1 = EcommerceTransactionItem.builder()
    .itemId("item_id_1")
    .sku("item_sku_1")
    .price(1.00)
    .quantity(1)
    .name("item_name")
    .category("item_category")
    .currency("currency")
    .build();

EcommerceTransactionItem item2 = EcommerceTransactionItem.builder()
    .itemId("item_id_2")
    .sku("item_sku_2")
    .price(1.00)
    .quantity(1)
    .name("item_name")
    .category("item_category")
    .currency("currency")
    .build();

// Add these items to a List
List<EcommerceTransactionItem> items = new ArrayList<>();
items.add(item1);
items.add(item2);

// Now Track the Transaction by using this list of items as an argument
tracker.track(EcommerceTransaction.builder()
    .orderId("6a8078be")
    .totalValue(300.00)
    .affiliation("my_affiliate")
    .taxValue(30.00)
    .shipping(10.00)
    .city("Boston")
    .state("Massachusetts")
    .country("USA")
    .currency("USD")
    .items(items)
    .build());

// Or include the items as varargs in the items section
tracker.track(EcommerceTransaction.builder()
    .orderId("6a8078be")
    .totalValue(300.00)
    .affiliation("my_affiliate")
    .taxValue(30.00)
    .shipping(10.00)
    .city("Boston")
    .state("Massachusetts")
    .country("USA")
    .currency("USD")
    .items(item1, item2)
    .build());

4.5 Track structured events with track(Structured event)

Use track(Structured event) 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	Double
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

Examples:

t1.track(Structured.builder()
    .category("shop")
    .action("add-to-basket")
    .label("Add To Basket")
    .property("pcs")
    .value(2.00)
    .build());

t1.track(Structured.builder()
    .category("shop")
    .action("add-to-basket")
    .label("Add To Basket")
    .property("pcs")
    .value(2.00)
    .customContext(contextList)
    .timestamp(1423583655000)
    .eventId("uid-1")
    .build());

4.6 Track unstructured events with track(Unstructured event)

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 track(Unstructured event) 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
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

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.track(Unstructured.builder()
    .eventData(eventData)
    .build();

// OR

t1.track(Unstructured.builder()
    .eventData(eventData)
    .customContext(contextList)
    .timestamp(1423583655000)
    .eventId("uid-1")
    .build();

For more on JSON schema, see the blog post.

4.7 Track timing events with track(TimingWithCategory event)

Use track(TimingWithCategory event) to track an event related to a custom timing.

Argument	Description	Required?	Type
category	The category of the timed event	Yes	String
label	The label of the timed event	No	String
timing	The timing measurement in milliseconds	Yes	Integer
variable	The name of the timed event	Yes	String
customContext	Optional custom context	No	List<SelfDescribingJson>
timestamp	Optional timestamp	No	Long
eventId	Optional custom event id	No	String

Examples:

t1.track(TimingWithCategory.builder()
    .category("category")
    .variable("variable")
    .timing(1)
    .label("label")
    .build());

t1.track(TimingWithCategory.builder()
    .category("category")
    .variable("variable")
    .timing(1)
    .label("label")
    .customContext(contextList)
    .timestamp(1423583655000)
    .eventId("uid-1")
    .build());

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(RequestSecurity.HTTPS) // Optional - Defines what protocol used to send events
        .callback(new EmitterCallback() {...})
        .build();

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
timeUnit	The TimeUnit that time measurements are in	TimeUnit.{{ Enum Option }}	TimeUnit.SECONDS

5.1 Emitter Constructor Explained

Required

• uri : The collector endpoint that all events will be sent to. Needs to be the raw path in the sense that you will not include any http:// or https:// with the address. Rather something like: www.fake.io in place of http://www.fake.io. The http security setting is configured in a seperate option.
• context : The Android Application context object.

Sending

• method : Whether to send requests via GET or POST; essentially whether to send each event individually or to send many events together in a POST. The default POST setting is recommended as it has huge performance gains over sending individually as a GET.
• option : How many events can be parcelled together in a POST, this can be increased to a maximum of 25 per event. If you require larger volumes please raise a ticket to have this limit increased!
• security : Whether to send events via HTTP or HTTPS.
• callback : A custom callback method that will be called after each emitter send loop, currently the only variables included are the count of successfully and unsuccessfully sent events.
• byteLimitGet : Allows you to set an upper limit for the maximal size of a single GET request. Meaning that if an event exceeds this size we will attempt to send it but will then delete it from the database regardless of success to send.
• byteLimitPost : Allows you to set an upper limit for the maximal size of a single POST request. Meaning that if an event exceeds this size we will attempt to send it but will then delete it from the database regardless of success to send.

Functional Settings

• tick : The interval at which the emitter will check for more events.
• timeUnit : The timeunit that the aforementioned tick is measured in. By default we measure this in seconds.
• sendLimit : The upper limit of events that can be grabbed from the database per sending session, this in place to avoid consuming overt amounts of memory in case of huge event ingress. On weaker devices this can be tuned down to and on beefier devices can be greatly increased.
• emptyLimit : The amount of times that the emitter is allowed to fail a check before it will release its Thread back to the pool.

5.2 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.

5.3 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.

5.4 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)
        .method(HttpMethod.GET)
        .build();

Here are all the posibile options that you can use:

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

5.5 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() {
  @Override
  public void onSuccess(int successCount) {
    Log.d("Tracker", "Buffer length for POST/GET:" + successCount);
  }
  @Override
  public void onFailure(int successCount, int failureCount) {
    Log.d("Tracker", "Failures: " + failureCount + "; Successes: " + successCount);
  }
});

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

5.6 Emitter Flush

If you want to ensure that there are no events left in the local database for sending simply run the emitter flush() function like so:

tracker.getEmitter().flush();

This will attempt to start the emitter process; however it will fail if the emitter is already running or if the application is offline.

6. Logging

Logging in the Tracker is done using our own Logger class: '/utils/Logger.java'. 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.

---

Integration

1. Classic Tracker

You will need to have imported the following library into your project:

dependencies {
    ...
    // Snowplow Android Tracker Classic
    compile 'com.snowplowanalytics:snowplow-android-tracker-classic:0.5.4'
}

Example class to return an Android Classic Tracker:

import com.snowplowanalytics.snowplow.tracker.*;
import android.content.Context;

public class TrackerBuilderClassic {

    public static Tracker getClassicTracker(Context context) {
        Emitter emitter = getClassicEmitter(context);
        Subject subject = getSubject(context);  // Optional

        return new Tracker
            .TrackerBuilder(emitter, "your-namespace", "your-appid", context,
                com.snowplowanalytics.snowplow.tracker.classic.Tracker.class)
            .subject(subject) // Optional
            .build();
    }

    private static Emitter getClassicEmitter(Context context) {
        return new Emitter
            .EmitterBuilder("notarealuri.fake.io", context,
                com.snowplowanalytics.snowplow.tracker.classic.Emitter.class)
            .build();
    }

    private static Subject getSubject(Context context) {
        return new Subject
            .SubjectBuilder()
            .context(context)
            .build();
    }
}

2. RxJava tracker

You will need to have imported the following library into your project:

dependencies {
    ...
    // Snowplow Android Tracker Rx
    compile 'com.snowplowanalytics:snowplow-android-tracker-rx:0.5.4'
}

Example class to return an Android RxJava Tracker:

import com.snowplowanalytics.snowplow.tracker.*;
import android.content.Context;

public class TrackerBuilderRx {

    public static Tracker getRxTracker(Context context) {
        Emitter emitter = getRxEmitter(context);
        Subject subject = getSubject(context); // Optional

        return new Tracker
            .TrackerBuilder(emitter, "your-namespace", "your-appid", context,
                com.snowplowanalytics.snowplow.tracker.rx.Tracker.class)
            .subject(subject) // Optional
            .build();
    }

    private static Emitter getRxEmitter(Context context) {
        return new Emitter
            .EmitterBuilder("notarealuri.fake.io", context,
                com.snowplowanalytics.snowplow.tracker.rx.Emitter.class)
            .build();
    }

    private static Subject getSubject(Context context) {
        return new Subject
            .SubjectBuilder()
            .context(context)
            .build();
    }
}

3. Tracking Events

Once you have successfully built your Tracker object you can track events with calls like the following:

Tracker tracker = getClassicTracker(context);
tracker.track(ScreenView.builder().name("screenName").id("screenId").build());

For an outline of all available tracking combinations have a look here.

4. Application Focus

The Tracker Session object can be tuned to timeout in foreground and background scenarios, but you are required to tell us when your application is in these states. Unfortunately it is not possible to do so from a library standpoint.

The current implementation we are using is to override the onPause() and onResume() functions of an application activity to notify the session when we change states.

@Override
protected void onPause() {
    super.onPause();
    tracker.getSession().setIsBackground(true);
}

@Override
protected void onResume() {
    super.onResume();
    tracker.getSession().setIsBackground(false);
}

---

Testing locally

1. Testing Locally

To test the Android Tracker locally we use a combination of two softwares: Mountebank and Ngrok.

Mountebank provides a local webserver which we can apply imposters to run on different ports. An imposter in this context is just a mock which, for our purposes, does some light validation to ensure that the event it receives is indeed a valid Snowplow Event. This is the imposter that we use for validating our events.

We then get Ngrok to listen on the same port as the imposter port. This provides two things:

• A clean easy to use Web Interface with details about each event.
  • Found at http://localhost:4040/
• An endpoint that you can send to from anywhere.

When you visit the Ngrok Web Interface you will see the tunnel URL that you can use to send events to.

To actually set this up you will need to follow these steps:

 host$ git clone https://github.com/snowplow/snowplow-android-tracker.git
 host$ cd snowplow-android-tracker
 host$ vagrant up && vagrant ssh
guest$ cd /vagrant
guest$ chmod +x ./testing/setup.bash
guest$ ./testing/setup.bash

The setup.bash script starts Mountebank and starts the imposter we want and then starts Ngrok listening on the imposter port.

Once you have it running you can supply the tunnel URL for all logging of events until you are ready to switch to a collector!

2. Common Issues

This section will detail how to handle common problems with running the local testing setup.

2.1 Port Conflicts

If you are already using ports 2525 or 4040 your vagrant up will fail. Easiest way to resolve this is to stop any services running on these ports and then attempt to vagrant up again.

However if this is not an option you will need to edit the Vagrantfile in the root of the project:

config.vm.network "forwarded_port", guest: 4040, host: 4040 ## Change the host to something free
config.vm.network "forwarded_port", guest: 2525, host: 2525 ## Change the host to something free

2.2 Sending failures

If you have successfully started Ngrok and you have an endpoint but your events are not getting there chances are that Mountebank as failed to start properly.

To resolve:

guest$ curl -X DELETE http://localhost:2525/imposters/4545
guest$ curl -i -X POST -H 'Content-Type: application/json' -d@/vagrant/testing/imposter.json http://localhost:2525/imposters

This will delete the imposter and create a new one in its place.

If you you cannot get to the Ngrok Web Interface at all the best way to resolve is the following:

host$ cd snowplow-android-tracker
host$ vagrant halt
host$ vagrant up && vagrant ssh
guest$ cd /vagrant
guest$ ./testing/setup.bash

This simply stops the VM and restarts it.