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API for Acquisition Attribution of Web Apps

Author: Alex Kyereboah

Status of this Document

This document is a starting point for engaging the community and standards bodies in developing collaborative solutions fit for standardization. As the solutions to problems described in this document progress along the standards-track, we will retain this document as an archive and use this section to keep the community up-to-date with the most current standards venue and content location of future work and discussions.

Introduction

One of the major issues blocking the adoption of store platform advertisements is the lack of support for third-party (3P) attribution for Progressive Web Apps (PWAs). While attribution and acquisition information may look slightly different based on platform, PWAs lack this capability across all Store platforms (Microsoft Store, Google Play Store, Apple App Store). On Windows, this limitation prevents PWAs published in the Microsoft Store from obtaining the Campaign ID which identifies the ad campaign source of app acquisition. While Universal Windows Platform (UWP) apps can access this information through a WinRT API, the absence of similar functionality for PWAs poses a gap between native applications and PWAs. We aim to not only bridge this gap, but to enable similar functionality surrounding attribution for browser-installed web applications through the introduction of the Acquisition Info API.

Goals

  1. Provide a web API around 3P acquisition attribution for PWAs acquired through an app store or directly from the browser.

Non-Goals

  1. Define how a UA can retrieve acquisition information from every platform-specific Store.

Store-install Scenario (Windows)

A web app developer has submitted their app to the Microsoft Store, and they have created ad campaigns to promote their app. When a user sees and clicks on an advertisement that leads them to acquire the web app from the Store, the ad Campaign ID associated with the advertisement is recorded by the Store, and associated with the user's app entitlement. On any given launch of the Store-acquired web app, the web app developer can call the JavaScript API to request the acquisition information from the Store in order to retrieve the Campaign ID associated with that user/app acquisition. The web app developer will then be able to use this information to help determine which ad campaigns were most effective to best inform their future ad investment decisions.

Proposed Solution

The Acquisition Info API introduces the navigator.acquisitionInfoProvider attribute which allows developers to access a promise method that can return acquisition information for installed web apps. The API will be undefined when run as a normal tab in the browser (which explicity excludes support for the browser display mode). To obtain a valid value, the site needs to run as an installed web app. Browser extensions are not eligible to call this API.

The current shape of acquisition information

Currently, there are extensive solutions across multiple platforms for obtaining acquisition information in native applications beyond the WinRT API solution for Windows platform. The Google Play Store has the Play Install Referrer API to retrieve referral content from Google Play such as referrer URL, while the Apple App Store has the Apple Ads Attribution API that provides payloads with information such as campaign ID. However, all of these solutions are only available for use by native applications and there exists no equivalent for web apps. The Acquisition Info API aims to continue efforts to close the gap between native apps and web apps by providing that missing functionality.

Accessing the provider as an attribute

navigator.acquisitionInfoProvider accesses the acquisition info provider attribute of navigator, which provides access to the getDetails() method that surfaces various acquisition details, including the Campaign ID. There is no need for a parameter input when calling this method, as the user agent (UA) is expected to derive application context through the UA or store platform user account.

// Detecting if the API is supported in this context.
if (navigator.acquisitionInfoProvider) {
  try {
    let details = await navigator.acquisitionInfoProvider.getDetails();
    // App may log results here for backend attribution purposes
    console.log("Install source was: ", details.installSource);
    consle.log("From campaign: ", details.campaignId);
    // Use the returned dictionary here.
    ...
  } catch (error) {
    if (error.name === 'NetworkError') {
      // There was a network failure in accessing the Store endpoint. 
      return;
    } else if (error.name === 'AccessError') {
      // There was an error in accessing UA provided offline values.
      return;
    }
  }
}

Accessing acquisition details

Once we've accessed the provider, we can asynchronously retrieve a dictionary payload of acquisition details through the getDetails() method which returns a ScriptPromise object.

details = await navigator.acquisitionInfoProvider.getDetails();
let installSource = details["installSource"]; // e.g. Microsoft Store
let campaignId = details["campaignId"]; // e.g. adCampaign202306

installSource is a required dictionary property with values dependent on the following scenarios:

  1. Microsoft Store | Google Play Store | Apple App Store - The web app was installed through one of these store platforms.

  2. Policy - The web app was installed due to an enterprise policy.

  3. Sync - The web app was installed as part of app sync.

  4. Preinstall - The web app was preinstalled on the device.

  5. <install origin> - For same-domain installation, the domain name of the web app. For cross-domain installation, the installer's domain name.

While installSource remains a required property, depending on the platform of the acquisition the pairs contained within the dictionary may differ to fit different store use cases.

Payload examples are taken from Play Install Referrer and Apple Ads Attribution documentation and are not final.

details = {
  installSource: "Google Play Store",
  installReferrer: "utm_source=google-play&utm_medium=organic",
  referrerClickTimestampSeconds: 1623214800,
  installBeginTimestampSeconds: 1623214810,
  installBeginReferrer: "utm_source=google-play&utm_medium=referral&utm_campaign=campaign-123",
  installVersion: "1.0.0",
  googlePlayInstant: false
}
details = {
  installSource: "Apple App Store",
  attribution: "true",
  orgId: "40669820",
  campaignId: "542370539",
  conversionType: "Download",
  adGroupId: "542317095",
  countryOrRegion: "US",
  keywordId: "87675432",
  adId: "542317136"
}

In the event that a web application has referral information that has expired for that specific application, or in any other case where acquisition info is missing for the web application, the API would return empty values for the associated properties in the dictionary. This is consistent with existing behavior in store information retrieval API for native applications.

details = {
  installSource: "Microsoft Store",
  campaignId: ""
}

Attribution on browser installs

While attribution is currently not being tracked in the same capacity as Store installations for browser-initiated installations of web applications, the Acquisition Info API could enable this sort of attribution capability.

Same-domain installation

Currently the main method of installing a PWA through the browser is navigating to the desired web application and initiating a same-domain installation. It may be the case that the intial navigation was due to an ad click. By having a standardized dictionary property (attributionId) that the UA is responsible for capturing to keep track of ad attribution, it becomes possible for the Acquistion Info API to return attribution information for browser-installed web applications as well. This attributionId dictionary property could be captured by the UA through a query string parameter such as __a_id in the GET parameters for the website. httpReferrer and installTimestamp are proposed as properties that should also be captured by the UA at install time and are included in every dictionary result for a browser-installed app.

Example same-domain use case

  1. User clicks on a Bing ads campaign on bar.com that navigates to foo.com?__a_id=bingAdsAug2023.

  2. User installs the foo.com PWA from foo.com.

  3. UA captures the attribution information to be eventually returned at the time of installation.

  4. Calling the Acquisition Info API getDetails() for foo.com PWA produces the following payload.

Proposed dictionary properties are not final and subject to change based on feedback.

details = {
  installSource: "foo.com",
  attributionId: "bingAdsAug2023",
  httpReferrer: "https://bar.com/",
  installTimestamp: "2023-08-16 10:30:00 UTC"
}

Web Install API (Cross-domain installation)

With the addition of the Web Install API, there exists a possibility of cross-domain browser-initiated installations that may have attribution information through the new capability of webapps to install other webapps. The Web Install API contains a referral-info parameter for its installation method, which contains an object that can hold arbitrary attribution information. The UA can capture the information contained in referral-info at install time so that the Acquisition Info API can return the data later.

Example cross-domain use case

For example, a user clicks on a Bing ads campaign on bar.com that navigates to the Microsoft Store website (apps.microsoft.com) product landing page for foo.com. foo.com may have defined that they want the Microsoft Store to also pass the region of installation and version of the app being installed as part of the acquisition information. This could be accomplished in the following fashion:

From apps.microsoft.com:

if ('install' in navigator) {
  // Build the referral-info object
  var referralInfo = {
    region: "US",
    installVersion: "1.0.0.0"
  };
  // Web install with additional attribution information
  const appInstalled = await navigator.install("foo.com", {"referral-info": referralInfo});
}

Result of a navigator.acquisitionInfoProvider.getDetails() call from the installed web app, foo.com:

details = {
  installSource: "apps.microsoft.com",
  attributionId: "bingAdsAug2023",
  httpReferrer: "https://bar.com/",
  installTimestamp: "2023-08-16 10:30:00 UTC",
  region: "US",
  installVersion: "1.0.0.0"
}

Other attribution cases

Policy applications

It's possible that a policy app could have associated attribution, perhaps implemented through its URL parameters. In this case queries to the API should reflect the type of app in its install source as well as that attribution information which will follow the same property convention as browser installations.

details = {
  installSource: "Policy",
  attributionId: "bingAdsAug2023"
}

Synced applications

When PWAs are synced across devices for the same user, the UA may make it easier to install that same set of PWAs. In this case, the acquisition information that is recorded for the originally acquired application should be maintained to be the same for all other installations. This applies to any and all other installation for the same user profile across any other device supported by the UA.

Considered Alternatives

Flattening the API

Right now, there is only one method available under the acquisitionInfoProvider attribute, so it seems a natural course of action to remove the inbetween layer of acquisitionInfoProvider and instead have a navigator.getAcquisitionInfoDetails() method.

// Detecting if the API is supported in this context.
if (getAcquisitionInfoDetails in navigator) {
  try {
    let details = await navigator.getAcquisitionInfoDetails();
    // Use the returned dictionary here.
    ...
  }
}

However, doing so eliminates the possibility of future additional functionality attached to the attribute. In this case, ensuring all of the acquisition info related methods remain under acquisitionInfoProvider provides clean categorization rather than cluttering navigator with multiple possible methods.

Attaching to the Get Installed Related Apps API

The possiblity of attaching acquisition as metadata to the navigator.getInstallRelatedApps() API as it already returns installed app data such as url and platform exists.

const relatedApps = await navigator.getInstalledRelatedApps();
relatedApps.forEach((app) => {
  console.log(app.installSource, app.campaignId);
});

However, considering the information that the method covers, it likely isn't the correct place to put acquisition related information. It's not a clear user experience mapping to call the Get Installed Related Apps API to get acquisition related information. Additionally, since in the proposed solution for the Acquisition Info API a myraid of acquistion related attributes is able to be returned, the Get Installed Related Apps API return fields would quickly become overcrowded with unrelated information.

Non-API web app start-up params

When an installed web application is launched, acquisition information such as campaign ID could be inserted into the launch URL parameters for the web app. However, this would mean any networked communications would have to take place during the start-up process of the web application, and acquisition information would only be retrievable on the landing page of the installed web application prior to any navigation within the page. The flexibility of the acquisition information would also become greatly limited without overcrowding the query parameters.

Privacy and Security Considerations

  1. Lack of validation: It is assumed that the install source does not perform any validation or sanitation of the acquisition data retrieved itself.

  2. User control regarding acquisition information: For browser installed web apps, it is recommended that the UA clears saved acquisition information if the user clears cached site data. For store installed web apps, we recognize that different vendors may have specific preferences and requirements regarding this aspect, so we defer to the individual install sources for handling of stored acquisition information.

  3. Potential misuse of acquisition identifiers: Acquisition identifiers could potentially be manipulated or obscured by ad networks or referral sources, similar to the existing practices in advertising. However, this behavior is not specific to the proposed API and is already possible with ad campaigns.

This API can only be invoked in a top-level secure context. This is in order to prevent attackers from accessing privacy information that is being exposed in this API.

Glossary

Term Definition
Attribution Identifying the source that led to an installation.
Acquisition Installation of the application in question.
PWA Progressive Web App
UWP Universal Windows Platform
API Application Programming Interface
WinRT Windows Runtime
Store Microsoft Store
App Application
Campaign ID A unique identifier that is associated with a specific ad campaign.
UA User Agent

Open Questions

How should we be filtering the information returned in getDetails()?

The flexibility outlined in the current return fields offers a potential vulnerability in not filtering the information being surfaced. This means that fields could even contain unintended information. If we were to mitigate this in scoping down the fields that are returned down to specific values or lengths, what would that look like? What values are we interested in across all platforms?