Understanding Digital Asset Links File: A Key to Efficient and Secure Deep Linking
Tags: mobile, android, programming
Published: 2024-02-21 14:56:13

### What is a Digital Asset Links File?

The Digital Asset Links file is an essential tool in the app development world for both Android and iOS, particularly when it comes to implementing deep linking effectively and securely. This JSON file establishes a trust relationship between your website and your app, ensuring that links opened on mobile devices directly lead to the corresponding app, if installed.

### How Does It Work?

The operation of Digital Asset Links involves a few key steps:

-   Hosting the File: The file must be hosted on the domain of the site, typically at the path `/.well-known/assetlinks.json`. This allows the mobile device's operating systems to verify whether a particular app is authorized to open links from a specific domain.
-   Automatic Verification: When a link is clicked, the device's operating system checks if there is an installed app with the domain verified in the Digital Asset Links file. If confirmed, the link opens directly in the app; otherwise, it will open in the default browser.

### File Structure

A typical example of the Digital Asset Links file is:

```json
[
  {
    "relation": ["delegate_permission/common.handle_all_urls"],
    "target": {
      "namespace": "android_app",
      "package_name": "com.example.yourapp",
      "sha256_cert_fingerprints": ["YOUR_SHA_256_CERT_FINGERPRINT"]
    }
  }
]
```

Each field serves a specific purpose:

-   relation: Defines the type of relationship between the site and the app. It's usually `["delegate_permission/common.handle_all_urls"]` for deep linking.
-   target: Specifies the target app with details like `package_name` and `sha256_cert_fingerprints` for Android.

### Android and iOS Versions

For Android, support for App Links was introduced in Android 6.0 (Marshmallow), and it has since become a standard for deep linking implementation.

On iOS, the equivalent concept is known as Universal Links and was introduced in iOS 9. Instead of using a Digital Asset Links file, iOS uses a file called `apple-app-site-association`.

### Solving Deep Linking Problems

The use of the Digital Asset Links file on Android and the `apple-app-site-association` file on iOS solves several common deep linking issues:

1.  Improved User Experience: Instead of asking the user whether they want to open a link in the app or browser, the link directly opens in the app if it is installed.
2.  Enhanced Security: These files ensure that only authorized apps can open links from a specific domain, preventing potential abuses.
3.  Ease of Implementation: Once set up, the management of deep links becomes much more streamlined and integrated, without the need for additional prompts or choices for the user.

### Conclusion

The Digital Asset Links file in Android and its iOS equivalent are fundamental for effective and secure deep linking implementation in modern apps. By ensuring that links correctly direct to the right apps, they not only enhance user experience but also increase the security and reliability of interactions between websites and mobile applications.