Is There a Way To Put a PWA/TWA App in a Sub-Domain

Question

I am trying to add Progressive Web Apps to my server. I would prefer not to create a new web site for each app. My preference is to add each app to a sub-domain off of a website like this: www.example.com/app1

The problem is that when I run the Statement List Generator here: https://developers.google.com/digital-asset-links/tools/generator

It only works if I place assetlinks.json here: www.example.com. And if that is the case then I can only have one app in www.example.com. I have tried placing assetlinks.json here 1) www.example.com/app1 2) www.example.com/app1/.well-known and 3) www.example.com . The only one that works is #3.

Have also added the following intent filter to androidmanifest.xml and that does not work:

<intent-filter android:label="@string/app_name" android:autoVerify="true" >
            <action android:name="android.intent.action.VIEW"/>
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE"/>
            <!-- Edit android:host to handle links to the target URL-->
            <data android:scheme="https"
                android:host="example.com"
                android:pathPrefix="/app1" />
</intent-filter>

I can't believe that you must have a different website for each progressive web app. Any suggestions?

Answer 1

It is possible to do it. As an example, let's say you are developing 2 applications:

• https://example.com/app1
• https://example.com/app2

And, since those applications are going to be different TWAs, that also means you will have a different package-name for each one:

• com.example.app1, which launches https://example.com/app1
• com.example.app2, which launches https://example.com/app2

The assetlinks.json file should be available at https://example.com/.well-known/assetlinks.json and should list both applications:

[
  {
    "relation": ["delegate_permission/common.handle_all_urls"],
    "target" : { "namespace": "android_app", "package_name": "com.example.app1",
                 "sha256_cert_fingerprints": ["<APP_1_FINGERPRINT>"] }
  }, 
  {
    "relation": ["delegate_permission/common.handle_all_urls"],
    "target" : { "namespace": "android_app", "package_name": "com.example.app2",
                 "sha256_cert_fingerprints": ["<APP_2_FINGERPRINT>"] }
  }

]

Each application will have its own asset_statements declaration, linking the app to the authorised origin:

[{ "relation": ["delegate_permission/common.handle_all_urls"],
   "target": {"namespace": "web", "site": "https://example.com"}}]

A couple of things to be aware of:

1. If Application 1 will open https://example.com/app1. But, if the user navigates to https://example.com/app2, they will remain in full-screen. The same is true for Application 2 navigating to /app1.
2. It would be possible for Application 1 to start a TWA opening https://example.com/app2, and vice-versa. So, if you don't trust all the PWAs and the corresponding applications, this approach is not recommended.

If any of the two items above are an issue, using sub-domains would be a better solution.