# Opening a LIFF app
The LIFF app can be opened in LINE's in-app browser or an external browser. This section describes the operations that allow users to open the LIFF app.
Users access the LIFF URL.
The LIFF URL is issued when Adding the LIFF app to your channel.
For example, enter the URL on the LINE chat screen and tap the URL displayed in the bubble to open the LIFF app.
Users agree to grant the required permissions to the LIFF app.
The LIFF app is displayed.
When users access the LIFF URL, the LIFF app will open in LINE's in-app browser or an external browser. Which environment is used depends on the Universal Links or App Links specifications.
# Behaviors from accessing the LIFF URL to opening the LIFF app
As announced on June 29, 2020, the LIFF app can now use the path (/path) and query parameter (?key=value) entered in the Endpoint URL of the LINE Developers console.
To use the new specs, set Methods for converting additional information in the LIFF URL to Concatenate.
We recommend using the new specs in the future.
Note the following:
- If your existing LIFF app doesn't support the new specs, set to Replace (Backward compatibility mode). In this case, the LIFF app isn't affected by the new specs.
- When adding a new LIFF app, it's set to Concatenate. The setting items aren't displayed. Edit them as needed.
The following describes how to set up two redirect destinations so that the LIFF app opens correctly when users access the LIFF URL, and when to execute the liff.init() method when users access the LIFF URL.
| Redirect to | Description |
|---|---|
| Primary redirect URL | The first time users access the LIFF URL, they are redirected from the LIFF server to this URL. When users are redirected to this URL, execute the liff.init() method. |
| Secondary redirect URL | When executing the liff.init() method, users are redirected to this URL. Once users are redirected to this URL, the LIFF app page is displayed. |
If executing the liff.init() method at the timing other than accessing the primary redirect URL, INIT_FAILED is returned and the LIFF app can't be opened.
# Create a LIFF URL
The LIFF URL is a URL that indicates the LIFF server provided by LINE. A LIFF URL is issued by adding the LIFF app to your channel.
# Create a primary redirect URL
The primary redirect URL is always the URL specified in the Endpoint URL of the LINE Developers console.
For the primary redirected URLs, regardless of the Methods for converting additional information in the LIFF URL setting, the additional information specified in the LIFF URL (for example: path_A/?key1=value1#URL-fragment) are all included in the liff.state query parameter.
For example: https://example.com/2020campaign/?key=value&liff.state=urlencoded(path_A/?key1=value1#URL-fragment)
If you don't specify any additional information in the LIFF URL, the liff.state query parameter is omitted.
# Create a secondary redirect URL
The secondary redirect URL depends on the setting of the Methods for converting additional information in the LIFF URL in LINE Developers console and the URL that users access.
# When setting [Methods for converting additional information in the LIFF URL] to [Concatenate]
The paths and query parameters (/2020campaign/?key=value) specified in the Endpoint URL of the LINE Developers console are included in the secondary redirect URL.
| URL that users access | Secondary redirect URL |
|---|---|
| LIFF URL (1) For example: https://liff.line.me/{liffId} | The URL specified in Endpoint URL of the LINE Developers console. For example: https://example.com/2020campaign/?key=value |
| The LIFF URL including additional information (2) For example: https://liff.line.me/{liffId}/path_A/?key1=value1#URL-fragment | As shown in (2) of the below figure, the URL is a combination of 3 types of information.
https://example.com/2020campaign/path_A/?key=value&key1=value1#URL-fragment |
# When setting [Methods for converting additional information in the LIFF URL] to [Replace (Backward compatibility mode)]
The paths and query parameters (for example: /2020campaign/?key=value) specified in the Endpoint URL of the LINE Developers console may not be included in the secondary redirect URL.
| URL that users access | Secondary redirect URL |
|---|---|
| LIFF URL | The URL specified in Endpoint URL of the LINE Developers console. For example: https://example.com/2020campaign/?key=valueNote: Depending on the setting of Endpoint URL, the specified paths and query parameters ( /2020campaign/?key=value) may not be included in the secondary redirect URL. |
| The LIFF URL including additional information | The URL combines these 2 types of information.
https://example.com/path_A/?key1=value1#URL-fragmentNote: The paths and query parameters ( /2020campaign/?key=value) specified in Endpoint URL aren't included in the secondary redirect URL. |
If the current page URL doesn't begin with the URL specified in Endpoint URL when executing the liff.permanentLink.createUrl() method, you aren't able to get a permanent link.
Especially when setting Methods for converting additional information in the LIFF URL to Replace (Backward compatibility mode), the paths and query parameters (/2020campaign/?key=value) specified in Endpoint URL may not be included in the secondary redirect URL.
In this case, you can't get a permanent link because the liff.permanentLink.createUrl() method meets the above conditions.