Sending service messages

# Sending service messages

Service messages is a feature of LINE MINI App that enables you to notify the user with information that the user should know as a response to or in confirmation of a particular user action on LINE MINI App. For example, if a user makes a reservation for a restaurant or accommodation on the LINE MINI App, you can send users for a single reservation action up to 5 service messages such as reservation completion or reminder the day before.

Conditions to sending service messages

You are allowed to send service messages only as a confirmation or response to a user action on LINE MINI App. Advertisements and event notifications are prohibited, including information on discounts, shopping rewards, new products, discount coupons or promotions. For more information about the service message conditions, see Conditions for service messages.

Service messages sent from LINE MINI Apps are displayed in chat rooms determined for each region that provides the LINE MINI App, regardless of the type of LINE MINI App.

Japan	Thailand	Taiwan
LINEミニアプリお知らせ	LINE MINI App Notice	LINE MINI App 通知

# Flow of sending a service message

To send a service message, you need a service message template and a service notification token. Follow these steps to send:

In the LINE Developers Console, add a service message template to the LINE MINI App channel.
Issue a service notification token and send a service message based on the user action on LINE MINI App.
Use the new service notification token issued in step 2 to send a subsequent service message, such as a reminder.

You need to pass review

Service message templates added to the LINE MINI App channel in step 1 need to pass review by LINE in order to be used with the Sending service messages API.

# Adding service message templates

From the templates provided by LINE, select a template to use with the Service Message API and add it to the LINE MINI App channel. You can configure up to 20 service message templates per LINE MINI App channel.

Templates are provided by category and you can find them in the LINE Developers Console. You can also send a test message to your LINE account to check a preview of the service message. To add a service message template, follow the steps:

From the LINE Developers Console, select the LINE MINI App channel to which you want to add a template and click the Service message template tab.

Note

You can proceed with preparing the official template while developing your channel.

During this time, you can:
- Add a new template
- See the list of all templates
- View template detail
- Edit the use case of a template
- Delete a template
- Send a test message available in the simulator

When review is in progress, some limitations apply to the use of the official template.

During this time, you can still:
- See the list of all templates
- Send a test message available in simulator
- View template detail
However, at this stage, you CANNOT:
- Add a new template
- Edit the use case of a template
- Delete a template

Once the channel is published, you can use the official template on the published channel (same condition apply as the preparation stage in #1).

While your channel is under review, you cannot add a new template. You can only send test messages available in the simulator until your channel passes review. The review process, however, does not affect existing templates (both official and custom templates) that have successfully been added in the past.

Click [Add].

Configure these settings:

Item	Description
Select template	Select a template to use with the Service Message API.
Template detail	The details of the selected template will be displayed. When executing the API for sending service messages, specify the string (`{template name}_{BCP 47 language tag}`) displayed in [Template name for API use] as `templateName`.
Preview	A preview of the test message will be displayed. When you click [Send] from [Send test message], the test message will be sent to the LINE account logged into the LINE Developers Console.
Send test message	Enter the JSON object that specifies the template variable-value pair. [Preview] will be updated with your entry. [Copy]: Copy the JSON object to clipboard. [Reset]: Discard edits to JSON object. [Send]: Send the test message to the LINE account logged into the LINE Developers Console.
Use Case	Enter the exact use case for the template.

Note

If you use templates in a manner that deviates from the explanation you entered in [Use Case], we may prevent you from using the templates.

Click [Add].

Return to the list of service message templates.

The status of the review will be displayed in [Published status] of the added template.

Published status	Description
DEVELOPING	Developing (Review not yet requested). This function is only available for sending service messages to developers with Admin or Tester privileges on the LINE MINI App channel, from a channel ready for publication.
PUBLISHING	Passed review. Used to send service messages from the production channel to the user of the LINE MINI App channel.

# Template elements

A service message consists of (A) title, (B) detail, (C) button, and (D) footer. Create a template by combining these sections according to the use case. Choose a template that best serves the purpose of your service message.

Label	Section	Description
A	Title	The title section consists of these elements. Title (A-1) Subtitle (A-2)
B	Detail	The detail section has two different layouts depending on template type: "detailed": One key required. the maximum number of keys depends on the template you select. For more information about counting characters, see Maximum number of characters for each element. "simple": You can select up to one key. For more information about counting characters, see Maximum number of characters for each element.
C	Button	The number of buttons you can use differs per template. Also, only buttons with configured URLs are displayed. Specify the Permanent link of your LINE MINI App page as the URL. The first button is required and is displayed as the first link in the message. The second button (and beyond) is optional and predefined based on the template you choose.
D	Footer	The icon set in the Channel icon and the channel name set in the Channel Name in the Basic settings tab are displayed. When the user taps the footer, your LINE MINI App top page will be displayed.

The footer when your LINE MINI App status isn't "Published"

If the status of your LINE MINI App is "Developing" or "Reviewing", the LINE icon along with the text, "Service Message", will be displayed in the footer section. Once the status changes to "Published", the LINE MINI App icon and LINE MINI App name that you configured will be displayed.

# Maximum number of characters for each element

In the Detail section, "detailed" and "simple" have the recommended and maximum number of characters (soft limit and hard limit) for each key value.

Item	Recommended number of characters	Soft limit	Hard limit
detailed	10	36	50
simple	32	100	150

We recommend that the value of each key be limited to the recommended number of characters. If the recommended number of characters is exceeded, characters overflowing the displayable area will be replaced by an ellipsis (...) or the service message can't be sent.

Number of characters	How the text is displayed
Recommended number of characters or less	All text will be displayed
Larger than the recommended number of characters, and the soft limit or less	Characters overflowing the displayable area may be replaced by an ellipsis (`...`)
Larger than the soft limit, and the hard limit or less	Characters overflowing the displayable area are replaced by an ellipsis (`...`)
Larger than the hard limit	Can't send service message due to error

The number of characters in the key values is counted in grapheme cluster (opens new window) units rather than UTF-16 code units. For more information about counting text characters, see Counting characters in a text in the Messaging API documentation.

# Sending service messages for the first time

Here are the steps to sending a service message for the first time from the LINE MINI App after a user action:

Test sending recommended

Before sending the service messages to users, we recommend that you test sending service messages and see how the message is displayed.

Use a short-lived channel access token to develop a LINE MINI App

Long-lived channel access tokens and channel access token with a user-specified expiration (Channel Access Token v2.1) cannot be used for LINE MINI App channels.

Use a short-lived channel access token to develop a LINE MINI App.

These are image diagrams showing how to issue a service notification token, using a channel access token and an access token obtained by liff.getAccessToken() (hereafter called "LIFF access token"), to send a service message. In these images, a short-lived channel access token is used as the channel access token.

relationship of tokens

AOA flow 1

Obtain the channel access token in advance.

The channel access token doesn't need to be reacquired each time you send a service message.
When notifying, obtain the LIFF access token by running the liff.getAccessToken() on your LINE MINI App.
Send the LIFF access token obtained in step 2 to your server.

Issue a service notification token.

Use the channel access token from step 1 and the LIFF access token from step 2. When the user closes the LINE MINI App, the LIFF access token will be revoked even if it hasn't expired.

final OkHttpClient notifierApiClient = new OkHttpClient().newBuilder().build();
final MediaType mediaType = MediaType.parse("application/json");
final RequestBody notificationTokenRequestBody = RequestBody.create(mediaType, "{'liffAccessToken': 'eyJhbGciOiJIUzI1NiJ9…'");
final Request notificationTokenRequest = new Request.Builder()
  .url(BASE_URL + "/notifier/token")
  .method("POST", notificationTokenRequestBody)
  .addHeader("Content-Type", "application/json")
  .addHeader("Authorization", "Bearer W1TeHCgfH2Liwa...")
  .build();
final NotificationTokenResponse response = notifierApiClient.newCall(request).execute();
String notificationToken = notificationTokenResponse.getNotificationToken();
int tokenRemainingCount = notificationTokenResponse.getRemainingCount();

Sending a service message for the first time.

Use the service notification token obtained in step 4.

If the template you use has template variables, specify the key-value pair in the params. If you do not specify the template variable for the required element, an error will be returned.

Example of params:

{
  ...
  "params": {
    // params sample to be updated
    "variable-name": "value",
    "button_uri_1": "detailView?userId=1234&purchaseID=5678"
  }
  ...
}

final RequestBody notificationRequestBody = RequestBody.create(mediaType,"{
  'templateName': 'reservation_confirmation_en',
  'notificationToken': '34c11a03-b726-49e3-8ce0-949387a9…',
  'params': {
    'template-field-name': 'field-value',
    'template-field-name': 'field-value',
  }}");
final Request notificationRequest = new Request.Builder()
  .url(BASE_URL + "/notifier/send?target=service")
  .method("POST", notificationRequestBody)
  .addHeader("Content-Type", "application/json")
  .addHeader("Authorization", "Bearer W1TeHCgfH2Liwa...")
  .build();
final NotificationResponse notificationResponse = notifierApiClient.newCall(request).execute();
notificationToken = notificationResponse.getNotificationToken();
tokenRemainingCount = notificationResponse.getRemainingCount();

After sending the service message, keep the service notification token included in the response

After sending a service message, keep the service notification token (notificationToken) included in the response. This service notification token will be used to send subsequent service messages for the same user action. You can send service messages for the same user action as many times as the number of remainingCount included in the response as long as the token hasn't expired.

Each user action can be identified by the session ID (sessionId) included in the response.

A service notification token expires 1 year (31,536,000 seconds) after being issued. While it is still valid, for example, up to 5 service messages can be sent from the LINE MINI App for a single reservation action by the user. For more information on sending subsequent service messages, see Sending subsequent service messages.

AOA flow 2

AOA flow 3

# Sending subsequent service messages

When you send subsequent service messages for the same user action, use the service notification token that was included in the response when you last sent the service message.

For sending a subsequent service message, don't issue a service notification token by reusing the channel access token and the LIFF access token used to send the first service message.

...
JsonObject subsequentMessage = Json.createObjectBuilder()
  .add("notificationToken", notificationToken)
  .add("templateName", templateName)
  .add("params", templateData)
  .build();
...

if (tokenRemainingCount < 0)
{
  notificationRequestBody = RequestBody.create(mediaType, subsequentMessage.toString());
  notificationRequest = new Request.Builder()
        .url(BASE_URL + "/notifier/send?target=service")
        .method("POST", notificationRequestBody)
        .addHeader("Content-Type", mediaType.toString())
        .addHeader("Authorization", "Bearer W1TeHCgfH2Liwa...")
        .build();
  notificationResponse =
        notifierApiClient.newCall(notificationRequest).execute();
  notificationToken = notificationResponse.getNotificationToken();
  tokenRemainingCount = notificationResponse.getRemainingCount();
}

After sending the service message, keep the service notification token included in the response

Each user action can be identified by the session ID (sessionId) included in the response.

Flow of sending a service message Adding service message templates Template elements Maximum number of characters for each element Sending service messages for the first time Sending subsequent service messages