{:external: target="_blank" .external} {:shortdesc: .shortdesc} {:codeblock: .codeblock} {:pre: .pre} {:screen: .screen} {:tsSymptoms: .tsSymptoms} {:tsCauses: .tsCauses} {:tsResolve: .tsResolve} {:tip: .tip} {:important: .important} {:note: .note} {:download: .download} {:java: .ph data-hd-programlang='java'} {:ruby: .ph data-hd-programlang='ruby'} {:c#: .ph data-hd-programlang='c#'} {:objectc: .ph data-hd-programlang='Objective C'} {:python: .ph data-hd-programlang='python'} {:javascript: .ph data-hd-programlang='javascript'} {:php: .ph data-hd-programlang='PHP'} {:swift: .ph data-hd-programlang='swift'} {:reactnative: .ph data-hd-programlang='React Native'} {:csharp: .ph data-hd-programlang='csharp'} {:ios: .ph data-hd-programlang='iOS'} {:android: .ph data-hd-programlang='Android'} {:cordova: .ph data-hd-programlang='Cordova'} {:xml: .ph data-hd-programlang='xml'}

{: #user_based_notifications}

User ID-based {{site.data.keyword.mobilepushshort}} are targeted at mobile app users with customized messages. With user-based notifications, you can choose to notify specific individuals based on their preferences.

{: #register_device_wh_userid}

To enable {{site.data.keyword.mobilepushshort}} targeted by User ID, ensure that you register the device with a User ID field set.

The User ID can be any string that the application provides to the device registration API. Typically, a mobile application will first run an authentication cycle where the mobile app user is authenticated against an authentication service such as {{site.data.keyword.amafull}}. On successful authentication, the authenticated user ID is then passed into the Push Device Registration API.

To register for userId-based notification, go through:

• Registering an Android application
• Registering an iOS application
• Registering a Cordova application
• Registering a web application

{: #using_userid}

The userId-based notifications are notification messages that are targeted to a specific user. Many devices can be registered with one user. The following steps describe how to send user ID-based notifications.

1. From the {{site.data.keyword.mobilepushshort}} console, click Notifications on the left navigation menu.
2. Click Create, and compose a message.
   • Compose a new notification by providing the following information: Notification text, Notification title (optional), Additional payload (optional).
   • Select the Target audience by one of the following targets:
     • Platforms - Options are: Android, iOS, Web Notifications, Chrome Apps and Extensions, Chrome Browser, Firefox, Safari, and All Devices.
     • Tags - Enter the Tag, topic name or create a new tag.
     • Devices/user IDs - Select the User ID and enter the user ID detail for the selection.
3. Click Send.

{: #sync_login_logout}

You can choose to send notifications only if the user is logged in.

For example, consider a device that is shared by members of a team at work, and there is a need to address specific users. In such a use case, there would be a user log-in and log out sequence. This authentication mechanism allows the application to track the identity of the present user of the application. This ensures that notifications that are targeted to a specific user are always received by that user only. After a successful log-in, start the device registration API passing the User ID of the logged-in user. Likewise, before logging out, start the device unregistration API. Sequencing these Push APIs with log-in and log out will ensure that notifications that are intended for a specific user is sent to that user only.