am eef2f6f4: am 75a3f34e: am 3b521a6a: am 38097510: docs: M Preview -...

page.title=Automatic App Data Backup

page.title=Auto Backup for Apps

page.tags=backup

@jd:body

<div id="qv-wrapper">

  <div id="qv">

    <h2>In this document</h2>

      <ol>

        <li><a href="#overview">Overview</a></li>

        <li><a href="#configuring">Configuring Data Backup</a></li>

        <li><a href="#testing">Testing Backup Configuration</a></li>

        <li><a href="#issues">Known Issues</a></li>

      </ol>

  </div>

</div>

<p>

  Users often invest significant time and effort collecting data and setting preferences within

  Users often invest significant time and effort creating data and setting preferences within

  apps. Preserving that data for users if they replace a broken device or upgrade to a new one is

  an important part of ensuring a great user experience. The Android M Preview system helps ensure

  a good experience for users in this circumstances by automatically backing up app data to the

  cloud.

  an important part of ensuring a great user experience. Devices running the Android M Preview

  system help ensure a good experience for users in these circumstances by automatically backing up

  app data to Google Drive. The app data is automatically restored if a user changes or upgrades a

  device.

</p>

<p>

  This behavior is enabled by default for all apps installed on devices running Android M or

  higher. No additional app code is required. The system provides users with the ability opt out of

  automatic data backups for individual apps. You can also choose to limit what data from your app

  is backed up.

  Automatic backups are enabled for all apps installed on devices running the Android M Preview. No

  additional app code is required. The system provides users with the ability opt out of automatic

  data backups. You can also choose to limit what data from your app is backed up.

</p>

<p>

  your app.

</p>

<h2>Overview</h2>

<h2 id="overview">Overview</h2>

<p>

  The automatic backup feature preserves the data your app creates on a user device by uploading to

  the user’s Google Drive account and encrypting it. There is no charge to you or the user for data

  storage and the saved data does not count towards the user's personal Drive quota. During the M

  Preview period, users can store up to 25MB per Android app.

  The automatic backup feature preserves the data your app creates on a user device by uploading it

  to the user’s Google Drive account and encrypting it. There is no charge to you or the user for

  data storage and the saved data does not count towards the user's personal Drive quota. During

  the M Preview period, users can store up to 25MB per Android app.

</p>

<p>

  Automatic backups occur every 24 hours, when the device is idle, charging, and connected to a

  Wi-Fi network. When these conditions are met, the Backup Manager service uploads all available

  backup data to the cloud. When the user transitions to a new device, or uninstalls and reinstalls

  the backed up application, a restore operation will take place, copying the backed up data into

  the newly installed application’s data directory.

  the backed up app, a restore operation copies the backed up data into the newly installed

  app’s data directory.

</p>

<p class="note">

  <strong>Note:</strong> If your app uses the legacy

  <a href="{@docRoot}google/backup/index.html">Android Backup service</a>, this new behavior

  does not apply and the existing backup behavior works as usual.

</p>

<h3>Automatically Excluded Data Files</h3>

<h3 id="auto-exclude">Automatically Excluded Data Files</h3>

<p>

  Not all app data should be backed up, such as temporary files and caches, so the automatic backup

</p>

<ul>

  <li>Files in the directories referred to by the <code><a href=

  "{@docRoot}reference/android/content/Context.html#getCacheDir()">getCacheDir()</a></code> and

  <code><a href=

  "{@docRoot}reference/android/content/ContextWrapper.html#getCodeCacheDir()">getCodeCacheDir()</a></code>

  <li>Files in the directories referred to by the {@link android.content.Context#getCacheDir

    getCacheDir()} and {@link android.content.ContextWrapper#getCodeCacheDir getCodeCacheDir()}

    methods.

  </li>

  <li>Files located on external storage, unless they reside in the directory referred to by the

  <code><a href=

  "{@docRoot}reference/android/content/Context.html#getExternalFilesDir(java.lang.String)">getExternalFilesDir()</a></code>

    {@link android.content.Context#getExternalFilesDir getExternalFilesDir()}

  method.

  </li>

  <li>Files located in the directory referred to by the <code><a href=

  "{@docRoot}reference/android/content/Context.html#getNoBackupFilesDir()">getNoBackupFilesDir()</a></code>

  method.

  <li>Files located in the directory referred to by the

    {@link android.content.Context#getNoBackupFilesDir getNoBackupFilesDir()} method.

  </li>

</ul>

<h2>Configuring Data Backup</h2>

<h2 id="configuring">Configuring Data Backup</h2>

<p>

  The data created by any app installed on an M device is backed up, except for the automatically

  excluded files listed in the previous section. You can further limit and configure what data gets

  backed up from your app using settings in your app manifest.

  The data created by any app installed on an M Preview device is backed up, except for the

  automatically excluded files listed in the previous section. You can further limit and configure

  what data gets backed up from your app using settings in your app manifest.

</p>

<h3>Including or Excluding Data</h3>

<h3 id="include-exclude">Including or Excluding Data</h3>

<p>

  Depending on what data your application needs and how you save it, you may need to set specific

  Depending on what data your app needs and how you save it, you may need to set specific

  rules for including or excluding certain files or directories. The automatic backup service

  supports setting these backup rules through use of an XML configuration file and the app

  manifest. In the app manifest, you can specify a backup scheme configuration file as shown in the

        package="com.my.appexample">

    <uses-sdk android:minSdkVersion="9"/>

    <uses-sdk android:targetSdkVersion="android-MNC"/>

    <application ...

    <app ...

<strong>        android:fullBackupContent="&#64;xml/mybackupscheme"&gt;</strong>

    </application>

    </app>

    ...

</manifest>

</pre>

<p>

  In this example code, the android:fullBackupContent attribute specifies an XML file, located in

  the <code>res/xml/</code> directory of your app development project, named

  <code>mybackupscheme.xml</code>. This configuration file can include rules for what files are

  backed up. The following example code shows a configuration file that excludes a specific file

  from backups:

  In this example code, the <code>android:fullBackupContent</code> attribute specifies an XML file,

  located in the <code>res/xml/</code> directory of your app development project, named

  <code>mybackupscheme.xml</code>. This configuration file includes rules for what files are backed

  up. The following example code shows a configuration file that excludes a specific file from

  backups:

</p>

<pre>

</pre>

<p>

  This backup configuration only excludes a specific database file from being backed up. All other

  files are backed up.

  This example backup configuration only excludes a specific database file from being backed up.

  All other files are backed up.

</p>

<h4>Backup Configuration Syntax</h4>

  <li>

  <code>&lt;include&gt;</code>. Use this element if you want to specify a set of resources to

  back up, instead of having the system back up all data in your app by default. When you specify

	an <code>&lt;include&gt;</code> tag, the system backs up only the resources specified with this

	element.

  an <code>&lt;include&gt;</code> tag, the system backs up <em>only the resources specified</em>

  with this element.

  </li>

  <li>

    <li>

    <code>file</code>. Corresponds to a resource in the directory returned by the

		<code><a href="{@docRoot}reference/android/content/Context.html#getFilesDir()">getFilesDir()</a></code>

		method.

    {@link android.content.Context#getFilesDir getFilesDir()} method.

    </li>

    <li>

		<code>database</code>. Corresponds to a database returned by the <code><a href=

		"{@docRoot}reference/android/content/Context.html#getDatabasePath(java.lang.String)">getDatabasePath()</a></code>

		method or by using the <code><a href=

		"{@docRoot}reference/android/database/sqlite/SQLiteOpenHelper.html">SQLiteOpenHelper</a></code>

		class.

    <code>database</code>. Corresponds to a database returned by the

    {@link android.content.Context#getDatabasePath getDatabasePath()} method or by using the

    {@link android.database.sqlite.SQLiteOpenHelper} class.

    </li>

    <li>

		<code>sharedpref</code>. Corresponds to a <code><a href=

		"{@docRoot}reference/android/content/SharedPreferences.html">SharedPreferences</a></code>

		object returned by the <code><a href=

		"{@docRoot}reference/android/content/Context.html#getSharedPreferences(java.lang.String,%20int)">

		getSharedPreferences()</a></code> method.

    <code>sharedpref</code>. Corresponds to a {@link android.content.SharedPreferences} object

    returned by the {@link android.content.Context#getSharedPreferences getSharedPreferences()}

    method.

    </li>

    <li>

    <code>external</code>. Specifies that the resource is in external storage, and corresponds

		to a file in the directory returned by the <code><a href=

		"{@docRoot}reference/android/content/Context.html#getExternalFilesDir(java.lang.String)">getExternalFilesDir()</a></code>

		method.

    to a file in the directory returned by the

    {@link android.content.Context#getExternalFilesDir getExternalFilesDir()} method.

    </li>

    <li>

</ul>

<h3>Prohibiting Data Backups</h3>

<h3 id="prohibit">Prohibiting Data Backups</h3>

<p>

  You can choose to prevent automatic backups of any of your app data by setting the

  <code>android:allowBackup</code> attribute to <code>false</code> in the application element of

  <code>android:allowBackup</code> attribute to <code>false</code> in the app element of

  your manifest. This setting is illustrated in the following example code:

</p>

        package="com.my.appexample">

    <uses-sdk android:minSdkVersion="9"/>

    <uses-sdk android:targetSdkVersion="android-MNC"/>

    <application ...

    <app ...

<strong>        android:allowBackup="false"&gt;</strong>

    </application>

    </app>

    ...

</manifest>

</pre>

<h2>Testing Backup Configuration</h2>

<h2 id="testing">Testing Backup Configuration</h2>

<p>

  Once you have created a backup configuration, you should test it to make sure your app saves data

  performing a test backup:

</p>

<pre>$ adb shell setprop log.tag.BackupXmlParserLogging VERBOSE</pre>

<pre class="noprettyprint">

$ adb shell setprop log.tag.BackupXmlParserLogging VERBOSE

</pre>

<h4>Testing Backup</h4>

<p>To manually run a backup, first you must initialize the Backup Manager by calling the following

  command:

</p>

<pre class="noprettyprint">

$ adb shell bmgr run

</pre>

<p>

  To manually enable a backup, call the following command, specifying the package name for your app

  as the <code>&lt;PACKAGE&gt;</code> parameter:

  Next, you manually backup your application using the following command, specifying the package

  name for your app as the <code>&lt;PACKAGE&gt;</code> parameter:

</p>

<pre>$ adb shell bmgr fullbackup &lt;PACKAGE&gt;</pre>

<pre class="noprettyprint">

$ adb shell bmgr fullbackup &lt;PACKAGE&gt;</pre>

<h4>Testing Restore</h4>

<p>

  To manually initiate a restore after your app data is backed-up, call the following command,

  To manually initiate a restore after your app data is backed up, call the following command,

  specifying the package name for your app as the <code>&lt;PACKAGE&gt;</code> parameter:

</p>

<pre>$ adb shell bmgr restore &lt;PACKAGE&gt;</pre>

<pre class="noprettyprint">

$ adb shell bmgr restore <PACKAGE>

</pre>

<p class="warning">

  <b>Warning:</b> This action stops your app and wipes its data before performing the restore

<h4>Troubleshooting Backups</h4>

<p>

  If you run into issues, clear the backup data and associated metadata by calling this command.

  If you run into issues, you can clear the backup data and associated metadata by turning backup

  off and on in the <strong>Settings &gt; Backup</strong>, factory resetting the device, or by

  calling this command:

</p>

<pre>$ adb shell bmgr wipe &lt;TRANSPORT&gt; &lt;PACKAGE&gt;</pre>

<pre>$ adb shell bmgr list transports</pre>

<h2>Known Issues</h2>

<h2 id="issues">Known Issues</h2>

<p>The following are known issues with the automatic backup service:</p>

<ul>

  <li>For apps that use Google Cloud Messaging for push notifications, there is a known issue where

  backing up the registration id returned by Google Cloud Messaging registration can break push

  notifications for the restored application. It is important to query the API for a new

  registration id after being installed on a new device - which will not be the case if the old

  registration id was backed up. To avoid this, exclude the registration id from the set of backed

  <li><strong>Google Cloud Messaging</strong> -

  For apps that use Google Cloud Messaging for push notifications, there is a known issue where

  backing up the registration ID returned by Google Cloud Messaging registration can break push

  notifications for the restored app. It is important to query the API for a new

  registration ID after being installed on a new device, which is not be the case if the old

  registration ID was backed up. To avoid this, exclude the registration id from the set of backed

  up files.

  </li>

</ul>