1page.title=Data Saver mode 2@jd:body 3 4<!-- 5 Copyright 2016 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18--> 19<div id="qv-wrapper"> 20 <div id="qv"> 21 <h2>In this document</h2> 22 <ol id="auto-toc"> 23 </ol> 24 </div> 25</div> 26 27<p> 28Mobile data use is costly and even more so where data plan costs are not 29affordable by all. Android users need the ability to reduce data use or block it 30from apps altogether. The Data Saver feature in the Android 7.0 release provides 31this functionality to the user. 32</p> 33 34<p> 35The <a href="https://developer.android.com/preview/features/data-saver.html">Data Saver</a> 36feature can be turned on or off by the user. App developers 37should use a new API to check if Data Saver mode is on. If it is on, the app 38developers can handle the situation gracefully by tuning their applications for 39low- or no-data access. 40</p> 41 42<p> 43End users benefit as they will be able to control which apps can access data in 44the background and which can access data only while in the foreground. This 45ensures desired background data exchange when Data Saver is on per user control. 46</p> 47 48<h2 id="implementation">Implementation</h2> 49 50<p> 51Since the Data Saver is a feature in the platform, device manufacturers gain its 52functionality by default with the N release. 53</p> 54 55<h3 id="settings-interface">Settings interface</h3> 56 57<p> 58A default Data Saver settings user interface is supplied in the Android Open 59Source Project (AOSP). See the screenshots below for examples. 60</p> 61 62<p> 63These screenshots show the Data Saver mode in use. 64</p> 65 66<img src="images/data-saver-use.png" width="397" alt="Toggling Data Saver off/on" /> 67<p class="img-caption"> 68 <strong>Figure 1.</strong> Toggling Data Saver off/on 69 </p> 70 71<img src="images/data-battery-saver.png" width="641" alt="Battery saver and Data Saver are on" /> 72<p class="img-caption"> 73 <strong>Figure 2.</strong> When both battery saver and Data Saver are on 74 </p> 75 76<img src="images/data-saver-app.png" width="376" alt="App-specific data usage screen" /> 77<p class="img-caption"> 78 <strong>Figure 3.</strong> App-specific data usage screen: Settings > Apps > Data usage 79 </p> 80 81<img src="images/data-saver-quick-settings.png" width="446" alt="Data saver in the Quick Settings" /> 82<p class="img-caption"> 83 <strong>Figure 4.</strong> Data saver states on the Quick Settings menu 84 </p> 85 86<h3 id="apps">Apps</h3> 87 88<strong>Important</strong>: Partners should not whitelist apps. 89Even if they do, users may remove them. Including other 90apps forces users to decide on which to apply Data Saver. 91</p> 92 93<p> 94All app developers must act to implement Data Saver, including OEMs and carrier 95partners with preloaded apps. See <a 96href="https://developer.android.com/preview/features/data-saver.html">Data Saver 97on developer.android.com</a> for app developer instructions on detecting and 98monitoring Data Saver states. See the sections below for additional details 99helpful to partners. 100</p> 101 102<p> 103To optimize for Data Saver mode, apps should: 104</p> 105 106<ul> 107 <li>Remove unnecessary images 108 <li>Use lower resolution for remaining images 109 <li>Use lower bitrate video 110 <li>Trigger existing “lite” experiences 111 <li>Compress data 112 <li>Respect metered vs. unmetered network status even when Data Saver is 113off 114</ul> 115 116<p> 117Conversely, to work well with Data Saver, apps should not: 118</p> 119 120<ul> 121 <li>Autoplay videos 122 <li>Prefetch content/attachments 123 <li>Download updates / code 124 <li>Ask to be whitelisted unless background data is truly part of core 125 functionality 126 <li>Treat whitelisting as a license to use more bandwidth 127</ul> 128 129<h2 id="validation">Validation</h2> 130 131<p> 132Implementers can ensure their version of the feature works as intended by 133running the following CTS test: 134</p> 135 136<pre> 137com.android.cts.net.HostsideRestrictBackgroundNetworkTests 138</pre> 139 140<p> 141In addition, <code>adb</code> commands can be used to conduct tests manually by 142first running this command to see all available options:<br> 143<code>$ adb shell cmd netpolicy</code> 144</p> 145 146<p> 147For example, this command returns the UIDs of the whitelisted apps:<br> 148<code>$ adb shell cmd netpolicy list restrict-background-whitelist</code> 149</p> 150
