am 9aede602: am c8543b4f: Merge "docs: Fixes to the Data Layer Wear class."...

      <a href="{@docRoot}sdk/installing/studio-build.html">Building Your Project with

      Gradle</a> for more information about Gradle.</p></li>

  <li>Add a new build rule under <code>dependencies</code> for the latest version of

<code>play-services</code>. For example:

      <code>play-services</code>.

      <p>For example, for mobile modules:</p>

<pre class="no-pretty-print">

apply plugin: 'android'

...

    compile 'com.android.support:appcompat-v7:20.+'

    <strong>compile 'com.google.android.gms:play-services:6.1.+'</strong>

}

</pre>

      <p>For wearable modules:</p>

<pre class="no-pretty-print">

apply plugin: 'android'

...

dependencies {

    <strong>compile 'com.google.android.gms:play-services-wearable:6.1.+'</strong>

}

</pre>

      <p>Be sure you update this version number each time Google Play services is updated.</p>

  </li>

</div>

</div>

<p>To call the data layer API, create an instance of

<p>To call the Data Layer API, create an instance of

<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html"><code>GoogleApiClient</code></a>,

the main entry point for any of the Google Play services APIs.

</p>

                @Override

                public void onConnected(Bundle connectionHint) {

                    Log.d(TAG, "onConnected: " + connectionHint);

                    // Now you can use the data layer API

                    // Now you can use the Data Layer API

                }

                @Override

                public void onConnectionSuspended(int cause) {

href="{@docRoot}google/auth/api-client.html#WearableApi">Access the Wearable API</a>.</p>

<p>Before you use the data layer API, start a connection on your client by calling the

<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html#connect()">connect()</a>

<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html#connect()">

<code>connect()</code></a>

method, as described in

<a href="{@docRoot}google/auth/api-client.html#Starting">Accessing Google Play services APIs</a>.

When the system invokes the <code>onConnected()</code> callback for your client, you're ready

to use the data layer API.</p>

<a href="{@docRoot}google/auth/api-client.html#Starting">Start a Connection</a>.

When the system invokes the

<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.ConnectionCallbacks.html#onConnected(android.os.Bundle)">

<code>onConnected()</code></a> callback for your client, you're ready to use the Data Layer API.</p>

<p>

To send large blobs of binary data over the Bluetooth transport, such as images, attach an

<a href="{@docRoot}reference/com/google/android/gms/wearable/Asset.html">Asset</a> to a

<a href="{@docRoot}reference/com/google/android/gms/wearable/Asset.html"><code>Asset</code></a> to a

data item and the put the data item into the replicated data store.

</p>

<p>Assets automatically handle caching of data to prevent retransmission and conserve Bluetooth bandwidth.

A common pattern is for a handheld app to download an image, shrink it to an appropriate size

for display on the wearable, and transmit it to the wearable app as an Asset. The following examples

demonstrates this pattern.

for display on the wearable, and transmit it to the wearable app as an asset. The following examples

demonstrate this pattern.

</p>

<p class="note"><b>Note:</b> Although the size of data items are limited to 100KB,

assets can be as large as desired. However, transferring large assets affect the

<p class="note"><b>Note:</b> Although the size of data items is limited to 100KB,

assets can be as large as desired. However, transferring large assets affects the

user experience in many cases, so test your apps to ensure that they perform well

if you're transferring large assets.

<p>

</pre>

<p>When you have an asset, attach it to a data item with the <code>putAsset()</code> method in

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataMap.html"><code>DataMap</code></a>

or

<a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html"><code>PutDataRequest</code></a>

        .putDataItem(mGoogleApiClient, request);

</pre>

<h2 id="ReceiveAsset">Receive assets</h2>

<p>

When an asset is created, you probably want to read and extract

it on other side of the connection. Here's an example of how to implement the

callback to detect an asset change and extract the Asset:

callback to detect an asset change and extract the asset:

</p>

<pre>

</div>

<p>

A <a href="@{docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a>

A <a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a>

defines the data interface that the system uses to synchronize data between handhelds

and wearables. A <a href="@{docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a> generally

and wearables. A <a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a> generally

consists of the following items:</p>

<ul>

  <li><b>Payload</b> - A byte array, which you can set with whatever data you wish, allowing you

</ul>

<p>

You normally don't implement <a href="@{docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a>

You normally don't implement <a href="{@docRoot}reference/com/google/android/gms/wearable/DataItem.html"><code>DataItem</code></a>

directly. Instead, you:

<ol>

  <li>Create a <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html"><code>PutDataRequest</code></a> object,

  specifying a string path to uniquely identify the item.

  </li>

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html#setData(byte[])">setData()</a> to set

  the payload.

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/PutDataRequest.html#setData(byte[])">

  <code>setData()</code></a> to set the payload.

  </li>

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>DataApi.putDataItem()</code></a> to request the system to create the data item.

  </li>

a data item in an easy-to-use {@link android.os.Bundle}-like interface.

</p>

<h2 id="SyncData">Sync Data with a Data Map</h2>

<p>

When possible, use the <a href="{@docRoot}reference/com/google/android/gms/wearable/DataMap.html"><code>DataMap</code></a> class.

  <li>Call <a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>DataApi.putDataItem()</code></a> to request the system to create the data item.

  <p class="note"><b>Note:</b>

  If the handset and wearable devices are disconnected,

  the data is buffered and and synced when the connection is re-established.

  the data is buffered and synced when the connection is re-established.

  </p>

  </li>

</ol>

<p>The following example shows how to create a data map, set data on it, and create it:</p>

<p>The following example shows how to create a data map and put data on it:</p>

<pre>

PutDataMapRequest dataMap = PutDataMapRequest.create("/count");

You can do this by implementing a listener for data item events.

<p>For example, here's what a typical callback looks like to carry out certain actions

when data changes.</p>

when data changes:</p>

<pre>

@Override

<p>

This is just a snippet that requires more implementation details. Learn about

how to implement a full listener service or activity in

<a href="{@docRoot}training/wearables/data-layer/events.html#Listen">Listening for Data Layer Events</a>.

<a href="{@docRoot}training/wearables/data-layer/events.html#Listen">Listen for Data Layer

Events</a>.

</p>

 No newline at end of file

</div>

</div>

<p>When you make calls with the data layer, you can receive the status

<p>When you make calls to the Data Layer API, you can receive the status

of the call when it completes as well as listen for any changes that

the call ends up making with listeners.

</p>

<h2 id="Wait">Wait for the Status of Data Layer Calls</h2>

<p>You'll notice that calls to the data layer API sometimes return a

<p>You'll notice that calls to the Data Layer API sometimes return a

<a href="{@docRoot}reference/com/google/android/gms/common/api/PendingResult.html"><code>PendingResult</code></a>,

such as

<a href="{@docRoot}reference/com/google/android/gms/wearable/DataApi.html#putDataItem(com.google.android.gms.common.api.GoogleApiClient, com.google.android.gms.wearable.PutDataRequest)"><code>putDataItem()</code></a>.

lets you wait for the result status, either synchronously or asynchronously.

</p>

<h3 id="async-waiting">Asynchronously waiting</h3>

<p>If your code is running on the main UI thread, do not making blocking calls

to the data layer API. You can run the calls asynchronously by adding a callback

<h3 id="async-waiting">Asynchronous calls</h3>

<p>If your code is running on the main UI thread, do not make blocking calls

to the Data Layer API. You can run the calls asynchronously by adding a callback method

to the <a href="{@docRoot}reference/com/google/android/gms/common/api/PendingResult.html"><code>PendingResult</code></a> object,

which fires when the operation is completed:</p>

<pre>

});

</pre>

<h3 id="sync-waiting">Synchronously waiting</h3>

<h3 id="sync-waiting">Synchronous calls</h3>

<p>If your code is running on a separate handler thread in a background service (which is the case

in a <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html"><code>WearableListenerService</code></a>),

it's fine for the calls to block. In this case, you can call

<a href="{@docRoot}reference/com/google/android/gms/common/api/PendingResult.html#await()"><code>await()</code></a>

on the PendingResult object, which will block until the request has completed, and return a Result

on the <a href="{@docRoot}reference/com/google/android/gms/common/api/PendingResult.html"><code>PendingResult</code></a>

object, which blocks until the request completes and returns a

<a href="{@docRoot}reference/com/google/android/gms/common/api/Result.html"><code>Result</code></a>

object:

</p>

  </li>

</ul>

<p>With both these options, you override any of the data event callbacks that you care about

handling in your implementation.</p>

<p>With both these options, you override the data event callback methods for the events you

are interested in handling.</p>

<h3 id="listener-service">With a WearableListenerService</h3>

<p>

You typically create instances of this service in both your wearable and handheld apps. If you

don't care about data events in one of these apps, then you don't need to implement this

are not interested in data events in one of these apps, then you don't need to implement this

service in that particular app.</p>

<p>For example, you can have a handheld app that sets and gets data item objects and a wearable app

-  A message sent from one side of a connection triggers this callback on the other side of the connection.</li>

  <li><a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html#onMessageReceived(com.google.android.gms.wearable.MessageEvent)"><code>onPeerConnected()</code></a>

  and <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html#onPeerDisconnected(com.google.android.gms.wearable.Node)"><code>onPeerDisconnected()</code></a> -

  Called when connection with the handheld or wearable is connected or disconnected.

  Changes in connection state on one side of the connection triggers these callbacks on both sides of the connection.

  Called when the connection with the handheld or wearable is connected or disconnected.

  Changes in connection state on one side of the connection trigger these callbacks on both sides

  of the connection.

  </li>

</ul>

  <li>Create a class that extends

  <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html"><code>WearableListenerService</code></a>.

  </li>

  <li>Listen for the events that you care about, such as

  <a href="{@docRoot}/reference/com/google/android/gms/wearable/WearableListenerService.html#onDataChanged(com.google.android.gms.wearable.DataEventBuffer)"><code>onDataChanged()</code></a>.

  <li>Listen for the events that you're interested in, such as

  <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html#onDataChanged(com.google.android.gms.wearable.DataEventBuffer)"><code>onDataChanged()</code></a>.

  </li>

  <li>Declare an intent filter in your Android manifest to notify the system about your

  <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html"><code>WearableListenerService</code></a>.

            // Get the node id from the host value of the URI

            String nodeId = uri.getHost();

            // Set the data of the message to be the bytes of the URI.

            // Set the data of the message to be the bytes of the URI

            byte[] payload = uri.toString().getBytes();

            // Send the RPC

<h4>Permissions within Data Layer Callbacks</h4>

<p>In order to deliver callbacks to your application for data layer events, Google Play services

<p>

To deliver callbacks to your application for data layer events, Google Play services

binds to your <a href="{@docRoot}reference/com/google/android/gms/wearable/WearableListenerService.html"><code>WearableListenerService</code></a>,

and calls your callbacks via IPC. This has the consequence

that your callbacks inherit the permissions of the calling process.</p>

<li>Implement the desired interfaces.</li>

<li>In {@link android.app.Activity#onCreate}, create an instance of

<a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html"><code>GoogleApiClient</code></a>

to work with the data layer API.

to work with the Data Layer API.

<li>

In {@link android.app.Activity#onStart onStart()}, call <a href="{@docRoot}reference/com/google/android/gms/common/api/GoogleApiClient.html#connect()"><code>connect()</code></a> to connect the client to Google Play services.

</li>