Joyn or RCS

RCS (Rich Communication Services) is a GSMA standard that aims to bring a set of rich communication (that goes beyond SMS and phone calls) yet inter-operable services  across different domains managed by different telecom operators. This telcos standard is marketed under the name of Joyn.
Many operators has already deployed on their networks offering users VoIP and presence services that can be accessed by installing an application from the market store (Google Play, AppStore). In addition, some smarphone manufacturers who have joined the movement already embed the RCS stack into their devices.

The next step of commercializing Joyn is to build an ecosystem by providing APIs and empowering the developers community to create communication-based applications that relies on the platform. Orange through Orange Partner and Deutsch Telekom through the Developer Garden programs are leading these efforts in Europe. For instance, they jointly sponsored the Joyn Hackathon (press release) were the Joyn API  was introduced.

The remaining of this post explains how to use the Android Joyn SDK to build conversational applications. The overall interaction between an application and the Joyn SDK (and behind the RCS platform) is explained in the following figure.

Joyn API call flow

1. Instantiate Joyn service and establish a connection

   private ChatService mService;
   private JoynServiceListener mListener = new JoynServiceListener() {
      @Override public void onServiceDisconnected(int error) {
         Log.i(TAG, "ChatService disconnected!");
      }
      @Override public void onServiceConnected() {
         Log.i(TAG, "ChatService connected!");
      }
   };
   ...
   // Instanciate API
   mService = new ChatService(getApplicationContext(), mListener); 
   // Connect API
   mService.connect();

2. When the the connection is successfully established then start calling API methods

   private Chat mChat;
   private ChatListener mChatListener = new ChatListener() {
      @Override public void onReportMessageFailed(String arg0) {}
      @Override public void onReportMessageDisplayed(String arg0) {}
      @Override public void onReportMessageDelivered(String arg0) {}
      @Override public void onNewMessage(ChatMessage arg0) {}
      @Override public void onComposingEvent(boolean arg0) {}
   };
   ...
   @Override public void onServiceConnected() {
      Log.i(TAG, "ChatService connected!");
      if (mService != null && mService.isServiceRegistered()) {
         // Get remote contact
         String contact = getIntent().getStringExtra("contact");
         // Call API Methods
         mChat = mService.openSingleChat(contact, mChatListener); 
         mChat.sendMessage("hello world!");
      }
   }

The API doc of the ChatService can be found on this link.

Using Speech Input API

The Android SDK provides support for an easy integration of speech input into native applications. We need just to send out an intent RecognizerIntent (no permission is required) to call any available voice recognition service in the phone (e.g. Google Voice, Nuance Dragon API for mobile). Then, a list of recognized word is send back to the application which can capture them in the onActivityResult method.

Read more.

Text to Speech in Android

To use the Android Speech to Text API you need to implement the TextToSpeech.OnInitListener interface. In the onInit() method, check the returned status to value, it ca be TextToSpeech.SUCCESS for initialization success or TextToSpeech.ERROR in case of failure. If the initialization succeeded then set your preferred language to US english (or FRANCE for french). 
Note that a language may not be available, check the documentation for more information.
Here is a complete example of how to use the Speech to Text API.

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.speech.tts.TextToSpeech;
import android.util.Log;
import java.util.Locale;

public class MainActivity extends Activity implements TextToSpeech.OnInitListener {
 
 private String TAG = MainActivity.class.getSimpleName();
 private TextToSpeech mTts;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);        
        setContentView(R.layout.main);
        
        mTts = new TextToSpeech(this, this);
    } 

 @Override
 public void onInit(int status) {
        if (status == TextToSpeech.SUCCESS) {            
            int result = mTts.setLanguage(Locale.US);            
            if (result == TextToSpeech.LANG_MISSING_DATA || result == TextToSpeech.LANG_NOT_SUPPORTED) {
                Log.e(TAG, "Language data is missing or the language is not supported.");
            } else {                
               String text = "hello, do you hear me?";  
               mTts.speak(text,TextToSpeech.QUEUE_FLUSH, null);
}
        } else {
            Log.e(TAG, "Could not initialize TextToSpeech.");
        }
 }
}