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Signaling Quickstart

Updated

Rapidly develop your first Signaling app.

Use Signaling SDK to add low-latency, high-concurrency signaling and synchronization capabilities to your app.

Signaling also helps you enhance the user experience in Video Calling, Voice Calling, Interactive Live Streaming, and Broadcast Streaming applications.

This page shows you how to use the Signaling SDK to rapidly build a simple application that sends and receives messages. It shows you how to integrate the Signaling SDK in your project and implement pub/sub messaging through Message channels. To get started with stream channels, follow this guide to create a basic Signaling app and then refer to the Stream channels guide.

Understand the tech

To use Signaling features in your app, you initialize a Signaling client instance and add event listeners. To connect to Signaling, you login using an authentication token. To send a message to a message channel, you publish the message. Signaling creates a channel when a user subscribes to it. To receive messages other users publish to a channel, your app listens for events.

To create a pub/sub session for Signaling, implement the following steps in your app:

Prerequisites

To implement the code presented on this page you need to have:

  • An Agora account and project.

  • Enabled Signaling in Agora Console

  • Android Studio 4.1 or higher.

  • Android SDK API Level 24 or higher.

  • A mobile device that runs Android 4.1 or higher.

  • Ensure that a firewall is not blocking your network communication.

Signaling 2.x is an enhanced version compared to 1.x with a wide range of new features. It follows a new pricing structure. See Pricing for details.

Project setup

Create a project

  1. Create a new project.

    1. Open Android Studio and select File > New > New Project....

    2. Select Phone and Tablet > Empty Activity and click Next.

    3. Set the project name and storage path.

    4. Select Java or Kotlin as the language, and click Finish to create the project.

      After you create a project, Android Studio automatically starts gradle sync. Ensure that the synchronization is successful before proceeding to the next step.

  2. Add network permissions

    Open the /app/src/main/AndroidManifest.xml file and add the following permissions before <application>:

    <uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

  3. Prevent code obfuscation

    Open the /app/proguard-rules.pro file and add the following line to prevent code obfuscation:

    -keep class io.agora.**{*;}

Integrate the SDK

Use either of the following methods to integrate Signaling SDK into your project.

Using Maven Central

  1. Open the settings.gradle file in the project's root directory and add the Maven Central dependency, if it doesn't already exist:

    repositories {
     mavenCentral()
   }

    If your Android project uses dependencyResolutionManagement, there may be differences in how you add Maven Central dependencies.

  2. Add the following to the /Gradle Scripts/build.gradle(Module: <projectname>.app) file under dependencies to integrate the SDK into your Android project:

    • Groovy

      implementation 'io.agora.rtm:rtm-sdk:x.y.z'

      To resolve integration issues when co-integrating with the RTC SDK use:

      implementation 'io.agora.rtm:rtm-sdk-lite:x.y.z'

    • Kotlin

      implementation("io.agora.rtm:rtm-sdk:x.y.z")

      To resolve integration issues when co-integrating with the RTC SDK use:

      implementation("io.agora.rtm:rtm-sdk-lite:x.y.z")

    Replace x.y.z with the specific SDK version number, such as 2.2.8. To get the latest version number, check the Release notes.

Using CDN

  1. Download the latest version of Signaling SDK for Android.

  2. Copy all files in the sdk folder of the package to the /app/libs folder of the project.

  3. To add the SDK reference, open the project file /Gradle Scripts/build.gradle(Module: <projectname>.app) and add the following code:

    1. Add a ndk node under the default Config node, to specify the supported architectures:

      Config {
            // ...
            ndk{
                abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
            }
        }

      Supporting all architectures increases the app size. Best practice is to only add essential architectures based on your targets. For most use-cases, armeabi-v7a and arm64-v8a architectures are sufficient when releasing the Android app.

    2. Add a sourceSets node under the android node to include the jni libraries copied to the libs folder:

      android {
            // ...
            sourceSets {
                main {
                    jniLibs.srcDirs = ['libs']
                }
            }
        }

    3. To include all jar files in the libs folder as dependencies, add the following under the dependencies node:

      dependencies {
            implementation fileTree(dir: 'libs', include: ['*.jar'])
            // ...
        }

To integrate Signaling SDK version 2.2.0 or later alongside Video SDK version 4.3.0 or later, refer to handle integration issues.

Create a user interface

This section helps you create a simple user interface to explore the basic features of Signaling. Modify it according to your specific needs.

The demo interface consists of the following UI elements:

  • Input boxes for user ID, channel name, and message
  • Buttons to log in and log out of Signaling
  • Buttons to subscribe and unsubscribe from a channel
  • A button to publish a message

Sample code to create the user interface


Open the /app/res/layout/activity_main.xml file, and replace the contents with the following:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/uid"
        android:layout_width="130dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="20dp"
        android:layout_marginTop="40dp"
        android:hint="@string/uid"
        android:inputType="text"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/logout_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:onClick="onClickLogout"
        android:text="@string/logout_button"
        app:layout_constraintStart_toEndOf="@+id/login_button"
        app:layout_constraintBottom_toBottomOf="@id/uid" />

    <Button
        android:id="@+id/login_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:onClick="onClickLogin"
        android:text="@string/login_button"
        app:layout_constraintStart_toEndOf="@+id/uid"
        app:layout_constraintBottom_toBottomOf="@id/uid" />

    <EditText
        android:id="@+id/channel_name"
        android:layout_width="130dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:hint="@string/channel_name"
        android:inputType="text"
        app:layout_constraintTop_toBottomOf="@+id/uid"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/subscribe_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:onClick="onClickSubscribe"
        android:text="@string/subscribe_button"
        app:layout_constraintStart_toEndOf="@+id/channel_name"
        app:layout_constraintBottom_toBottomOf="@+id/channel_name" />

    <Button
        android:id="@+id/unsubscribe_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="5dp"
        android:onClick="onClickUnsubscribe"
        android:text="@string/unsubscribe_button"
        app:layout_constraintStart_toEndOf="@+id/subscribe_button"
        app:layout_constraintBottom_toBottomOf="@+id/subscribe_button" />

    <EditText
        android:id="@+id/msg_box"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginEnd="20dp"
        android:hint="@string/msg"
        android:inputType="text"
        android:singleLine="false"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/channel_name" />

    <Button
        android:id="@+id/send_channel_msg_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="2dp"
        android:onClick="onClickSendChannelMsg"
        android:text="@string/send_channel_msg_button"
        app:layout_constraintTop_toBottomOf="@+id/msg_box"
        app:layout_constraintEnd_toEndOf="@id/msg_box" />

    <TextView
        android:id="@+id/message_history"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="20dp"
        android:background="#eee"
        android:paddingStart="10dp"
        android:paddingEnd="10dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/send_channel_msg_button" />

</androidx.constraintlayout.widget.ConstraintLayout>

Open the app/res/values/strings.xml file and add following string resources:

<resources>
    <string name="app_name">Signaling Quickstart</string>
    <string name="login_button">Login</string>
    <string name="logout_button">Logout</string>
    <string name="subscribe_button">Subscribe</string>
    <string name="unsubscribe_button">Unsubscribe</string>
    <string name="send_channel_msg_button">Publish message</string>
    <string name="uid">User ID</string>
    <string name="msg">Message content</string>
    <string name="channel_name">Channel name</string>
    <string name="app_id">your_appid</string>
    <string name="token">your_token</string>
</resources>

Implement Signaling

A complete code sample that implements the basic features of Signaling is presented here for your reference. To use the sample code, copy the following lines into the /app/src/main/java/com/example/<projectname>/MainActivity file and replace <projectname> in package com.example.<projectname> with the name of your project.

Complete sample code for Signaling

package com.example.<projectname>;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import io.agora.rtm.*;

public class JavaActivity extends AppCompatActivity {
    private EditText etUserId;
    private EditText etChannelName;
    private EditText etMessageContent;
    private TextView mMessageHistory;

    private RtmClient mRtmClient;

    private final RtmEventListener eventListener = new RtmEventListener() {
        @Override
        public void onMessageEvent(MessageEvent event) {
            String text = "Message received from " + event.getPublisherId()
                    + ", Message: " + event.getMessage().getData();
            writeToMessageHistory(text);
        }

        @Override
        public void onPresenceEvent(PresenceEvent event) {
            String text = "Received presence event, user: " + event.getPublisherId()
                    + ", Event: " + event.getEventType();
            writeToMessageHistory(text);
        }

        @Override
        public void onLinkStateEvent(LinkStateEvent event) {
            String text = "Connection state changed to " + event.getCurrentState()
                    + ", Reason: " + event.getReason();
            writeToMessageHistory(text);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void onClickLogin(View v) {
        etUserId = findViewById(R.id.uid);
        String userId = etUserId.getText().toString();
        String token = getString(R.string.token);
        if (createClient(userId)) {
            login(token);
        }
    }

    public void onClickLogout(View v) {
        logout();
    }

    public void onClickSubscribe(View v) {
        etChannelName = findViewById(R.id.channel_name);
        String channelName = etChannelName.getText().toString();
        subscribe(channelName);
    }

    public void onClickUnsubscribe(View v) {
        etChannelName = findViewById(R.id.channel_name);
        String channelName = etChannelName.getText().toString();
        unsubscribe(channelName);
    }

    public void onClickSendChannelMsg(View v) {
        etChannelName = findViewById(R.id.channel_name);
        String channelName = etChannelName.getText().toString();

        etMessageContent = findViewById(R.id.msg_box);
        String message = etMessageContent.getText().toString();
        publishMessage(channelName, message);
    }

    private boolean createClient(String userId) {
        if (userId.isEmpty()) {
            showToast("Invalid userId");
            return false;
        }

        try {
            RtmConfig config = new RtmConfig.Builder(getString(R.string.app_id), userId)
                    .eventListener(eventListener)
                    .build();
            mRtmClient = RtmClient.create(config);
            return true;
        } catch (Exception e) {
            showToast("Error creating RTM client.");
            return false;
        }
    }

    private void login(String token) {
        if (mRtmClient == null) {
            showToast("RTM client is null");
            return;
        }

        mRtmClient.login(token, new ResultCallback<>() {
            @Override
            public void onSuccess(Void responseInfo) {
                writeToMessageHistory("Successfully logged in to Signaling!");
            }

            @Override
            public void onFailure(ErrorInfo errorInfo) {
                writeToMessageHistory("Failed to log in to Signaling: " + errorInfo);
            }
        });
    }

    private void logout() {
        if (mRtmClient == null) {
            showToast("RTM client is null");
            return;
        }

        mRtmClient.logout(new ResultCallback<>() {
            @Override
            public void onSuccess(Void responseInfo) {
                writeToMessageHistory("Successfully logged out.");
            }

            @Override
            public void onFailure(ErrorInfo errorInfo) {
                writeToMessageHistory("Failed to log out: " + errorInfo);
            }
        });
    }

    private void subscribe(String channelName) {
        if (mRtmClient == null) {
            showToast("RTM client is null");
            return;
        }

        SubscribeOptions options = new SubscribeOptions();
        options.setWithMessage(true);

        mRtmClient.subscribe(channelName, options, new ResultCallback<>() {
            @Override
            public void onSuccess(Void responseInfo) {
                writeToMessageHistory("Successfully subscribed to the channel!");
            }

            @Override
            public void onFailure(ErrorInfo errorInfo) {
                writeToMessageHistory("Failed to subscribe to the channel: " + errorInfo);
            }
        });
    }

    private void unsubscribe(String channelName) {
        if (mRtmClient == null) {
            showToast("RTM client is null");
            return;
        }

        mRtmClient.unsubscribe(channelName, new ResultCallback<>() {
            @Override
            public void onSuccess(Void responseInfo) {
                writeToMessageHistory("Successfully unsubscribed from the channel!");
            }

            @Override
            public void onFailure(ErrorInfo errorInfo) {
                writeToMessageHistory("Failed to unsubscribe from the channel: " + errorInfo);
            }
        });
    }

    private void publishMessage(String channelName, String message) {
        if (mRtmClient == null) {
            showToast("RTM client is null");
            return;
        }

        PublishOptions options = new PublishOptions();
        options.setCustomType("");

        mRtmClient.publish(channelName, message, options, new ResultCallback<>() {
            @Override
            public void onSuccess(Void responseInfo) {
                writeToMessageHistory("Message sent to channel " + channelName + ": " + message);
            }

            @Override
            public void onFailure(ErrorInfo errorInfo) {
                writeToMessageHistory("Failed to send message to channel " + channelName + ": " + errorInfo);
            }
        });
    }

    private void writeToMessageHistory(String record) {
        if (mMessageHistory == null) {
            mMessageHistory = findViewById(R.id.message_history);
        }
        mMessageHistory.append("- " + record + "
");
    }

    private void showToast(String text) {
        Toast.makeText(this, text, Toast.LENGTH_SHORT).show();
    }
}

Follow the implementation steps to understand the core API calls in the sample code or use the snippets in your own code.

Import Agora classes

To use Signaling APIs in your project, import the relevant Agora classes and interfaces:

import io.agora.rtm.*;

Initialize the Signaling engine

Before calling any other Signaling SDK API, initialize an RtmClient object instance.

private boolean createClient(String userId) {
    if (userId.isEmpty()) {
        showToast("Invalid userId");
        return false;
    }
    try {
        RtmConfig config = new RtmConfig.Builder(getString(R.string.app_id), userId)
                .eventListener(eventListener)
                .build();
        mRtmClient = RtmClient.create(config);
        return true;
    } catch (Exception e) {
        showToast("Error creating RTM client.");
        return false;
    }
}

Add an event listener

The event listener enables you to implement the processing logic in response to Signaling events. Use the following code to handle event notifications or display received messages:

private RtmEventListener eventListener = new RtmEventListener() {
    @Override
    public void onMessageEvent(MessageEvent event) {
        String text = "Message received from " + event.getPublisherId()
                + " Message: " + event.getMessage().getData();
        writeToMessageHistory(text);
    }

    @Override
    public void onPresenceEvent(PresenceEvent event) {
        String text = "Received presence event, user: " + event.getPublisherId()
                + " Event: " + event.getEventType();
        writeToMessageHistory(text);
   }

    @Override
    public void onLinkStateEvent(LinkStateEvent event) {
        String text = "Connection state changed to " + event.getCurrentState()
                + ", Reason: " + event.getReason();
        writeToMessageHistory(text);
    }
};

Log in to Signaling

To connect to Signaling and access Signaling network resources, such as sending messages, and subscribing to channels, call login.

During a login operation, the client attempts to establish a connection with Signaling. Once the connection is established, the client transmits heartbeat information to the Signaling server at fixed intervals to keep the client active until the client actively logs out or is disconnected. The connection is interrupted when timeout occurs. During this period, users may freely access the Signaling network resources subject to their own permissions and usage restrictions.

private void login(String token) {
    if (mRtmClient == null) {
        showToast("RTM client is null");
        return;
    }
    mRtmClient.login(token, new ResultCallback<>() {
        @Override
        public void onSuccess(Void responseInfo) {
            writeToMessageHistory("Successfully logged in to Signaling!");
        }
        @Override
        public void onFailure(ErrorInfo errorInfo) {
            writeToMessageHistory("Failed to log in to Signaling: " + errorInfo);
        }
    });
}

To confirm that login is successful, use the login return value, or listen to the onLinkStateEvent event notification which provides the error code and reason for the login failure. When performing a login operation, the client's network connection state is CONNECTING. After a successful login, the state is updated to CONNECTED.

Best practice

To continuously monitor the network connection state of the client, best practice is to continue to listen for onLinkStateEvent notifications throughout the life cycle of the application. For further details, see Event listeners.

After a user successfully logs into Signaling, the application's PCU increases, which affects your billing data.

Publish a message

To distribute a message to all subscribers of a message channel, call publish. The following code sends a string type message.

private void publishMessage(String channelName, String message) {
    if (mRtmClient == null) {
        showToast("RTM client is null");
        return;
    }
    PublishOptions options = new PublishOptions();
    options.setCustomType("");
    mRtmClient.publish(channelName, message, options, new ResultCallback<>() {
        @Override
        public void onSuccess(Void responseInfo) {
            writeToMessageHistory("Message sent to channel " + channelName + ": " + message);
        }
        @Override
        public void onFailure(ErrorInfo errorInfo) {
            writeToMessageHistory("Failed to send message to channel " + channelName + ": " + errorInfo);
        }
    });
}

Before calling publish to send a message, serialize the message payload as a string.

Subscribe and unsubscribe

To subscribe to a channel, call subscribe. When you subscribe to a channel, you receive all messages published to the channel.

private void subscribe(String channelName) {
    if (mRtmClient == null) {
        showToast("RTM client is null");
        return;
    }
    SubscribeOptions options = new SubscribeOptions();
    options.setWithMessage(true);
    mRtmClient.subscribe(channelName, options, new ResultCallback<>() {
        @Override
        public void onSuccess(Void responseInfo) {
            writeToMessageHistory("Successfully subscribed to the channel!");
        }
        @Override
        public void onFailure(ErrorInfo errorInfo) {
            writeToMessageHistory("Failed to subscribe to the channel: " + errorInfo);
        }
    });
}

When you no longer need to receive messages from a channel, call unsubscribe to unsubscribe from the channel:

private void unsubscribe(String channelName) {
    if (mRtmClient == null) {
        showToast("RTM client is null");
        return;
    }
    mRtmClient.unsubscribe(channelName, new ResultCallback<>() {
        @Override
        public void onSuccess(Void responseInfo) {
            writeToMessageHistory("Successfully unsubscribed from the channel!");
        }
        @Override
        public void onFailure(ErrorInfo errorInfo) {
            writeToMessageHistory("Failed to unsubscribe from the channel: " + errorInfo);
        }
    });
}

For more information about subscribing and sending messages, see Message channels and Stream channels.

Log out of Signaling

When a user no longer needs to use Signaling, call logout. Logging out means closing the connection between the client and Signaling. The user is automatically logged out or unsubscribed from all message and stream channels. Other users in the channel receive an onPresenceEvent notification of the user leaving the channel.

private void logout() {
    if (mRtmClient == null) {
        showToast("RTM client is null");
        return;
    }
    mRtmClient.logout(new ResultCallback<>() {
        @Override
        public void onSuccess(Void responseInfo) {
            writeToMessageHistory("Successfully logged out.");
        }
        @Override
        public void onFailure(ErrorInfo errorInfo) {
            writeToMessageHistory("Failed to log out: " + errorInfo);
        }
    });

    // Release resources
    mRtmClient.release();
}

Test Signaling

Take the following steps to test the sample code:

  1. Use the Token Builder to generate a Signaling token:

    1. Select Signaling from the Agora products dropdown.
    2. Fill in your app ID and app certificate from Agora Console. Leave the remaining fields blank.
    3. Click Generate Token.

  2. In strings.xml, replace the values for app_id and token with your app ID and generated token.

  3. Enable developer options on your Android test device. Turn on USB debugging, connect the Android device to your development machine through a USB cable, and check that your device appears in the Android device options.

  4. In Android Studio, click Sync Project with Gradle Files to resolve project dependencies and update the configuration.

  5. After synchronization is successful, click ▶️. Android Studio starts compilation. After a few moments, the app is installed and launched on your Android device.

  6. Use the device as the receiving end and perform the following operations:

    1. Enter your User ID and click Login.
    2. Enter the Channel name and click Subscribe .

  7. On a second Android device, repeat the previous steps to install and launch the app. Use this device as the sending end.

    1. Enter a different User ID and click Login.
    2. Enter the same Channel name.
    3. Type a message and click Publish message.

  8. Swap the sending and receiving device roles and repeat the previous steps.

    Congratulations! You have successfully integrated Signaling into your project.

Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

Token authentication

In this guide you retrieve a temporary token from a Token Builder. To understand how to create an authentication server for development purposes, see Secure authentication with tokens.

Sample projects

Agora provides the following open source sample projects on GitHub for your reference.

Java

Kotlin

Download the projects or view the source code for more detailed examples.

API reference

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