AttributesSync Class

public abstract class AttributesSync : CommunicationBridgeUID

// By inheriting from AttributesSync, we get access to attributes and methods for controlling synchronization
// of methods and fields between clients in a room.
public class MyAttributesSyncClass : AttributesSync
{
       // By using the SynchronizableField attribute, the field will be synchronized between other clients
       // in the same room automatically.
       [SynchronizableField]
       public string MyString;
}

public class MessageAll : AttributesSync
{
    private int _messageMethodID;

    private void Start()
    {
        // Get the method's ID once.
        _messageMethodID = GetMethodAttributeId(nameof(Message));
    }

    public void SendMessage()
    {
        // Invoke method by id.
        BroadcastRemoteMethod(_messageMethodID, "Hello, world!");

        // Alternatively, you can invoke using the SynchronizableMethod's name. This method of calling the
        // SynchronizableMethod is less performant as it has to look through all SynchronizableMethod's rather
        // than calling it directly using the ID.
        // BroadcastRemoteMethod(nameof(Message), "Hello, world!");
    }

    // The SynchronizableMethod attribute marks the method as available for invocation from
    // AttributesSync behavior.
    [SynchronizableMethod]
    private void Message(string msg)
    {
        // The message will now be printed to all the clients' log in the room.
        Debug.Log(msg);
    }
}

public class PlayAudioSync : AttributesSync
{
    // Reference to AudioSource.
    public AudioSource AudioSource;

    // The public method that we call in an event or from external scripts.
    public void Play()
    {
        // When no argument is provided, ID defaults to 0.
        // Calls the method on all clients, including the sending client.
        BroadcastRemoteMethod();
    }

    // We define our synced method here.
    // As we only define one in this script, we know this one have index 0.
    [SynchronizableMethod]
    private void PlayRemote()
    {
        AudioSource.Play();
    }
}

public class Message : AttributesSync
{
    public void SendMessageToUser(ushort userID, string message)
    {
        // Calls the function on a different client.
        // As there is only one SynchronizableMethod in this script, the method ID will always be 0.
        // So we will just use id 0 here instead of using the nameof method.
        InvokeRemoteMethod(0, userID, message);
    }

    public void SendMessageToUsers(ushort[] userIDs, string message)
    {
        // Calls method by index.
        InvokeRemoteMethod(0, userIDs, message);
    }

    // Because this is the first method defined, we know its index is 0. The next one would have index of 1.
    [SynchronizableMethod]
    private void Message(string msg)
    {
        // This message will not be printed on the client(s) that has matching id(s).
        Debug.Log(msg);
    }
}