publishSharedObject

Publish & Subscribe Shared Object

This example demonstrates the use of Remote Shared Objects, which provides a mechanism to share and persist information across mutiple clients in real time, as well as sending messages to all clients that are connected to the object.

Example Code

• index.html
• index.js

Setup

Use of Shared objects requires an active stream - either publishing or subscribing. The content of the stream isn't important to the shared object itself, even a muted audio-only stream will be enough. Also, which stream you are connected to isn't important to which shared object you access, meaning that clients across multiple streams can use the same object, or there could be multiple overlapping objects in the same stream.

To run the test, you will need at least two clients running the Shared Object example. This example searches active streams for the stream name set as stream1.

Connection

Shared objects require a successfully started stream to transmit data.

Instantiating a new Red5ProSharedObject requires a name and the connection used for your stream. After that it will connect and notify the object set as its client that it has connected successfully.

var so = new red5pro.Red5ProSharedObject('sharedChatTest', publisher);
so.on(red5pro.SharedObjectEventTypes.PROPERTY_UPDATE, handlePropertyUpdate);
so.on(red5pro.SharedObjectEventTypes.METHOD_UPDATE, handleMethodUpdate);

index.js #96

To disconnect from a SharedObject, simply call close on the instance.

Events

The SharedObject instance dispatches the following events:

• Connect.Success, accessible on SDK root at SharedObjectEventTypes.CONNECT_SUCCESS.
• Connect.Failure, accessible on SDK root at SharedObjectEventTypes.CONNECT_FAILURE.
• SharedObject.PropertyUpdate, accessible on SDK root at SharedObjectEventTypes.PROPERTY_UPDATE.
• SharedObject.MethodUpdate, accessible on SDK root at SharedObjectEventTypes.METHOD_UPDATE.

Name	Description
Connect.Success	Successful connection of SharedObject on the publisher or subscriber instance.
Connect.Failure	Failure in connection of SharedObject on the publisher or subscriber instance.
SharedObject.PropertyUpdate	Update to a peristed property on the remote SharedObject.
SharedObject.MethodUpdate	Remote SharedObject invocation of method to be received on connected clients.

Persistent Information

Remote Shared Objects use JSON for transmission, meaning that its structure is primarily up to your discretion. The base object will always be a dictionary with string keys, while values can be strings, numbers, booleans, arrays, or other dictionaries - with the same restriction on sub-objects.

This example simply uses a number to keep a count of how many people are connected to the object. As seen in the PROPERTY_UPDATE handler, value can be accessed from the object by name, and set using setProperty:

so.on(red5pro.SharedObjectEventTypes.PROPERTY_UPDATE, function (event) {
  if (event.data.hasOwnProperty('count')) {
    appendMessage('User count is: ' + event.data.count + '.');
    if (!hasRegistered) {
      hasRegistered = true;
      so.setProperty('count', parseInt(event.data.count) + 1);
    }
  }
  else if (!hasRegistered) {
    hasRegistered = true;
    so.setProperty('count', 1);
  }
});

index.js #107

Messages

The Shared Object interface also allows sending messages to other people watching the object. By sending a Object through the send method, that object will be passed to all the listening clients that implement the specified call.

function sendMessageOnSharedObject (message) {
  so.send('messageTransmit', {
    user: configuration.stream1,
    message: message
  });
}

index.js #129

Like with the parameters of the object, as long as the Object sent parses into JSON, the structure of the object is up to you, and it will reach the other clients in whole as it was sent.

In this example, we are marking the message object as type messageTransmit with data related ot the user sending the message and a message String.

In the event handler for messages, this example then invokes that method name of messageTransmit on the callback client:

// Invoked from METHOD_UPDATE event on Shared Object instance.
function messageTransmit (message) { // eslint-disable-line no-unused-vars
  soField.value = ['User "' + message.user + '": ' + message.message, soField.value].join('\n');
}
...
so.on(red5pro.SharedObjectEventTypes.METHOD_UPDATE, function (event) {
  soCallback[event.data.methodName].call(null, event.data.message);
});

index.js #122