subscribeRetryOnInvalidName

Subscribe Retry on Invalid Name

This example demonstrates utilizing the maintainConnectionOnSubscribeErrors configuration property of a subscriber in order to maintain the WebSocket connection upon errors from the subscribe request after intializing.

When you request to init a WebRTC-based subscriber, it establshes a WebSocket connection over which server events are notified. When you subsequently request to subscribe, there are a series of WebSocket requests that lead to the ICE negotiation process and - when successful - establish a PeerConnection and exchange the MediaStream asset for playback.

By default, if the subscribe request fails, the SDK will also shutdown the previously established WebSocket connection. By setting the maintainConnectionOnSubscribeErrors to true, it allows you - as a developer - to handle failure events from the subscribe event and maintain the WebSocket to try a subscribe request again at a later time.

Please refer to the Basic Subscriber Documentation to learn more about the basic setup.

Example Code

• index.html
• index.js

These examples use the WebRTC-based Subscriber implementation from the Red5 Pro HTML SDK. However.

Running the Example

In this example we will utilize the maintainConnectionOnSubscribeErrors configuration proeprty in tandem with an event listener for the Subscribe.InvalidName event to enable a Retry button to attempt a subscribe request again.

1. Check the settings and stream1 field value in particular.
2. Ensure that you are not currently publishing a stream with the stream1 value.

Setting maintainConnectionOnSubscribeErrors

var config = Object.assign(
  {
    maintainConnectionOnSubscribeErrors: true,
  },
  configuration,
  defaultConfiguration
)

Listening for Subscribe.InvalidName

The Retry button element is disabled by default, and enabled on recognition of the Subscribe.InvalidName event.

var subscriber = new red5prosdk.WHEPClient()
subscriber.on(
  red5prosdk.SubscriberEventTypes.SUBSCRIBE_INVALID_NAME,
  function () {
    enableRetryButton()
  }
)
disableRetryButton()

Request to initialize

The configuration is passed in the init request which - upon successful establishment of a WebSocket connection - adds lifecycle event handlers and requests to subscribe.

targetSubscriber = new WHEPClient()
targetSubscriber
  .init(config)
  .then(function () {
    streamTitle.innerText = configuration.stream1
    // Subscribe to events.
    targetSubscriber.on('*', onSubscriberEvent)
    return targetSubscriber.subscribe()
  })
  .then(function () {
    onSubscribeSuccess()
  })
  .catch(function (error) {
    var jsonError =
      typeof error === 'string' ? error : JSON.stringify(error, null, 2)
    console.error('[Red5ProSubscriber] :: Error in subscribing - ' + jsonError)
    onSubscribeFail(jsonError)
  })

Retry

A failure in the subscribe request will enable the Retry button which has a click event handler to make another attempt to the subscribe request:

retryButton.addEventListener('click', function () {
  statusField.innerText = 'Retrying subscription...'
  if (targetSubscriber) {
    disableRetryButton()
    targetSubscriber
      .subscribe()
      .then(function () {
        onSubscribeSuccess()
      })
      .catch(function (error) {
        var jsonError =
          typeof error === 'string' ? error : JSON.stringify(error, null, 2)
        console.error(
          '[Red5ProSubscriber] :: Error in subscribing - ' + jsonError
        )
        onSubscribeFail(jsonError)
      })
  }
})

If you start a publishing session with the target stream name in between a failure of the subscribe request and a requestt to retry, the subscription and subsequent playback will occur.