Caution

This is the documentation for the current development branch of the CometVisu. It is possible that some of the described features are not yet available in the current release.

Also there might be lots of errors in this documentation as some parts of the content have been translated by an online translation service.

Server sent events (SSE)

Reading inquiries

At Server sent events, a one-time read connection is established. Initially, the backend sends all the requested values once, then only changed values.

Hint

The browser automatically takes care of the restoration of the connection in case of abortions. Therefore, the internal Watchdog is usually not used in SSE.

However, the browser must support this technology. An overview of the supported browsers is provided by Caniuse.

Writing inquiries

When a new value is to be sent to the backend (because, for example, the user has serviced a widget), a new request that is completely independent of the read requests is sent to the backend. Here, the backend only confirms the successful receipt of the request, new values are always sent only via the read requests.