Vaadin Spring Security

Question

I have been working from an example I found, here's the link to the Git repo:

https://github.com/basakpie/vaadin8-spring-security-sample

It works great, it's just what I need, except for one thing: I need Server Push.

Here's what I've done so far:

• added the Vaadin Push dependency

• added the following lines to the start of the MainUI.init() method:

  getPushConfiguration().setTransport(Transport.WEBSOCKET);
  getPushConfiguration().setPushMode(PushMode.AUTOMATIC);
  

• Added the following fields to the MainUI class:

  Label time = new Label();
  Timer timer;
  

• Added the following method to the MainUI class:

  private void updateTime() {
    access(() -> time.setValue(String.format("The server-side time is %s",  LocalTime.now().format(DateTimeFormatter.ofPattern("HH:mm:ss")))));
  }
  

• Finally, added the following to the end of the MainUI.init() method:

  timer = new Timer();
  timer.schedule(new TimerTask() {
      @Override
      public void run() {
          updateTime();
      }
  }, 1000L, 1000L);
  

It mostly works. I am able to see the current system time updating every second. But when I hit refresh in the browser, the application just hangs with the vaadin loading spinner. There are no error messages.

I have tried the following alternatives:

Adding the method

public void attach() {
    getPushConfiguration().setTransport(Transport.WEBSOCKET);
    getPushConfiguration().setPushMode(PushMode.AUTOMATIC);
}

and removing the getPushConfiguration lines from init()

This solves the hanging problem, but the push does not work - no errors, just the time is not displayed at all.

I also tried adding a @Push annotation to MainUI. This results in the same behaviour as before - freezing on refresh.

How can I fix this? Any suggestions would be welcome.

Answer 1

Try out the below procedure:

1. Add @Push to the MainUI.java file

   @Push(transport = Transport.WEBSOCKET,value = PushMode.AUTOMATIC)

2. Instead of :

   getPushConfiguration().setTransport(Transport.WEBSOCKET); getPushConfiguration().setPushMode(PushMode.AUTOMATIC);

3. Add @PreDestroy to exit the timer when you navigate from the mainUI

   @PreDestroy void destroy() { timer.cancel(); }

Find the complete revised code HERE

https://gist.github.com/cansoftinc/351452ee0e616d353519f147c4a961ba

Answer 2

I Had exactly the same problem and my solution to this was to implement the vaadin servlet. Check this for more information.