vaadin 7 - transaction listener

Vaadin 6 / 7 / 8
1

Hi,

i am looking for a way to track the begin and end of a transaction to set a reference to a ThreadLocal variable.
Vaadin 6 offered the transaction listener. It allowed me to do initialization when a transaction was started and clean up if it was ended.

ThreadLocalHelper:
trxStarts(){
MyService.setCurrent(instance)
}

txnEnds() {
MyService.setCurrent(null)
}

But i can not find a way to do so in vaadin 7? Is there a replacement for it?

Thanks Florian

2

@vaadin-core-team: Any ideas?

Thanks Florian

3

What exactly do you want to do with it? The normal use case was that you wanted to store the application reference into a place that you can access it statically, like MyApplication.get();. If this is what you are looking for, there is now UI.getCurrent(); built in into Vaadin without the need of transaction listeners.

4

I would like to store one of my own objects to a ThreadLocal variable.
Then i can access it everywhere from the code as long as i am in an active request.

With vaadin 6 that was simple.


TransactionListener {
   trancationStart() {
       Context.foo = someValue
   }  

   transactionEnd() {
      Context.foo = null
   }

A downcast of UI is not an option in my case.

Thanks, Florian

5

Hi Florian,

Take a look at VaadinSession.getCurrent().set/getAttribute(). That is one way you can store it.

6

How about if we want to set logging MDC values unique to each request thread? Certainly we can’t use the session object in that case: Log4J’s MDC knows nothing about Vaadin.

In general, there may be thread locals that are not under our control, so we can’t resort to a Session. I suppose we could hijack Vaadin’s servlet, but then this feels more and more like a regression.

Another use case is one in which we enable maintenance mode in an application and we want our users to immediately get a different screen. We used to decide this on transactionStart. How can we decide it in Vaadin 7?

7

Has this been awnsered? Im having the exact same issue (MDC logging) and cant figure out the proper place to implemt it.

8

Also - Ive tried

VaadinSession.getCurrent().addRequestHandler(...)

But the request handler is only called for non UI requests, which isnt enough to correctly setup the logging MDC for all threads.