Why is event threads deprecated?

answered 2014-10-27 17:03:05 +0800

gargamel25
41 ● 2

updated 2014-10-27 20:52:34 +0800

What I understood....

It's only deprecated, so you can still use it.

It's not a best practice, because if you create another thread from it(a new modal window for example) the thread serving your request will be blocked until you close the modal window.

Now knowing the default maxThreads value for tomcat 6 is 200 See : tomcat.apache.org/tomcat-6.0-doc/config/executor.html

you can see how fast 200 users who keep a opened modal window can make the server not utilizable anymore, so it won't accept any new request.

If you use disable-event-thread = false

you can have the following command:

@Command 
public void advancedSearch() {
    Window win = (Window)Executions.createComponents("/pages/new_account.zul", null, null);
    win.doModal();
    this.newAccount = (Account) win.getAttribute("account");

}

The current thread obtained from the server thread pool is blocked until you fill all the data needed for new account. So request thread is waiting at this line win.doModal().

If you have worked with swing for example, you know it's a practice there to create modals this way, but there's only one user using the app. In a web application you should not block the request until user fills a form...

If you use disable-event-thread = true which is the default, the code will be executed right away, but win.getAttribute("account") will always return null. So you need to find another solution to get the result obtained after the modal window closes.

Hope this helps.

answered 2015-05-26 01:48:30 +0800

martindk
19 ● 1

This thread (pun intended) just simply makes me angry. This is a clear indication that the ZK developers have simply lost touch with the needs of those who use this otherwise awesome framework. The notion that one can develop a serious web application without support for modal dialogs is ludicrous. We have built an entire open source electronic medical record and order entry system with ZK serving thousands of concurrent users and have not encountered the performance limits that you suggest. If you do remove support for event threads, we will move on to another technology. We simply will have no choice. Really, guys, pay attention to what your customers need.

answered 2016-02-05 11:54:34 +0800

cor3000
6280 ● 2 ● 7

just for fun and example how "nice" things can be using some java 8 features

@Listen("onClick=#personSaveButton")
public void onSavePerson(){
    confirm("Confirm Save (Y/N)", this.selectedPerson, this::savePerson, this::cancelPerson); 
}

public void savePerson(Person data) {
    //do some save
}

public void cancelPerson(Person data) {
    //do some cancel
}

public static <T>void confirm(String message, T data, Consumer<T> yesHander, Consumer<T> noHandler) {
    Messagebox.show(message, new Messagebox.Button[] {YES, NO}, ce -> {
        if(YES == ce.getButton()) {
            yesHander.accept(data);
        } else if (NO == ce.getButton()){
            noHandler.accept(data);
        }
    });
}