Properly using Primefaces p:poll saving network traffic

example onstart handler.js

function onStartPoll() {
    if ($("#fragment-group-form\\:promo-messages .ui-messages-info").is(":visible")) {
        // Suspend polling while the promotion message appears (to save network traffic)
        PF("poll").stop();
        var timer = setInterval(function() {
            if (! $("#fragment-group-form\\:promo-messages .ui-messages-info").is(":visible")) {
                // The promotion message is closed; Restart polling
                PF("poll").start();
                clearInterval(timer);
            }
        }, 2000);
    }
}

example view.md

<h:form id="fragment-group-form">
    <p:messages id="promo-messages" escape="false" globalOnly="false" showDetail="true" closable="true"/>

    <p:poll widgetVar="poll" interval="5" autoStart="true" onstart="onStartPoll();" listener="#{pollController.test}" update="promo-messages" />    
    ...
</h:form>

Properly using Primefaces p:poll saving network traffic.java

package com.civilizer.web.controller;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;

import com.civilizer.web.view.*;

@ManagedBean
@ViewScoped
public final class PollController {

    private static final String PROMOTION_MESSAGE_CLIENT_ID = "fragment-group-form:promo-messages";

    public void test() {
        ViewUtil.addMessage(PROMOTION_MESSAGE_CLIENT_ID, "Testing...", "hello", null);
    }

}

http://www.primefaces.org/docs/vdl/6.0/core/primefaces-p/poll.html

• Problem Discussion
  • This will show a banner message in the browser by polling to the server at a regular interval
  • Basically it works, but not so efficient in terms of network bandwidth;
  • While the banner appears, the polling will continue ending up doing nothing useful; usually this is a waste of network traffic
• Workaround
  • onStartPoll is called in the client when the poll request is about to start;
  • And it checks if the banner is visible and if so, it will suspend the polling to save some network bandwidth;
  • It also installs a recurring timer and in that timer callback, it will check the banner is closed by the user;
  • If it detects the banner is closed then it restarts the polling