AJAX Periodic Update Mixin

Here we have moved the "AJAX periodic update" functionality into a mixin that can be used with any Zone.
serverTime: Thu Dec 14 13:31:56 EST 2017
The ZonePeriodicUpdater mixin on this page has a maxUpdates parameter. If we didn't need that parameter then we could use Tapestry's ZoneRefresh mixin instead.

References: Ajax and Zones, Zone, Component Mixins, ComponentResources, JavaScriptSupport, ClientElement, @Inject, @InjectContainer, @InjectComponent, JavaScript Timing Events, t5/core/zone.

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- We need a doctype to allow us to use special characters like &nbsp; 
     We use a "strict" DTD to make IE follow the alignment rules. -->
     
<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_4.xsd">
<body class="container">
    <h3>AJAX Periodic Update Mixin</h3>

    <noscript class="js-required">
        ${message:javascript_required}
    </noscript>     

    Here we have moved the "AJAX periodic update" functionality into a mixin that can be used with any Zone.

    <div class="eg">
        <t:zone t:id="timeZone" id="timeZone" t:mixins="ZonePeriodicUpdater" 
            ZonePeriodicUpdater.event="refreshTimeZone" ZonePeriodicUpdater.frequencySecs="3" ZonePeriodicUpdater.maxUpdates="4">
            serverTime:  ${serverTime}
        </t:zone>
    </div>
    
    The ZonePeriodicUpdater mixin on this page has a maxUpdates parameter. If we didn't need that parameter then we could use Tapestry's 
    <a href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/mixins/ZoneRefresh.html">ZoneRefresh</a> mixin instead.<br/><br/>

    References: 
    <a href="http://tapestry.apache.org/ajax-and-zones.html">Ajax and Zones</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/corelib/components/Zone.html">Zone</a>,
    <a href="http://tapestry.apache.org/component-mixins.html">Component Mixins</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/ComponentResources.html">ComponentResources</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/services/javascript/JavaScriptSupport.html">JavaScriptSupport</a>, 
    <a href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ClientElement.html">ClientElement</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/ioc/annotations/Inject.html">@Inject</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/annotations/InjectContainer.html">@InjectContainer</a>, 
    <a href="http://tapestry.apache.org/5.4/apidocs/org/apache/tapestry5/annotations/InjectComponent.html">@InjectComponent</a>, 
    <a href="http://www.w3schools.com/js/js_timing.asp">JavaScript Timing Events</a>, 
    <a href="http://tapestry.apache.org/5.4/coffeescript/zone.html">t5/core/zone</a>.<br/><br/> 
    
    <t:pagelink page="Index">Home</t:pagelink><br/><br/>
    
    <t:tabgroup>
        <t:sourcecodetab src="/web/src/main/java/jumpstart/web/pages/examples/ajax/AjaxPeriodicUpdateMixin.tml"/>
        <t:sourcecodetab src="/web/src/main/java/jumpstart/web/pages/examples/ajax/AjaxPeriodicUpdateMixin.java"/>
        <t:sourcecodetab src="/web/src/main/resources/META-INF/assets/css/examples/js.css"/>
        <t:sourcecodetab src="/web/src/main/java/jumpstart/web/mixins/ZonePeriodicUpdater.java"/>
        <t:sourcecodetab src="/web/src/main/resources/META-INF/modules/zone-periodic-updater.js"/>
    </t:tabgroup>
</body>
</html>


package jumpstart.web.pages.examples.ajax;

import java.util.Date;

import org.apache.tapestry5.annotations.Import;
import org.apache.tapestry5.annotations.InjectComponent;
import org.apache.tapestry5.corelib.components.Zone;
import org.apache.tapestry5.ioc.annotations.Inject;
import org.apache.tapestry5.services.Request;
import org.apache.tapestry5.services.ajax.AjaxResponseRenderer;

@Import(stylesheet = "css/examples/js.css")
public class AjaxPeriodicUpdateMixin {

    // Generally useful bits and pieces

    @InjectComponent
    private Zone timeZone;

    @Inject
    private AjaxResponseRenderer ajaxResponseRenderer;

    @Inject
    private Request request;

    // The code

    void onRefreshTimeZone() {
        if (request.isXHR()) {
            ajaxResponseRenderer.addRender(timeZone);
        }
    }

    public Date getServerTime() {
        return new Date();
    }
}


.eg {
                margin: 20px 0;
                padding: 14px;
                color: #888;
                border: 1px solid #ddd;
                border-radius: 6px;
                -webkit-border-radius: 6px;
                -mox-border-radius: 6px;
}

.js-required {
                color: red;
                display: block;
                margin-bottom: 14px;
}

.js-recommended {
                color: red;
                display: block;
                margin-bottom: 14px;
}


/**
 * A simple mixin for attaching javascript to a Zone that periodically issues an AJAX request to update the Zone.
 * Loosely based on Tapestry's ZoneRefresh.
 */
package jumpstart.web.mixins;

import org.apache.tapestry5.BindingConstants;
import org.apache.tapestry5.ComponentResources;
import org.apache.tapestry5.annotations.InjectContainer;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.corelib.components.Zone;
import org.apache.tapestry5.ioc.annotations.Inject;
import org.apache.tapestry5.services.javascript.JavaScriptSupport;

public class ZonePeriodicUpdater {

    // Parameters

    @Parameter(required = true, defaultPrefix = BindingConstants.LITERAL)
    private String event;

    @Parameter
    private Object[] context;

    @Parameter(defaultPrefix = BindingConstants.LITERAL, required = true)
    private int frequencySecs;

    @Parameter(defaultPrefix = BindingConstants.LITERAL, required = true)
    private int maxUpdates;

    // Useful bits and pieces

    @Inject
    private ComponentResources componentResources;

    @Inject
    private JavaScriptSupport javaScriptSupport;

    /**
     * The element we attach ourselves to, which must be a Zone
     */
    @InjectContainer
    private Zone zone;

    // The code

    void afterRender() {
        String eventURL = componentResources.createEventLink(event, context).toAbsoluteURI();

        javaScriptSupport.require("zone-periodic-updater")
                .with(zone.getClientId(), eventURL, frequencySecs, maxUpdates);
    }

}


// For a zone (zoneElementId), periodically issues an AJAX request (eventURL) to update it.

define(["jquery", "t5/core/zone"], function($, zoneManager) {

    return function(zoneElementId, eventURL, frequencySecs, maxUpdates) {

        var frequencyMillis = frequencySecs * 1000;
        var updatesCount = 0;

        var interval = setInterval(updateZone, frequencyMillis);

        function updateZone() {
            if (updatesCount++ < maxUpdates) {
                // Update the zone.
                zoneManager.deferredZoneUpdate(zoneElementId, eventURL);
            }
            else {
                // Stop updating.
                clearInterval(interval);
            }
        }
    }

});