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Ajax support is included in many built-in components and component mixins via the async parameter (in Tapestry 5.4+) and the zone parameter (for earlier versions). Here we use an EventLink component to trigger an Ajax update of another area of the page:

<t:eventlink event="updateTime" async="true">update</t:eventlink>
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<t:zone t:id="timeArea" id="timeArea">
    The current time is ${currentTime}
</t:zone>

The corresponding Java code looks like this:

@Inject
private AjaxResponseRenderer ajaxResponseRenderer;

@InjectComponent
private Zone timeArea;

@Property
private Date currentTime;
 ...
void onUpdateTime()
{
    currentTime = new Date();
   ajaxResponseRenderer ajaxResponseRenderer.addRender(timeArea);
} 

That onUpdateTime method is just an ordinary Tapestry event handler, except that it uses an injected AjaxResponseRenderer to tell Tapestry what zone to update when the link is clicked.

ZonesZones

Zones are Tapestry's approach to performing partial page updates. A Zone component renders as an HTML element, typically a <div>.

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A Zone can be updated via an EventLink, ActionLink or Select component, or by a Form. All of these components support a zone parameter, which provides the id of the Zone's <div>the async and/or zone parameters. Clicking such a link will invoke an event handler method on the server as normal ... except that the return value of the event handler method is used to send a partial page response to a partial page response is sent to the client, and the content of that response is used to update the Zone's <div> in place.

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Event Handler Return Types

{float:right|background=#eee|padding=0 1em}
    *JumpStart Demo:*

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Event Handler Return Types

{float:right|background=#eee|padding=0 1em}
    *JumpStart Demo:*
    [AJAX ActionLink|http://jumpstart[AJAX ActionLink|http://jumpstart.doublenegative.com.au/jumpstart/examples/ajax/actionlink]
{float}

In contrast, with a Zone update, the return value is may used to render a partial response within the same request.

This return value is often just the zone's own body (as below), but it can also be an injected component or block. The value will be rendered, and that markup will be used on the client side to update the Zone's <div>.

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