The developer then includes code so that each chart widget and data grid widget subscribes to the new date event and provides a callback function. The various callback functions then update the given visualization widget appropriately:

<script type="text/javascript">
    ...
    function SubscribeNewDateCallback(eventname, publisherData, subscriberData) {
    ...
    // Update the given visualization widget
    ...
    }
    // Subscribe to (i.e., listen for) any
    // "myapp.newdata" events via the OpenAjax Hub
    OpenAjax.hub.subscribe("myapp.newdate", SubscribeNewDateCallback);
    ...
</script>

InteropFest 1.0 - Examples of the Hub in Action
The InteropFest 1.0 was an interoperability event spanning the months of July to September 2007 in which multiple AJAX products and toolkits used the OpenAjax Hub 1.0 to achieve multi-toolkit integration. You can find several examples of OpenAjax Hub 1.0 in action on the wiki page for the InteropFest: www.openajax.org/member/wiki/InteropFest_1.0.

OpenAjax Hub 1.1 and Beyond
The members of OpenAjax Alliance have already begun work toward OpenAjax Hub 1.1, which is likely to extend the pub/sub manager outside of a single browser frame and address the following scenarios:
•  Mediating multiple Comet connections: The Communications Hub Task Force at OpenAjax Alliance is addressing technical issues around Comet (AJAX server-push), particularly how to allow Comet to work in mashup scenarios in today's browsers where the mashup might have multiple push components (and thus exceed the browser's two connection limit).
•  Cross-frame messaging: Cross-frame messaging is likely to be a requirement in certain mashup scenarios.
•  Secure Mashups: The Security Task Force at OpenAjax Alliance is addressing the secure mashup question. The objective is to allow multiple arbitrary components to be used within a mashup, but where each component is isolated (sandboxed) from the other components and where the components communicate with each other over a secure message bus.

Down the road, OpenAjax Hub might add APIs for local persistent storage and offline support, a collection of standard messages and payloads, copy/paste and drag/drop support, and features to support data binding across AJAX libraries.

Today, OpenAjax Hub 1.0 provides key integration services that enable multiple AJAX toolkits to co-exist and talk to each other within the same Web page. Going forward, OpenAjax Hub 1.1 will expand into areas critical to Web 2.0 applications such as Comet-style communications, cross-frame messaging, and secure mashups.

Links to the Specifications and Open Source
Detailed information about the Hub can be found at the following locations:
•  The OpenAjax Hub 1.0 specification:
www.openajax.org/member/wiki/OpenAjax_Hub_Specification
•  Open source reference implementation:
http://openajaxallianc.sourceforge.net
•  InteropFest 1.0:
www.openajax.org/member/wiki/InteropFest_1.0