From time to time web developers may find that they need to leverage more than one Ajax framework in a single web site. Perhaps they are working on mashups or portals, or maybe they simply cannot do everything they need with a single framework. Whatever the reason, OpenAjax Hub is the solution to their problem.
OpenAjax Hub is a project being managed by the OpenAjax Alliance, a group dedicated to "the adoption of open and interoperable Ajax-based web technologies". Most of this is done via the "Event Hub".
Compliant frameworks must be able to publish and subscribe to events. These events are translated from the publishing framework's event model to that of the hub and finally to that of the subscribing framework. The event hub itself is under 3KB of JavaScript and the adapters for each framework are expected to be quite small.
In March 2007 the OpenAjax Alliance held their first InteropFest wherein twelve vendors integrated a preliminary version into their frameworks. Based on that work, they are nearing completion of the first release version and accompanying specifications.
Though a member of the alliance, Microsoft was not among the twelve initial companies. However Bertrand Le Roy has recently submitted an entry on behalf of Microsoft and it's ASP.NET AJAX framework.
Future plans for OpenAjax Hub include a standard for drag and drop operations and data binding across frameworks.