The ajax a template is used to make asynchronous calls to the server when the user clicks on the a href link. It is useful when you need to communicate information back to the application from the UI, without requiring the entire page to be re-rendered. An example would be removing an item from a list.

The preInvokeJS attribute is used to determine whether the URL specified should be called or not, and must contain Javascript that returns true or false. If you want to call a JavaScript function, use the format preInvokeJS='yourMethodName(data,type)'. An example would be to show a confirm dialog to the user to double check whether they want to remove a user from a list.

Remember: the content returned by the href attribute must be JavaScript. That JavaScript will then be evaluated within the webpage. If you only wish to publish an event to the topic specified, then simply return no result (or NONE) from your action and utilize the notifyTopics attribute to specific the topic names.

For an example of the interaction between the div tag and the a tag using the topic pub/sub model, see the examples in the ajax div template.