Call from JavaScript to server-side code in JSF

Question

Hi, I'm looking for an easy way to call a bean's method that will take no parameters and return a string in JSF. The thing that I don't really need is that the method returns an action result and then uses the whole JSF life-cycle to do get me to another view. I need to do that from JavaScript so that I can put together some client-side parts of the application and going over the A4J part of RichFaces has brought me nothing so far.

So here's the scenario again in a step-by-step form:

1. from JS issue a GET on some address
2. on the server process that GET and return JSON or HTML (basically a string)
3. once the request is sent back to the client I want to be able to process it further with JS.

Thanks!

Answer 1

Use a4j:jsFunction and the data attribute.

So roughly you want something like:

<button onclick="callBackend();">Go</button>

<a4j:jsFunction name="callBackend" action="#{myBean.someMethod}" data="#{myBean.someString}" oncomplete="handleResponse(data);"/>

<script>
function handleResponse(response) {
   alert(response);
}
</script>

Answer 2

Damo: can you explain why it might only work for the first time the method callBackend is executed? I'm experiencing a strange behavior that the first call succeeds and the next calls are just blocked. I see the server-side code being executed but some strange result is being sent back to the browser (something like the _viewstate and those kind of things).