What is the client-side behavior of a JSF WebSocket when it is removed from the DOM

Question

I have several panels, each displaying some contents, and zero, one, or more of these panels can be displayed, as in the following example:

<div jsf:id="contents">
    <ui:fragment rendered="#{aContent.rendered}">
        <h:form>
            <o:socket channel="a-channel" onmessage"onAMessage"/>
            <o:commandScript name="onAMessage"
                             actionListener=#{aContent.update()}"
                             render=":aComponent"/>
        </h:form>
        <my:aComponent id="aComponent" />
    </ui:fragment>

    <ui:fragment rendered="#{bContent.rendered}">
        <h:form>
            <o:socket channel="b-channel" onmessage"onBMessage"/>
            <o:commandScript name="onBMessage"
                             actionListener=#{bContent.update()}"
                             render=":bComponent"/>
        </h:form>
        <my:bComponent id="bComponent" />
    </ui:fragment>
</div>

I would like to know what happens to the client side web socket when one of these UI fragments is removed from the DOM after an AJAX update of the enclosing element.

Is the web socket closed? Should I consider another approach?

Answer 1

Based on how it's currently implemented, it'll keep running. You need to repeat the condition in the connected attribute.

<ui:fragment rendered="#{aContent.rendered}">
     <o:socket ... connected="#{aContent.rendered}" />

Perhaps this will be improved later when I plan to add <f:ajax> support for <o:socket>.

On the other hand, your code snippet is non-DRY. Try restricting to only 1 socket+commandScript combination which does its job dynamically based on contents of the pushed message. See also Channel design hints section of the documentation.