Can Vaadin porlets enable PortletHub support automatically?

[ujoni]

Find out, if it is possible to enable Portlet Hub for the Vaadin portlets automatically, so that the developer can leverage the Vaadin wrappers for the hub without a care in the world.

Links, where the portlet hub is activated:

• pluto-portal-driver-config.xml
• ImageSelPortlet.java
• PageResources.java

[pleku]

Pluto has a page for Portlet 3.0 features which can be used for testing the hub.
This should provide the understanding on:

• whether we can automate loading of the hub for the users
• if we should automate it always
• or if we just use the standard portlet spec for enabling this, and should document that for the users

If we need to require the users to enable the hub when they want to use IPC features, we should then throw exceptions when they use it without enabling it first.

[caalador]

Automating loading of PortletHub is possible when the portlet.xml is in portlet 3 mode
e.g. header should be:

<portlet-app xmlns="http://xmlns.jcp.org/xml/ns/portlet"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/portlet http://xmlns.jcp.org/xml/ns/portlet/portlet-app_3_0.xsd"
             version="3.0">

and then we can in VaadinPortlet have

    @Override
    public void renderHeaders(HeaderRequest request, HeaderResponse response)
            throws PortletException, IOException {
        super.renderHeaders(request, response);
        response.addDependency("PortletHub", "javax.portlet", "3.0.0");
    }

Which will then load the portletHub when we are in portlet 3.0 mode. In portlet 2.0 and 1.0 modes it will just not load anything extra.

The portlet Id is easiest to get from the response, so in the javascripts the $0 is from
VaadinPortletService.getCurrentResponse().getPortletResponse().getNamespace();

After this we can register the portlet to the hub with for instance

if (!window.Vaadin.Flow.Portlets) {
    window.Vaadin.Flow["Portlets"] = {};
}
if (!window.Vaadin.Flow.Portlets.$0) {
    if (portlet) {
        portlet.register($0).then(function (hub) {
            window.Vaadin.Flow.Portlets[$0] = hub;
            hub.addEventListener('portlet.onStateChange', function () {
                $1.server.smash(hub)
            });
        });
    }
}

The event listener for portlet.onStateChange is required else any action will result in a missing event handler warning. In the sample case it would just send the hub json to a server ClientCallable method.

and now on a button click we could use the window state chage as

var hub = window.Vaadin.Flow.Portlets.$0;
hub.setRenderState({
    'parameters': {},
    'portletMode': 'VIEW',
    'windowState': hub.windowStates[1]
});
const poller = () => {
    if (hub.isInProgress()) {
        setTimeout(poller, 10);
    } else {
        location.reload();
    }
};
poller();