Produce an Vaadin portlet API proposal from a draft

[ujoni]

During the meeting on 23.9.2019, Leif created a loose API draft based on the comments presented in the meeting.

The demonstrating code is as follows:

// Simplest possible - maybe not feasible because the portlet API is a mess
@VaadinPortletView("myPortlet")
public class MaximizedViewOrEditView extends MyComponent implements VaadinPortletView {
  @Override
  public void init(PortalComponentContext context) {
    this.addFooBarListener(event -> {
      context.sendEvent(some, parameters, here);
    });
    context.onPortletModeChange(mode -> this.setEdit(mode.equals(PortletMode.EDIT));
    context.onEvent((EventRequest request, EventResponse response) -> {
      this.setEventReceived(request.getEvent().getName));
    });
    boolean isAdmin = context.hasRole("admin");
    this.setAdminControlsAvailable(isAdmin);
  }
}
// Intermediate level with annotations
@PortletApplication(
    @EventDefinition(xyz)  
)
public class MyOtherPortlet {
  @RenderMethod("myPortlet")
  public String doThings(request) {
    if (maximised) {
      return VaadinPortlet.doThings(request, MaximizedViewOrEditView.class);
    } else {
      return "<img>";
    }
  }
  @EventMethod("someEvent")
  public void something(EventRequest req, EventResponse resp) {
    VaadinPortlet.dispatchToTheRightComponentInstance(req, resp, MaximizedViewOrEditView.class);
  }
}
// Intermediate level with xml
public class MyPortlet extends VaadinPortlet<MaximizedViewOrEditView> {
}
// Advanced case for using different components with separate @PreserveOnRefresh scopes for different render modes, but still using xml
public class MyPortlet extends VaadinPortlet {
  @Override
  protected Class<? extends Component> getRenderDefinition(PortletRequest request) {
    if (request.getPortletMode().equals(PortletMode.HELP)) {
      return HelpComponent.class;
    } else if (request.getWindowState().equals(WindowState.MAXIMIZED)) {
      return MaximizedViewOrEditView.class;
    }
  }
  doEdit(RenderRequest req, RenderRespones resp) {
    if (maximised) {
      super.doEdit(req, resp);
    } else {
      renderImg(resp);
    }
  }
}

This code should be formalized and a API draft should be produced in this repository. This API should then be used in the various demonstration projects to validate the design and find problems therein.

[pleku]

This should combine the results of the:

• Investigations: Enabling the hub Can Vaadin porlets enable PortletHub support automatically? #30 Window modes Portlet window modes #26
• Demos: Addressbook Address book demonstration version 2.0 #29 Maximixing/normalizing Demonstrate window state handling in Vaadin portlets #27

This issue can be closed when:

• The API exists either in a feature branch or PR
• There are tickets created for the next things to do to make the API happen