Why isn't an custom implemented VaadinServiceInitListener is listening in vaadin 13.0.2? - vaadin

Question

I would like to validate user is signed in or not to achieve it i found something called VaadinServiceInitListener in vaadin 13.0.2 This class is used to listen to BeforeEnter event of all UIs in order to check whether a user is signed in or not before allowing entering any page.
I have created an vaadin 13.0.2 project with app-layout-addon by appreciated implemented login functionality and VaadinServiceInitListener to check whether a user is signed in or not.
public class AAACATInitListener implements VaadinServiceInitListener {
private static final long serialVersionUID = 1L;
private static InAppSessionContextImpl appContextImpl;
#Override
public void serviceInit(ServiceInitEvent event) {
System.out.println("in service init event");
event.getSource().addUIInitListener(new UIInitListener() {
private static final long serialVersionUID = 1L;
#Override
public void uiInit(UIInitEvent event) {
event.getUI().addBeforeEnterListener(new BeforeEnterListener() {
private static final long serialVersionUID = 1L;
#Override
public void beforeEnter(BeforeEnterEvent event) {
appContextImpl = (InAppSessionContextImpl)VaadinSession.getCurrent().getAttribute("context");
if (appContextImpl == null) {
WebBrowser webBrowser = UI.getCurrent().getSession().getBrowser();
String address = webBrowser.getAddress();
if(RememberAuthService.isAuthenticated(address) != null && !RememberAuthService.isAuthenticated(address).isEmpty()) {
//System.out.println("Found Remembered User....");
IBLSessionContext iblSessionContext = null;
try {
iblSessionContext = new UserBLManager().doRememberedStaffUserLogin(RememberAuthService.isAuthenticated(address), "");
if(iblSessionContext != null) {
InAppSessionContextImpl localAppContextImpl = new InAppSessionContextImpl();
localAppContextImpl.setBLSessionContext(iblSessionContext);
localAppContextImpl.setModuleGroupList(iblSessionContext.getSessionAccessControl().getPermittedModuleGroups());
appContextImpl = localAppContextImpl;
event.rerouteTo(ApplicationMainView.class);
}else {
Notification.show("Your access has been expired, Please contact your administrator", 5000, Position.BOTTOM_CENTER);
}
} catch (AuthenticationFailedException e) {
Notification.show("Authentication Failed, Please Reset Cookies And Try Again", 5000, Position.BOTTOM_CENTER);
} catch (Exception e){
e.printStackTrace();
Notification.show("Unexpected Error Occurred, Please Reset Cookies And Try Again", 5000, Position.BOTTOM_CENTER);
}
}else {
System.out.println("Session context is null, creating new context");
appContextImpl = new InAppSessionContextImpl();
VaadinSession.getCurrent().setAttribute("context", appContextImpl);
event.rerouteTo(LoginView.class);
}
} else {
System.out.println("Session context is not null");
InAppSessionContextImpl localAppContextImpl = new InAppSessionContextImpl();
localAppContextImpl.setBLSessionContext(appContextImpl.getBLSessionContext());
localAppContextImpl.setModuleGroupList(appContextImpl.getModuleGroupList());
appContextImpl = localAppContextImpl;
event.rerouteTo(ApplicationMainView.class);
}
}
});
}
});
}
public static void setBLSessionContext(IBLSessionContext iblSessionContext) {
appContextImpl.setBLSessionContext(iblSessionContext);
}
public static void setModuleGroupList(List<ModuleGroupVO> moduleGroupList) {
appContextImpl.setModuleGroupList(moduleGroupList);
}
private class InAppSessionContextImpl implements InAppSessionContext {
private static final long serialVersionUID = 1L;
private List<ModuleGroupVO> moduleGroupList;
private IBLSessionContext iblSessionContext;
private Map<String, Object> attributeMap;
public InAppSessionContextImpl() {
this.attributeMap = new HashMap<String, Object>();
}
#Override
public List<ModuleGroupVO> getModuleGroupList() {
return moduleGroupList;
}
public void setModuleGroupList(List<ModuleGroupVO> moduleGroupList) {
this.moduleGroupList = moduleGroupList;
}
#Override
public IBLSessionContext getBLSessionContext() {
return iblSessionContext;
}
public void setBLSessionContext(IBLSessionContext iblSessionContext) {
this.iblSessionContext = iblSessionContext;
}
#Override
public IBLSession getBLSession() {
if(iblSessionContext != null)
return iblSessionContext.getBLSession();
return null;
}
#Override
public boolean isPermittedAction(String actionAlias) {
if (getBLSessionContext() != null) {
if (getBLSessionContext().getSessionAccessControl() != null) {
return getBLSessionContext().getSessionAccessControl().isPermittedAction(actionAlias);
}
}
return false;
}
#Override
public void setAttribute(String key, Object attribute) {
attributeMap.put(key, attribute);
}
#Override
public Object getAttribute(String key) {
return attributeMap.get(key);
}
}
}
Expected results redirect to login page if user not signed in or else to main application page but AAACATInitListener is not listening.

Answer 1

If you are using Spring, simply add a #Component annotation to the class and it should work. If youre not using Spring, follow #codinghaus' answer.

Answer 2

To make Vaadin recognize the VaadinServiceInitListener you have to create a file called com.vaadin.flow.server.VaadinServiceInitListener and put it under src/main/resources/META-INF/services. Its content should be the full path to the class that implements the VaadinServiceInitListener interface. Did you do that?
You can also find a description on that in the tutorial.

Answer 3

The correct pattern to use beforeEnter(..) is not do it via VaadinServiceInitListener , instead you should implement BeforeEnterObserver interface in the view where you need use it and override beforeEnter(..) method with your implementation.
public class MainView extends VerticalLayout implements RouterLayout, BeforeEnterObserver {
...
#Override
public void beforeEnter(BeforeEnterEvent event) {
...
}
}