Login into Liferay Portal through Vaadin Portlet

Hello guys,

i need help. Can anyone tell how to connect the Login into liferay portal with our own vaadin portlet??

In vaadin, there is LoginForm().
But how to connect it to the liferay Portal?

So when a user log in from my vaadin portlet, that means this user is automatically logged in to the liferay portal.

can anyone help me?