I don't think on the server side env you can use window.eventSource.

Thanks for the info. I haven't heard about api-umbrella. Just visit the site and the documentation and I think I like what I see, small, easy to read and straight to the point. I will try to play with that some days.

I think that's a correct strategy of IBM. In the area of cloud native java applications, IBM seems to fall far behind other competitors regarding application servers and framework. So to be competent again, they need to find expert in the field with established technology and framework... Red hat fills in their needs really well. If I have nothing but money, I will also do the same. This is survey for your reference. Things should make more sense. https://arjan-tijms.omnifaces.org/2018/05/java-ee-survey-2018-results.html