still you can use h:messages tag.
For example, How can I show a confirmation message after successfully persist data in database/ or a business validation message.
Java side code:
FacesContext context = FacesContext.getcurrentInstance();
context.addMessage(null, MessageUtils.getMessage(context, "Deatils saved successfully"); // we are passing component id as null here.
In UI:
<h:messages layout="table"/>
Dont specify "for" attribute here. It will show all the messages.