[ https://issues.jboss.org/browse/CDI-729?page=com.atlassian.jira.plugin.sy... ] Romain Manni-Bucau commented on CDI-729: ---------------------------------------- I'm using events because I don't know the impl I will use (it is a library which is integrated with some 3rd party backend). The event is very handy on both side since it doesn't couple strongly both maintainers. The only blocking point is to have what CDI provides in synchronous mode: return when done. For completionstage it is providing a way to register another stage in the event chain. I can't put the chaining in the caller (because I don't know it) I can't throw an exception in the observer because the processing is done through a completionstage in another thread so it is missed and likely happen after the caller already returned anyway (timing issue). This is also why fire() (not async) doesn't work. I'm not sure I got your solution but sounds like registering a task to delay the completion of the returned stage is not a big deal (clearly not in impl side) and would help to be reactive in apps. -- This message was sent by Atlassian JIRA (v7.5.0#75005)