Hello, Thank you for the explanation as well as the link to the other post. Interesting to learn about some of the open JIRAs.
Indeed, I was not using event time, but processing time. However, even when using event time I only get notified of timeouts upon subsequent events. The link <http://pastebin.com/x4m3RHQz> contains an example where I read <key> <value> from a socket, wrap this in a custom "event" with timestamp, key the resultant stream by <key> and attempt to detect <key> instances no further than 3 seconds apart using CEP. Apart from the fact that results are only printed when I close the socket (normal?) I don't observe any change in behaviour So event-time/watermarks or not: SOME event has to occur for the timeout to be triggered. FLINK-3320 <https://issues.apache.org/jira/browse/FLINK-3320> (CEP "not" operator) does not address this because again, how would the "not match" be triggered if no event at all occurs? On Sat, Oct 8, 2016 at 12:50 AM, <lg...@yahoo.com> wrote: > The following is a better link: > > http://mail-archives.apache.org/mod_mbox/flink-user/201609.mbox/%3CCAC27z% > 3DOTtv7USYUm82bE43-DkoGfVC4UAWD6uQwwRgTsE5be8g%40mail.gmail.com%3E > > > - LF > > > > > ------------------------------ > *From:* "lg...@yahoo.com" <lg...@yahoo.com> > *To:* "user@flink.apache.org" <user@flink.apache.org> > *Sent:* Friday, October 7, 2016 3:36 PM > > *Subject:* Re: Listening to timed-out patterns in Flink CEP > > Isn't the upcoming CEP negation (absence of an event) feature solve this > issue? > > See this discussion thread: > http://mail-archives.apache.org/mod_mbox/flink-user/ > 201609.mbox/%3CCAC27z%3DOD%2BTq8twBw_1YKni5sWAU3g1S9WDpJw0DUwgiG9YX > 9Fg%40mail.gmail.com%3E > > > > // Atul > > > ------------------------------ > *From:* Till Rohrmann <trohrm...@apache.org> > *To:* user@flink.apache.org > *Sent:* Friday, October 7, 2016 12:58 AM > *Subject:* Re: Listening to timed-out patterns in Flink CEP > > Hi David, > > in case of event time, the timeout will be detected when the first > watermark exceeding the timeout value is received. Thus, it depends a > little bit how you generate watermarks (e.g. periodically, watermark per > event). > > In case of processing time, the time is only updated whenever a new > element arrives. Thus, if you have an element arriving 4 seconds after > Event A, it should detect the timeout. If the next event arrives 20 seconds > later, than you won't see the timeout until then. > > In the case of processing time, we could think about registering timeout > timers for processing time. However, I would highly recommend you to use > event time, because with processing time, Flink cannot guarantee meaningful > computations, because the events might arrive out of order. > > Cheers, > Till > > On Thu, Oct 6, 2016 at 3:08 PM, David Koch <ogd...@googlemail.com> wrote: > > Hello, > > With Flink CEP, is there a way to actively listen to pattern matches that > time out? I am under the impression that this is not possible. > > In my case I partition a stream containing user web navigation by "userId" > to look for sequences of Event A, followed by B within 4 seconds for each > user. > > I registered a PatternTimeoutFunction which assuming a non-match only > fires upon the first event after the specified timeout. For example, given > user X: Event A, 20 seconds later Event B (or any other type of event). > > I'd rather have a notification fire directly upon the 4 second interval > expiring since passive invalidation is not really applicable in my case. > > How, if at all can this be achieved with Flink CEP? > > Thanks, > > David > > > > > > >
