From: John Roesler <j...@confluent.io> > As you noticed, a windowed computation won't work here, because you would > be wanting to alert on things that are absent from the window.
> Instead, you can use a custom Processor with a Key/Value store and schedule > punctuations to send the alerts. For example, you can store the state and > the time of the transition to that state, and finally whether an alert has > been sent for that widget. You can schedule a punctuation to scan over the > whole store. For any record that's been disconnected for more than 5m and > *not* sent an alert, you send the alert and set the "sent" flag. Since you > only need to consider widgets whose last transition was a disconnect and > that have *not* had an alert sent, you can keep the store pretty compact by > dropping entries when you send the alert or when they transition from > "disconnected to connected". So the store doesn't need to contain any > widget whose state is currently "connected" or who is disconnected and has > already been alerted. Ta, I'll give something like that a try (the other scenario is simpler so I'll do the harder one first). One question: how does resilience work? If for example the application crashes after receiving a "disconnected" message but before timing it out? Does the preservation of the local data store across application restarts just sort all this out for me automagically so I don't have to worry about it? (I'll be deploying to Kubernetes, and applications going away and restarting at random seems to be a fact of life there.) Tim Ward The contents of this email and any attachment are confidential to the intended recipient(s). If you are not an intended recipient: (i) do not use, disclose, distribute, copy or publish this email or its contents; (ii) please contact the sender immediately; and (iii) delete this email. Our privacy policy is available here: https://origamienergy.com/privacy-policy/. Origami Energy Limited (company number 8619644); Origami Storage Limited (company number 10436515) and OSSPV001 Limited (company number 10933403), each registered in England and each with a registered office at: Ashcombe Court, Woolsack Way, Godalming, GU7 1LQ.
