April 2020
Intermediate to advanced
292 pages
6h 50m
English
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Accepting Potential Duplication
If you had an uneasy feeling as you went through how we handled idempotence here, that’s awesome that you’re developing a sense for it. Before publishing the video, we checked to see if the video was already done. We only have a single video-publishing instance, so we don’t have to worry about two or more instances competing with one another. However, we could very well transcode the video and get restarted due to deployment or crash before writing the VideoPublished event. When it restarts, it’ll see the PublishVideo command and do it all over again.
Transcoding videos is cheap, and we absolutely cannot accept failing to transcode the videos—they don’t go out to our viewers if they don’t get transcoded. Also, ...