- Flannel: An Application-Level Edge Cache to Make Slack Scale: Slack has to send a lot of data to bootstrap clients - desktop, mobile, etc - when they first connect to servers. It adds a lot of load to the backend at a point in time when slack doesn’t know what data a user is interested in. Flannel is a cache service between the backend and clients that takes some of the load away from the backend. Teams connect to the same flannel node to improve cache relevance by consistent hashing. Much less data is sent initially and lazily loaded as needed from a near by cache. Teams connect to the closest flannel instance by geography. Also mentioned was the problem of many users disconnecting at once and reconnecting. (eg Office internet goes down …)
