Design a chat service (messages, online dots and alerts)
Build the back end of a chat app from parts, press Run, and see whether it stores messages, shows who is online and sends an alert to a closed app, and whether it keeps doing so when a connection server, the cache or the alert worker dies.
Visual challengeDesign a chat service (messages, online dots and alerts)
Names
Components
Drag onto the board, or tap to add.
Traffic
Compute
Data
Messaging
Press enter or space to select a node. You can then use the arrow keys to move the node around. Press delete to remove it and escape to cancel.
Press enter or space to select an edge. You can then press delete to remove it or escape to cancel.
Settings hover or tap a component, then its iconLink drag from any dot to another componentRemove select it, press DeleteBreak Break it in a part's settings arms it; it fails when you press Run tests
Link color = the component it leaves:Entry pointsTraffic routingServersStoragedown, unlinked or overloaded
A simplified model, not a real cloud. Every request counts alike except that about 1 in 10 needs an alert (chapter 22.2), times are in model milliseconds, the cache is always warm (full of useful answers), and prices are made up to compare designs. The board counts requests a second, not open phone connections, and it cannot show message order or delivery receipts.