Compare SSE and WebSockets

Incident updates naturally flow from server to many browsers, while a shared drawing surface sends frequent messages in both directions. That contrast gives us something useful to test instead of a rule to memorize.

SSE is an HTTP response that carries server-to-browser events; WebSockets create a full-duplex message channel after an HTTP upgrade. The useful target is not encyclopedic coverage. Make one deliberate choice, observe its consequences, and know which requirement would make you revise it.

The happy path can hide a bad design: you can choose by popularity instead of message direction, deployment support, and reconnection behavior and still get one successful demo. Push past the demo. draw the actual message arrows and select SSE or WebSockets from those arrows and the operating constraints, then test the condition most likely to prove the choice wrong.

The module is moving toward one outcome: Choose the least complicated channel that meets the product requirement, and keep a non-live path for recovery. Save the before-and-after evidence now; it will make the final project review much more honest.

Sketch both architectures for the status board, including authentication, proxies, reconnects, and a snapshot request. Save the evidence, then explain which requirement would force you to choose a different design.