Let’s think it through · Start with a story
A girl taps Send. Before the robot receives her message, the data may travel through a chat service.
Break down the process
- SenderSubmits a message
- ServiceReceives and routes it
- RecipientGets the message
- StatusShown according to the app
Chat systems often use servers to forward, store, or synchronize messages.
If the other person is offline, a service may hold a message and deliver it later. “Sent,” “delivered,” and “read” are different states, depending on how the app works.
Some systems also use end-to-end encryption, so the service relaying a message cannot directly read its contents.
Your turn
If a message says it was sent successfully, does that prove the recipient has seen it?
Have an answer? Click to see the explanation
Not necessarily. The service may only have accepted it; delivery to a device and actually reading it are separate things.
Takeaway
Chat systems often use servers to forward, store, or synchronize messages.
Try covering the diagram and explaining each step to someone at home. If a step is hard to explain, go back and look at that card again.