EXCHANGE UNIVERSE · UNDER THE SURFACE
Where do the rates on your chart come from?
You choose currencies. The app reuses saved observations or asks its rate source for missing data. This small machine explains the difference.
Animated example—not live API activity. No requests are sent.
What you are watching The drawer holds saved rates. The press represents a request to APILayer. The tray holds waiting requests, and the gate prevents another request while the app must wait.
Fig 1From observations to your chartTap a part to exploreSaved data example
What the technical words mean
- Saved rates / cache
- Observations stored so the app can reuse them instead of asking again.
- Rate source / provider
- APILayer, the external service supplying exchange-rate observations.
- Request / job
- One task to obtain current rates, currency names or a range of daily history—not a visitor or a currency trade.
- Waiting requests / queue
- Data tasks waiting behind the one currently running.
- Cooldown
- A required pause before the app may try another request.
- Fetch time vs observation time
- When the app received data can differ from when the provider observed the rates.
Waiting for this server…
No snapshot received.
- Saved data received
- Unknown
- Data being requested now
- Unknown
- Requests waiting
- Unknown
- Daily-history requests
- Unknown
- Can Refresh rates request new data?
- Unknown
- Automatic check interval
- Unknown
No provider observation timestamp received.
This example does not fetch rates or change the live app. The code references in the case study explain the implementation.