Viewing Simulated Messages
Every request received by a simulated server is logged in the message history. You can inspect what was sent, which response was returned, and debug matching issues.
What it does
The Message History view lists all captured messages and lets you open any one to see the full request and response. It also shows direction (incoming/outgoing), whether the message was secured, and whether it was authenticated.
When to use
- Debug why a particular response (or default) was returned instead of the expected one.
- Confirm a simulated endpoint actually received a request and inspect its body/headers.
- Compare a simulated-server request against requests you sent manually.
How to use
Accessing simulation messages
Two ways to view simulated messages:
- From the Service Simulation view — select Message History from the server selector strip at the top. The history browser opens inline (its header is hidden in this mode).
- From the left navigation — click Message History to open the full view with its own header and a Refresh button.
Understanding the list
Each message row shows icons for:
- Outgoing (↑) — a request you sent in API Playground.
- Incoming (↓) — a request received by a simulated server.
- Secured / Unsecured — whether the transport was secured.
- Authenticated — whether the request carried authentication.
The title summarizes the message, and the date appears on hover.
Inspecting a message
Click any message to open the details panel, which has Request, Response, and Error tabs. You can see:
- Request: full URL, HTTP method, headers, and body.
- Response: status code, headers, body, and the matched response (including the condition that triggered it, or "Default" when none matched).
- Error: any error captured for the message.
Timing is shown as Prep:, TTFB:, Receive:, and Total:.
Live diagnostics in the Service Simulation view
The Diagnostics panel at the bottom of the Service Simulation view shows a live text log of incoming requests for the selected server (matched handler, response, status, and elapsed time). Use the chevron toggle to collapse or expand it. The same live feed is also printed in a structured Timestamp | Service | Uri | Response | Status | Delay format when you run a server from the CLI — see Starting & Stopping Servers.
Empty state
When no messages exist, the view shows: "Nothing here yet — Send some requests or activate service simulation to see messages appear in the history." Use Refresh to reload the list after activity.
Clearing simulation history
Simulation request counts (the Requests column) reset when a server is restarted. The message history itself follows the global history retention setting in Settings → General → Max Historized Messages.