Skip to main content

Dummy Source and Stdout Sink

These two plugins are maintained in the Tenon source tree and are useful for local development:

  • org.apache.bifromq.tenon.dummy-source@0.1.0 is a Source that emits no records.
  • org.apache.bifromq.tenon.stdout-sink@0.1.0 prints Sink messages to live diagnostics.

Build the Runner, cargo-tenon, and both plugins from the same source checkout. The commands create local plugin archives; no prebuilt Tenon artifact is needed:

cargo install --path sdk/rust/cargo-tenon --locked
cargo tenon bundle --locked \
  --manifest-path plugin/bifromq-tenon-dummy-source-plugin/Cargo.toml > dummy-bundle.json
cargo tenon bundle --locked \
  --manifest-path plugin/bifromq-tenon-stdout-sink-plugin/Cargo.toml > stdout-bundle.json

Install the bundle paths reported in those JSON files through POST /plugins, then use the first pipeline to drive the Stdout Sink with a Lua timer. Both plugins accept {} as their configuration.

Use Stdout Sink with a custom Source​

Replace the idle Instance in the first pipeline with your Source's exact Program identity and configuration. Keep console as the Sink and subscribe to target=plugin%3Aconsole before sending external input. For a Source payload with string message = 1:

local output = registry:getBuilder("org.apache.bifromq.tenon.stdout-sink@0.1.0")
function main(event)
  if event.type == "source" then
    output:setMessage("received: " .. event.payload.message)
    emit(output:build())
  end
end

Change the field access and Builder identity to match your contracts. : is required for Builder calls. A process running only proves that the plugin stayed alive; the diagnostic line proves the Sink wrote an observable result.

Use Dummy Source with a custom Sink​

Bind Dummy Source as flows.probe.source, install your custom Sink, and replace the Stdout Sink Instance and Builder identity. Keep the one-shot timer pattern from the first pipeline. This is a useful local test for a Sink's configuration, payload decoding, output, and shutdown without an external Source system.

The Dummy Source never emits an empty Source record. Timer-generated records have no upstream event to replay after a crash. Timers and Lua state are per channel and are recreated when the VM or Pipeline is restarted.

See Plugin Package Format for the manifest and descriptor contract, and Awesome Tenon Plugins for other source repositories.