Implementation:ArroyoSystems Arroyo Stdout Connector

Knowledge Sources	ArroyoSystems_Arroyo
Domains	Streaming, Connectors
Last Updated	2026-02-08 08:00 GMT

Overview

StdoutConnector is a simple sink-only connector that writes serialized pipeline output to the process's standard output stream, useful for debugging and local development.

Description

The StdOut connector serializes records using a configurable format (defaults to JsonFormat if no format is specified) and writes them to tokio::io::stdout() via a BufWriter for buffered output. It uses ArrowSerializer for format conversion. The connector requires a schema and format definition, with EmptyConfig for both profile and table types. The make_operator method constructs a StdoutSink operator wrapping a buffered async stdout writer and the serializer. The connector supports custom schemas and is visible in the connector UI (hidden: false).

Usage

Use StdoutConnector for debugging Arroyo pipelines during local development, or when the output needs to be piped to another process via standard output.

Code Reference

Source Location

• Repository: ArroyoSystems_Arroyo
• File: crates/arroyo-connectors/src/stdout/mod.rs

Signature

pub struct StdoutConnector {}

impl Connector for StdoutConnector {
    type ProfileT = EmptyConfig;
    type TableT = EmptyConfig;

    fn name(&self) -> &'static str; // returns "stdout"
    fn table_type(&self, _: EmptyConfig, _: EmptyConfig) -> ConnectionType; // always Sink
    fn from_config(&self, id: Option<i64>, name: &str, config: EmptyConfig,
        table: EmptyConfig, schema: Option<&ConnectionSchema>) -> anyhow::Result<Connection>;
    fn make_operator(&self, _: EmptyConfig, _: EmptyConfig,
        c: OperatorConfig) -> anyhow::Result<ConstructedOperator>;
}

Import

use arroyo_connectors::stdout::StdoutConnector;

I/O Contract

Inputs

Name	Type	Required	Description
schema	ConnectionSchema	Yes	Schema for the data to output
format	Format	No	Serialization format (defaults to JSON if not specified)

Outputs

Name	Type	Description
stdout	Text stream	Serialized records written to standard output via buffered writer

Usage Examples

CREATE TABLE stdout_sink (
    value TEXT
) WITH (
    connector = 'stdout',
    format = 'json'
);

Related Pages

• Environment:ArroyoSystems_Arroyo_Rust_Runtime