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Concepts

Concepts​

Message​

A "message" is a single timestamped log entry, which can be sent to the Foxglove app or written to an MCAP file.

Schemas​

A "schema" describes the structure of a message's contents.

Foxglove defines several schemas with visualization support. You may also define your own schemas using one of many supported encodings.

Channels​

A "channel" gives a way to log related messages which have the same schema. Each channel is identified by a unique topic name.

For Foxglove schemas, the SDK provides type-safe channels for logging messages with a known, matching schema. (Not yet supported in C++.)

You may log your own custom data by defining channels with your schemas and logging messages to them. See the quickstart example.

Sinks​

A "sink" is a destination for logged messages. A WebSocket client is a sink, as is an MCAP writer. If you do not configure a sink, log messages will simply be dropped without being recorded. You can configure multiple sinks, and you can create or destroy them dynamically at runtime.

See the quickstart example for basic usage.

MCAP​

MCAP is a container file format for multimodal log data, supported by Foxglove.