The message store is a Postgres database that stores the streams, events, and commands that are the fundamental building blocks of evented and autonomous services.

The message store provides functions for writing messages to streams, and reading messages from entity streams and category streams. Messages are stored in a single table.

The Eventide toolkit's message store library provides a Ruby interface to the message store database, and the messaging library provides a message-oriented interface with support for message transformation to and from JSON, message handling, and affordances for metadata and more advanced messaging patterns.