> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fusioncat.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Concepts

> Definitions of the key components and entities used in Fusioncat

This glossary defines the key terms you’ll encounter when working with Fusioncat.
Use it as a quick reference to understand how schemas, messages, servers,
resources, applications, projects, and workspaces fit together in logical order
from the smallest building blocks to the containers that encapsulate them.

# Overview

Overview
Below is the list of glossary entries in the order they build on each other:

* Data schema
* Message
* Server
* Resources
* Application
* Consumer
* Producer
* Project
* Workspaces

# Glossary

## Data schema

A formal definition of the structure and data types within a payload.
Fusioncat is designed to support three schema technologies—JSONSchema,
Avro, and Protobuf—but currently only **JSONSchemas** are implemented.

**Versioning**.<br />
Every change to a schema yields a new version, numbered sequentially starting at 1.

## Message

A communication asset that carries data according to a particular schema version. Each message includes:

* A name and human-readable description.
* A reference to a specific schema and its version.
* Its own version number for tracking changes to the message metadata or payload structure.

**Note**: One schema can be used by multiple messages.

## Server

Software or infrastructure that routes messages between producers and consumers. Examples include:

* Kafka brokers
* AMQP (RabbitMQ) servers
* MQTT brokers
* Simple setups using database tables or webhooks
* A server can host multiple resources.

## Resources

Access points through which messages flow inside a server. Depending on server type, a resource might be one of:

* Kafka topic
* AMQP exchange or queue
* MQTT topic
* Database table
* Webhook endpoint

Each resource:

* Belongs to exactly one server.
* Has one of four modes: `read`, `write`, `readwrite`, or `bind`.
* The bind mode (AMQP-specific) links exchanges to queues.
* Uses a naming convention that fully qualifies its server, mode, and identifier,
  for example: `async+amqp://mainrmq@read/queue/paymentqueue`

## Application

A computer program built on the Fusioncat stack that receives and/or sends messages.

* Consumer
  * The component responsible for receiving incoming messages.
  * Defined by a list of message-and-resource pairs from which it reads.

* Producer
  * The component responsible for sending messages.
  * Defined by a list of message-and-resource pairs to which it writes.

## Project

A self-contained package that stores all schemas, messages, servers, resources, and applications.

* Everything in Fusioncat lives in a project.
* In future releases, projects will be able to reference artifacts in other projects.

## Workspaces

Top-level containers for organizing multiple projects and teams.

* A workspace typically includes several engineers.
* Engineers have access controls scoped to the projects within their workspace.