Terminology

The wiki uses the ecosystem's own vocabulary so that upstream documentation reads correctly against Relay. Where Relay needs a word the ecosystem does not have, it is defined here rather than invented per page.

Ecosystem terms

Executor. One running process of an application that uses the workflow library. It opens an outbound WebSocket to the control plane, and it owns its system database, which Relay accesses only via official SDK client methods when an opt-in data plane is configured, never via direct raw SQL. It carries an identifier, an application name, and an application version. How the identifier is generated and when it changes are open questions until the protocol specification closes them.

Application. A named unit that executors belong to. Names are constrained by the published API specification, and Relay copies those constraints exactly.

Organisation. The tenancy boundary above applications, as modelled by the published API.

System database. The application's own Postgres database, holding workflow and step state. Off limits to direct raw SQL from Relay; accessed only via the official SDK client when an opt-in data plane is configured.

Workflow, step, queue, schedule. The library's own concepts. Relay never redefines them; it lists, reads, and manipulates them through executors.

Recovery. Asking a healthy executor to take over the pending workflows of an executor that has been declared dead. The public documentation describes the library's execution guarantees as at-least-once for steps and exactly-once for outcomes, which is what makes a repeated recovery request cheap. Relay's design leans on that, and the claim is still to be confirmed against the SDK source.

Relay terms

Instance. One running Relay process. Several instances share one Relay database.

Ownership. The relationship between an instance and an executor connection. Exactly one instance owns a given connection and holds a lease on it in the database. A request arriving at a non-owning instance is forwarded to the owner.

Hub. The component that accepts executor connections and correlates requests with responses over them.

Router. The component that picks a healthy executor for a request, and forwards to a peer instance when the connection is owned elsewhere.

Words this project does not use for itself

Relay does not use the ecosystem's trademarks in its own name, package names, module names, binary name, logo, or domain. Module names are covered because a module name ends up as a package name. Descriptive prose such as "compatible with the Conductor protocol" is fine, and is how the compatibility target is named throughout this wiki.

For the same reason Relay's own dashboard is called the dashboard, never the console. Console is the vendor's product name and appears in this wiki only when referring to that product.