Channels

Channels are the transport layer in cmd-ipc. They abstract the underlying communication mechanism so the same command API works over Web Workers, HTTP, MCP, in-memory pipes, or anything you implement yourself.

What is a channel?

A channel is a bidirectional communication pipe that:

• Has a unique ID used by the registry as a routing key
• Sends and receives messages (the protocol’s seven Message variants — see Protocol)
• Signals connection close so the registry can clean up
• Can operate in client or server mode, depending on the channel type

Each language implementation defines its own channel interface (ICommandChannel in TypeScript, CommandChannel trait in Rust) and ships a set of built-in channel implementations. The wire format is byte-identical across languages, so a TypeScript peer and a Rust peer can exchange messages over any transport both support.

Channel lifecycle

1. You construct a channel and pass it to registry.registerChannel(channel) (TS) or registry.register_channel(channel) (Rust).
2. The registry calls the channel’s start() to perform any handshake.
3. For client-mode channels, the registry probes the peer for its commands and caches them as “remote” for routing.
4. The registry pumps messages in both directions — your handlers run locally, remote calls route over the channel.
5. When the channel closes (peer disconnect, explicit close(), transport error), the registry drops any commands owned by that channel and stops routing to it.

Tip

Custom channels follow the same interface. Build a WebSocket channel, a gRPC channel, an AMQP channel, or whatever your application needs — the registry doesn’t care about the transport, only about the Messages flowing through it.

Language-specific interfaces and built-in channels

The channel interface shape and the available built-ins differ between the two implementations. Pick your language:

TypeScript channels ICommandChannel interface; MessagePortChannel, HTTPChannel, and MCPChannel built-ins.

Rust channels CommandChannel trait; InMemoryChannel and MCPChannel built-ins.