Channels Overview

This page covers Rust-specific channel details. For the general concept of what a channel is, see Channels.

Built-in channels

InMemoryChannel Same-process registry-to-registry transport via Arc-shared message queues.

MCPChannel Expose a registry's public commands as MCP tools for AI agents.

Note

HTTP and MessagePort transports are not yet shipped on the Rust side. For HTTP-reachable registries today, consume a TypeScript HTTP server from Rust by implementing a thin CommandChannel around the wire protocol (it’s byte-identical to the TS one).

The CommandChannel trait

All channels implement the CommandChannel trait:

pub trait CommandChannel: Send + Sync {
    fn id(&self) -> &str;
    fn start(&self) -> BoxFuture<'_, Result<(), ChannelError>>;
    fn close(&self) -> BoxFuture<'_, ()>;
    fn send(&self, msg: Message) -> Result<(), ChannelError>;
    fn recv(&self) -> BoxFuture<'_, Option<Message>>;
}

Method	Description
id()	Unique identifier for this channel
start()	Handshake/setup, called once before first recv
close()	Tear down; subsequent send returns Err(Closed), recv returns None
send(msg)	Fire-and-forget send to the peer
recv()	Await the next inbound message, or None on close

The async methods return BoxFuture so dyn CommandChannel stays object-safe (same shape #[async_trait] would produce).

Registering channels

use std::sync::Arc;
use coralstack_cmd_ipc::prelude::*;

let channel: Arc<dyn CommandChannel> = /* ... */;
let driver = registry.register_channel(channel).await?;
tokio::spawn(driver);  // or any executor

register_channel returns a Future<Output = ()> — spawn it yourself on tokio, async-std, smol, or futures::executor::ThreadPool. The future resolves when the channel closes, and commands owned by the channel are cleaned up automatically at that point.