Struct StdioClientTransport 

pub struct StdioClientTransport { /* private fields */ }

Client transport that communicates with a subprocess via stdio.

Spawns a child process and communicates using line-delimited JSON-RPC messages over stdin (write) and stdout (read). By default stderr is inherited so server debug output appears in the client’s terminal. A caller using Self::spawn_command may redirect or pipe it instead.

Implementations

impl StdioClientTransport

pub async fn spawn(program: &str, args: &[&str]) -> Result<Self>

Spawn a new subprocess and connect to it.

Errors

Returns an error if the process fails to spawn or if stdin/stdout handles cannot be acquired.

pub async fn spawn_command(cmd: &mut Command) -> Result<Self>

Spawn from a pre-configured Command.

This allows setting environment variables, working directory, and other process configuration before spawning.

Stdin and stdout are automatically set to piped. Stderr keeps the Command configuration; its default is inherited.

Example

use tokio::process::Command;
use tower_mcp::client::StdioClientTransport;

let mut cmd = Command::new("npx");
cmd.args(["-y", "@modelcontextprotocol/server-github"])
   .env("GITHUB_TOKEN", "ghp_...");
let transport = StdioClientTransport::spawn_command(&mut cmd).await?;

pub fn take_stderr(&mut self) -> Option<ChildStderr>

Take the child’s piped stderr handle, if the command configured one.

This returns None when stderr is inherited, redirected elsewhere, or has already been taken. It is useful for clients that need to integrate server diagnostics with their own terminal or logging UI.

pub fn from_child(child: Child) -> Result<Self>

Create from an existing child process.

The child must have piped stdin and stdout.

Trait Implementations

impl ClientTransport for StdioClientTransport

fn send<'life0, 'life1, 'async_trait>( &'life0 mut self, message: &'life1 str, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Send a raw JSON message to the server.

fn recv<'life0, 'async_trait>( &'life0 mut self, ) -> Pin<Box<dyn Future<Output = Result<Option<String>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Receive the next raw JSON message from the server.

fn is_connected(&self) -> bool

Check if the transport is still connected.

fn close<'life0, 'async_trait>( &'life0 mut self, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Close the transport gracefully.

fn reset_session<'life0, 'async_trait>( &'life0 mut self, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Reset the transport’s session state for re-initialization.

fn cancel_request<'life0, 'life1, 'async_trait>( &'life0 mut self, request_id: &'life1 RequestId, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Cancel one in-flight request.

fn supports_session_recovery(&self) -> bool

Whether this transport supports automatic session recovery.