Struct ClientStdioTransport

pub struct ClientStdioTransport { /* private fields */ }

Client transport that communicates with an MCP server over standard I/O.

The ClientStdioTransport launches a child process specified by the provided program and arguments, then communicates with it using the standard input and output streams. It implements the Transport trait to send requests and receive responses over these streams.

This transport is useful for:

• Running local MCP servers as child processes
• Command-line tools that need to communicate with MCP servers
• Testing and development scenarios

Example

use mcp_core::transport::{ClientStdioTransport, Transport};
use anyhow::Result;

async fn example() -> Result<()> {
    let transport = ClientStdioTransport::new("my-mcp-server", &["--flag"])?;
    transport.open().await?;
    // Use transport...
    transport.close().await?;
    Ok(())
}

Implementations

impl ClientStdioTransport

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

Creates a new ClientStdioTransport instance.

Arguments

• program - The path or name of the program to execute
• args - Command-line arguments to pass to the program

Returns

A Result containing the new transport instance if successful

Trait Implementations

impl Clone for ClientStdioTransport

fn clone(&self) -> ClientStdioTransport

Returns a duplicate of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Transport for ClientStdioTransport

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

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

Opens the transport by launching the child process and setting up the communication channels.

This method:

1. Spawns the child process with the configured program and arguments
2. Sets up pipes for stdin and stdout
3. Starts a background task for handling incoming messages

Returns

A Result indicating success or failure

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

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

Closes the transport by terminating the child process and cleaning up resources.

This method:

1. Kills the child process
2. Clears the stdin and stdout handles

Returns

A Result indicating success or failure

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

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

Polls for incoming messages from the child process’s stdout.

This method reads a line from the child process’s stdout and parses it as a JSON-RPC message.

Returns

A Result containing an Option<Message>. None indicates EOF.

fn request( &self, method: &str, params: Option<Value>, options: RequestOptions, ) -> Pin<Box<dyn Future<Output = Result<JsonRpcResponse>> + Send + Sync>>

Sends a request to the child process and waits for a response.

This method:

1. Creates a new request ID
2. Constructs a JSON-RPC request
3. Sends it to the child process’s stdin
4. Waits for a response with the same ID

Arguments

• method - The method name for the request
• params - Optional parameters for the request
• options - Request options (like timeout)

Returns

A Future that resolves to a Result containing the response

fn send_response<'life0, 'async_trait>( &'life0 self, id: RequestId, result: Option<Value>, error: Option<JsonRpcError>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

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

Sends a response to a request previously received from the child process.

Arguments

• id - The ID of the request being responded to
• result - Optional successful result
• error - Optional error information

Returns

A Result indicating success or failure

fn send_notification<'life0, 'life1, 'async_trait>( &'life0 self, method: &'life1 str, params: Option<Value>, ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + 'async_trait>>

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

Sends a notification to the child process.

Unlike requests, notifications do not expect a response.

Arguments

• method - The method name for the notification
• params - Optional parameters for the notification

Returns

A Result indicating success or failure