modelcontextprotocol_server/transport/
stdio.rs

1// mcp-server/src/transport/stdio.rs
2use anyhow::Result;
3use async_trait::async_trait;
4use mcp_protocol::messages::JsonRpcMessage;
5use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
6use tokio::sync::mpsc;
7use tracing::debug;
8
9/// Transport implementation that uses stdio to communicate with the client
10#[derive(Clone)]
11pub struct StdioTransport;
12
13impl StdioTransport {
14    /// Create a new stdio transport
15    pub fn new() -> Self {
16        Self
17    }
18}
19
20#[async_trait]
21impl super::Transport for StdioTransport {
22    async fn start(&self, message_tx: mpsc::Sender<JsonRpcMessage>) -> Result<()> {
23        let stdin = tokio::io::stdin();
24        let mut reader = BufReader::new(stdin);
25        let mut line = String::new();
26
27        tokio::spawn(async move {
28            while reader.read_line(&mut line).await.unwrap_or(0) > 0 {
29                debug!("Received line: {}", line);
30                match serde_json::from_str::<JsonRpcMessage>(&line) {
31                    Ok(message) => {
32                        if message_tx.send(message).await.is_err() {
33                            break;
34                        }
35                    }
36                    Err(err) => {
37                        tracing::error!("Failed to parse JSON-RPC message: {}", err);
38                    }
39                }
40
41                line.clear();
42            }
43        });
44
45        Ok(())
46    }
47
48    async fn send(&self, message: JsonRpcMessage) -> Result<()> {
49        let mut stdout = tokio::io::stdout();
50        let serialized = serde_json::to_string(&message)?;
51
52        debug!("Sending message: {}", serialized);
53        stdout.write_all(serialized.as_bytes()).await?;
54        stdout.write_all(b"\n").await?;
55        stdout.flush().await?;
56
57        Ok(())
58    }
59
60    async fn close(&self) -> Result<()> {
61        // No need to do anything special for stdio
62        Ok(())
63    }
64    
65    fn box_clone(&self) -> Box<dyn super::Transport> {
66        Box::new(self.clone())
67    }
68}
modelcontextprotocol_server/transport/stdio.rs

modelcontextprotocol_server/transport/
stdio.rs
