stdio.js•2.42 kB
import process from "node:process";
import { ReadBuffer, serializeMessage } from "../shared/stdio.js";
/**
* Server transport for stdio: this communicates with a MCP client by reading from the current process' stdin and writing to stdout.
*
* This transport is only available in Node.js environments.
*/
export class StdioServerTransport {
constructor(_stdin = process.stdin, _stdout = process.stdout) {
this._stdin = _stdin;
this._stdout = _stdout;
this._readBuffer = new ReadBuffer();
this._started = false;
// Arrow functions to bind `this` properly, while maintaining function identity.
this._ondata = (chunk) => {
this._readBuffer.append(chunk);
this.processReadBuffer();
};
this._onerror = (error) => {
var _a;
(_a = this.onerror) === null || _a === void 0 ? void 0 : _a.call(this, error);
};
}
/**
* Starts listening for messages on stdin.
*/
async start() {
if (this._started) {
throw new Error("StdioServerTransport already started! If using Server class, note that connect() calls start() automatically.");
}
this._started = true;
this._stdin.on("data", this._ondata);
this._stdin.on("error", this._onerror);
}
processReadBuffer() {
var _a, _b;
while (true) {
try {
const message = this._readBuffer.readMessage();
if (message === null) {
break;
}
(_a = this.onmessage) === null || _a === void 0 ? void 0 : _a.call(this, message);
}
catch (error) {
(_b = this.onerror) === null || _b === void 0 ? void 0 : _b.call(this, error);
}
}
}
async close() {
var _a;
this._stdin.off("data", this._ondata);
this._stdin.off("error", this._onerror);
this._readBuffer.clear();
(_a = this.onclose) === null || _a === void 0 ? void 0 : _a.call(this);
}
send(message) {
return new Promise((resolve) => {
const json = serializeMessage(message);
if (this._stdout.write(json)) {
resolve();
}
else {
this._stdout.once("drain", resolve);
}
});
}
}
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