LangServe 部署：把链变成 API

// server.ts
import { addRoute } from "langserve";
import express from "express";
import { ChatOpenAI } from "@langchain/openai";
import { ChatPromptTemplate } from "@langchain/core/prompts";
import { StringOutputParser } from "@langchain/core/output_parsers";
 
const app = express();
 
const chain = ChatPromptTemplate.fromTemplate("用中文回答：{question}")
  .pipe(new ChatOpenAI({ model: "gpt-4o-mini" }))
  .pipe(new StringOutputParser());
 
addRoute(app, "/chat", chain, { playground: true });
 
app.listen(8000, () => console.log("http://localhost:8000/chat/playground"));

import { RemoteRunnable } from "@langchain/core/runnables";
 
const remote = new RemoteRunnable({
  url: "http://localhost:8000/chat",
});
 
const res = await remote.invoke({ question: "什么是 RAG？" });