@cyanheads/pubmed-mcp-server
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Production-ready PubMed Model Context Protocol (MCP) server that empowers AI agents and research tools with comprehensive access to PubMed's article database. Enables advanced, automated LLM workflows for searching, retrieving, analyzing, and visualizing
66 lines • 2.86 kB
JavaScript
/**
* @fileoverview Hono middleware for handling MCP transport logic.
* This middleware encapsulates the logic for processing MCP requests,
* delegating to the appropriate transport manager, and preparing the
* response for Hono to send.
* @module src/mcp-server/transports/http/mcpTransportMiddleware
*/
import { isInitializeRequest } from "@modelcontextprotocol/sdk/types.js";
import { createMiddleware } from "hono/factory";
import { config } from "../../../config/index.js";
import { requestContextService } from "../../../utils/index.js";
import { StatelessTransportManager } from "../core/statelessTransportManager.js";
/**
* Converts a Fetch API Headers object to Node.js IncomingHttpHeaders.
* @param headers - The Headers object to convert.
* @returns An object compatible with IncomingHttpHeaders.
*/
function toIncomingHttpHeaders(headers) {
const result = {};
headers.forEach((value, key) => {
result[key] = value;
});
return result;
}
/**
* Handles a stateless request by creating an ephemeral transport manager.
* @param createServerInstanceFn - Function to create an McpServer instance.
* @param headers - The request headers.
* @param body - The request body.
* @param context - The request context.
* @returns A promise resolving with the transport response.
*/
async function handleStatelessRequest(createServerInstanceFn, headers, body, context) {
const statelessManager = new StatelessTransportManager(createServerInstanceFn);
return statelessManager.handleRequest(toIncomingHttpHeaders(headers), body, context);
}
export const mcpTransportMiddleware = (transportManager, createServerInstanceFn) => {
return createMiddleware(async (c, next) => {
const sessionId = c.req.header("mcp-session-id");
const context = requestContextService.createRequestContext({
operation: "mcpTransportMiddleware",
sessionId,
});
const body = await c.req.json();
let response;
if (isInitializeRequest(body)) {
if (config.mcpSessionMode === "stateless") {
response = await handleStatelessRequest(createServerInstanceFn, c.req.raw.headers, body, context);
}
else {
response = await transportManager.initializeAndHandle(toIncomingHttpHeaders(c.req.raw.headers), body, context);
}
}
else {
if (sessionId) {
response = await transportManager.handleRequest(toIncomingHttpHeaders(c.req.raw.headers), body, context, sessionId);
}
else {
response = await handleStatelessRequest(createServerInstanceFn, c.req.raw.headers, body, context);
}
}
c.set("mcpResponse", response);
await next();
});
};
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