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Fix support for streamable-http connections.

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* In server/index.js
  - add get/post handlers for /mcp
  - amend console log on SSE connect, with deprecation message
  - add /stdio GET handler and refactored /sse GET handler to not also do stdio. Each transport has its own handler now
  - add appropriate headers to streamable-http request

* In /client/src/lib/hooks/useConnection.ts
  - in connect function
    - create server url properly based on new transport type.
This commit is contained in:
cliffhall
2025-04-21 11:34:55 -04:00
parent 6ab7ac3e1a
commit e5f6524eb6
2 changed files with 137 additions and 17 deletions
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125
server/src/index.ts
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@@ -97,7 +97,9 @@ const createTransport = async (req: express.Request): Promise<Transport> => {
console.log("Connected to SSE transport");
return transport;
} else if (transportType === "streamable-http") {
const headers: HeadersInit = {};
const headers: HeadersInit = {
Accept: "text/event-stream, application/json"
};
for (const key of STREAMABLE_HTTP_HEADERS_PASSTHROUGH) {
if (req.headers[key] === undefined) {
@@ -127,9 +129,79 @@ const createTransport = async (req: express.Request): Promise<Transport> => {
let backingServerTransport: Transport | undefined;
app.get("/sse", async (req, res) => {
app.get("/mcp", async (req, res) => {
try {
console.log("New SSE connection");
console.log("New streamable-http connection");
try {
await backingServerTransport?.close();
backingServerTransport = await createTransport(req);
} catch (error) {
if (error instanceof SseError && error.code === 401) {
console.error(
"Received 401 Unauthorized from MCP server:",
error.message,
);
res.status(401).json(error);
return;
}
throw error;
}
console.log("Connected MCP client to backing server transport");
const webAppTransport = new SSEServerTransport("/mcp", res);
webAppTransports.push(webAppTransport);
console.log("Created web app transport");
await webAppTransport.start();
if (backingServerTransport instanceof StdioClientTransport) {
backingServerTransport.stderr!.on("data", (chunk) => {
webAppTransport.send({
jsonrpc: "2.0",
method: "notifications/stderr",
params: {
content: chunk.toString(),
},
});
});
}
mcpProxy({
transportToClient: webAppTransport,
transportToServer: backingServerTransport,
});
console.log("Set up MCP proxy");
} catch (error) {
console.error("Error in /sse route:", error);
res.status(500).json(error);
}
});
app.post("/mcp", async (req, res) => {
try {
const sessionId = req.query.sessionId;
console.log(`Received message for sessionId ${sessionId}`);
const transport = webAppTransports.find((t) => t.sessionId === sessionId);
if (!transport) {
res.status(404).end("Session not found");
return;
}
await transport.handlePostMessage(req, res);
} catch (error) {
console.error("Error in /mcp route:", error);
res.status(500).json(error);
}
});
app.get("/stdio", async (req, res) => {
try {
console.log("New connection");
try {
await backingServerTransport?.close();
@@ -150,15 +222,12 @@ app.get("/sse", async (req, res) => {
console.log("Connected MCP client to backing server transport");
const webAppTransport = new SSEServerTransport("/message", res);
console.log("Created web app transport");
webAppTransports.push(webAppTransport);
console.log("Created web app transport");
await webAppTransport.start();
if (backingServerTransport instanceof StdioClientTransport) {
backingServerTransport.stderr!.on("data", (chunk) => {
(backingServerTransport as StdioClientTransport).stderr!.on("data", (chunk) => {
webAppTransport.send({
jsonrpc: "2.0",
method: "notifications/stderr",
@@ -167,8 +236,48 @@ app.get("/sse", async (req, res) => {
},
});
});
mcpProxy({
transportToClient: webAppTransport,
transportToServer: backingServerTransport,
});
console.log("Set up MCP proxy");
} catch (error) {
console.error("Error in /stdio route:", error);
res.status(500).json(error);
}
});
app.get("/sse", async (req, res) => {
try {
console.log("New SSE connection. NOTE: The sse transport is deprecated and has been replaced by streamable-http");
try {
await backingServerTransport?.close();
backingServerTransport = await createTransport(req);
} catch (error) {
if (error instanceof SseError && error.code === 401) {
console.error(
"Received 401 Unauthorized from MCP server:",
error.message,
);
res.status(401).json(error);
return;
}
throw error;
}
console.log("Connected MCP client to backing server transport");
const webAppTransport = new SSEServerTransport("/message", res);
webAppTransports.push(webAppTransport);
console.log("Created web app transport");
await webAppTransport.start();
mcpProxy({
transportToClient: webAppTransport,
transportToServer: backingServerTransport,