feat: add streamable http [MCP-42] #361

fmenezes · 2025-07-14T15:57:54Z

Proposed changes

Introduces Streamable HTTP transport; No authentication or authorization was implemented.

Note: this is a feature branch, every single individual change was approved on each PR.

Checklist

I have signed the MongoDB CLA

coveralls · 2025-07-14T16:06:04Z

Pull Request Test Coverage Report for Build 16422846497

Details

238 of 402 (59.2%) changed or added relevant lines in 10 files are covered.
No unchanged relevant lines lost coverage.
Overall coverage decreased (-1.6%) to 80.243%

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/server.ts	24	36	66.67%
src/transports/stdio.ts	8	21	38.1%
src/index.ts	0	28	0.0%
src/common/sessionStore.ts	51	92	55.43%
src/transports/streamableHttp.ts	88	158	55.7%

Totals
Change from base Build 16373544917:	-1.6%
Covered Lines:	3099
Relevant Lines:	3826

💛 - Coveralls

Copilot

Pull Request Overview

This PR introduces streamable HTTP transport functionality to the MongoDB MCP Server, allowing it to run as an HTTP server in addition to the existing stdio transport. The implementation includes session management with timeout handling and configurable logging options.

Adds StreamableHttpRunner with Express-based HTTP server and session management
Refactors transport layer with base class and configurable runner selection
Introduces comprehensive timeout management for HTTP sessions with cleanup

Reviewed Changes

Copilot reviewed 24 out of 25 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/transports/streamableHttp.ts	New HTTP transport implementation with session management and Express server
src/transports/stdio.ts	Refactored stdio transport into runner pattern with base class
src/transports/base.ts	Abstract base class for transport runners
src/common/timeoutManager.ts	New timeout management utility for session cleanup
src/common/sessionStore.ts	HTTP session storage and lifecycle management
src/common/config.ts	Enhanced configuration with HTTP and logging options
src/server.ts	Refactored server initialization and validation logic
src/index.ts	Simplified main entry point with transport runner selection
tests/integration/transports/streamableHttp.test.ts	Integration tests for HTTP transport
tests/integration/transports/stdio.test.ts	Integration tests for stdio transport
tests/unit/common/timeoutManager.test.ts	Unit tests for timeout manager

Copilot · 2025-07-21T11:00:30Z

src/common/timeoutManager.ts

+        if (this.callback) {
+            try {
+                await this.callback();
+            } catch (error: unknown) {
+                this.onerror?.(error);
+            }


The runCallback method checks if 'this.callback' exists, but the callback is marked as 'readonly' and provided in the constructor, so this check is unnecessary and adds complexity.

Suggested change

if (this.callback) {

try {

await this.callback();

} catch (error: unknown) {

this.onerror?.(error);

}

try {

await this.callback();

} catch (error: unknown) {

this.onerror?.(error);

Copilot · 2025-07-21T11:00:30Z

src/common/sessionStore.ts

+        const logger = new McpLogger(session.mcpServer);
+        logger.info(


Creating a new McpLogger instance for each notification is inefficient. Consider creating the logger once and reusing it, or passing it as a dependency.

Suggested change

const logger = new McpLogger(session.mcpServer);

logger.info(

session.logger.info(

agreed, we should create a logger and store it inside the our session map

Copilot · 2025-07-21T11:00:30Z

src/common/sessionStore.ts

+            const logger = new McpLogger(mcpServer);
+            logger.info(


Creating a new McpLogger instance inside the timeout callback is inefficient and could be problematic if called multiple times. Consider creating the logger once and reusing it.

Suggested change

const logger = new McpLogger(mcpServer);

logger.info(

this.sessions[sessionId].logger.info(

gagik

Going to be focused on some technical writing today but just some initial review on first part of the changes

gagik · 2025-07-21T11:16:52Z

src/common/sessionStore.ts

+    private sendNotification(sessionId: string): void {
+        const session = this.sessions[sessionId];
+        if (!session) {
+            return;


nit: maybe we should log a warning here?

gagik · 2025-07-21T11:17:17Z

src/common/sessionStore.ts

+        const logger = new McpLogger(session.mcpServer);
+        logger.info(


agreed, we should create a logger and store it inside the our session map

gagik · 2025-07-21T11:19:57Z

src/common/sessionStore.ts

+            const logger = new McpLogger(mcpServer);
+            logger.info(


gagik · 2025-07-21T11:25:52Z

src/common/timeoutManager.ts

+     * Resets the timeout.
+     */
+    reset() {


Suggested change

* Resets the timeout.

*/

reset() {

* Restarts the timeout.

*/

restart() {

Just to better differentiate from clear as it's not clear that the initial state has the timeout started already

gagik · 2025-07-21T11:26:43Z

src/common/timeoutManager.ts

+     * Runs the callback function.
+     */
+    private async runCallback() {
+        if (this.callback) {


this.callback is always defined right? this is not needed

src/common/timeoutManager.ts

gagik · 2025-07-21T11:45:23Z

src/common/timeoutManager.ts

+        if (timeoutMS <= 0) {
+            throw new Error("timeoutMS must be greater than 0");
+        }
+        this.reset();


we should not have side-effects in constructors. I think this whole helper can be better represented as a single function.

type ManagedTimeout = { cancel: () => void; restart: () => void; }; export function setManagedTimeout( callback: () => Promise<void> | void, timeoutMS: number, { onError }: { onError?: (error: unknown) => void } ) { const wrappedCallback = () => { try { await this.callback(); } catch (error: unknown) { onError?.(error); } }; let timeout = setTimeout(wrappedCallback, timeoutMS); const cancel = () => { cancelTimeout(timeout); timeout = undefined; }; const restart = () => { cancel(); timeout = setTimeout(wrappedCallback, timeoutMS); } return { cancel, restart }; }

gagik · 2025-07-21T11:49:01Z

src/server.ts

@@ -186,6 +189,35 @@ export class Server {
    }

    private async validateConfig(): Promise<void> {
+        const transport = this.userConfig.transport as string;


are these type casts needed?

That is the way I've found to validate it.

The problem here is as far as we are concerned, the possible values are predefined, so the literal types make sense, but the inputs are cli args or env vars, which are basically strings that can contain any values.

fmenezes · 2025-07-21T13:41:48Z

@gagik I'm addressing all of these at #386, if you're happy with the changes, would you approve it?

thanks!

fmenezes · 2025-07-21T16:45:54Z

@gagik I've merged the PR according to your comments, would take another look?

feat: add streamable http [MCP-55] (#359)

ff982e0

test: add streamable http tests [MCP-60] (#362)

2c21af3

fmenezes changed the title ~~feat: add streamable http [MCP-43]~~ feat: add streamable http [MCP-42] Jul 15, 2025

Merge branch 'main' into MCP-42

17b149c

fmenezes force-pushed the MCP-42 branch from c86dac0 to 17b149c Compare July 15, 2025 14:17

fmenezes added 5 commits July 15, 2025 18:24

refactor: move http server (#377)

db23253

Merge branch 'main' into MCP-42

b7c616a

feat: add session management for streamableHttp [MCP-52] (#379)

ac40e8a

chore: add transport to telemetry [MCP-62] (#382)

427663f

Merge branch 'main' into MCP-42

5058fa6

fmenezes mentioned this pull request Jul 18, 2025

feat: add HTTP/SSE transport support and document usage in Quick Start #257

Closed

feat: add client idle timeout [MCP-57] (#383)

1297ed9

fmenezes marked this pull request as ready for review July 21, 2025 10:59

Copilot AI review requested due to automatic review settings July 21, 2025 10:59

fmenezes requested a review from a team as a code owner July 21, 2025 10:59

Copilot AI reviewed Jul 21, 2025

View reviewed changes

blva requested a review from gagik July 21, 2025 11:02

gagik requested changes Jul 21, 2025

View reviewed changes

fmenezes added a commit that referenced this pull request Jul 21, 2025

chore: address comments from #361

7d3acf7

fmenezes mentioned this pull request Jul 21, 2025

chore: address comments from #361 #386

Merged

1 task

chore: address comments from #361 (#386)

3ba8a4a

		const logger = new McpLogger(session.mcpServer);
		logger.info(

	const logger = new McpLogger(session.mcpServer);
	logger.info(
	session.logger.info(

	const logger = new McpLogger(mcpServer);
	logger.info(
	this.sessions[sessionId].logger.info(

feat: add streamable http [MCP-42] #361

Are you sure you want to change the base?

feat: add streamable http [MCP-42] #361

Conversation

fmenezes commented Jul 14, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Proposed changes

Checklist

Uh oh!

coveralls commented Jul 14, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Pull Request Test Coverage Report for Build 16422846497

Details

💛 - Coveralls

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull Request Overview

Reviewed Changes

Uh oh!

Copilot AI Jul 21, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jul 21, 2025

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jul 21, 2025

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

gagik left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

fmenezes commented Jul 21, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

fmenezes commented Jul 21, 2025

Uh oh!

Uh oh!

fmenezes commented Jul 14, 2025 •

edited

Loading

coveralls commented Jul 14, 2025 •

edited

Loading

fmenezes commented Jul 21, 2025 •

edited

Loading