StreamableHttp - Server transport with state management #553
Conversation
| # If no session ID provided but required, return error | ||
| if not request_session_id: | ||
| response = self._create_error_response( | ||
| "Bad Request: Missing session ID", |
There was a problem hiding this comment.
I get this error when I run the example server:
uv run mcp-simple-streamablehttp --port 3000 --log-level DEBUGThen
curl http://localhost:3000/mcp/ -d '
{
"jsonrpc": "2.0",
"method": "initialize",
"params": {
"protocolVersion": "2025-03-26",
"capabilities": {},
"clientInfo": {
"name": "curl-client",
"version": "1.0.0"
}
}
}' \
-H "Content-Type: application/json" \
-H "Accept: application/json, text/event-stream" \
-X POST | \
jqoutput:
{
"jsonrpc": "2.0",
"id": "server-error",
"error": {
"code": -32600,
"message": "Bad Request: Missing session ID"
}
}There was a problem hiding this comment.
But this is before I'm able to get the session from the server to start with
There was a problem hiding this comment.
Ah - I was missing the id, thats why. it mistook the message as a notification, and then didn't trigger the if is_initialization_request path. That could have a better error, but idt it should block here
|
|
||
| app = Server("mcp-streamable-http-demo") | ||
|
|
||
| @app.call_tool() |
There was a problem hiding this comment.
[nit, also could be a follow up] Would be nice to use fastmcp here - i usually end up going:
server = FastMCP(...)
...
server._mcp_server # <- to access the lower level mcp interfaceBut perhaps we should just make it easier to get to
There was a problem hiding this comment.
I think I was quite confused here, we have two folders for servers: fastmcp and servers. I was planning to add fastmcp exaple as a follow up.
fastmcp might also help with related_request_id clarity - it's hidden under log. Low level server does not have a place where we can nicely inject related_request_id
|
@jerome3o-anthropic, very good point on notification params, somehow I completely ignored that fact it's part of the spec 🙈 What do you think about using meta field to propagate |
I think I'd like to change the approach to use clean separation: #590 |
Adding support for StreamableHTTP transport transport for MCP servers, providing bidirectional communication over
HTTP with streaming support.
Features
Follow ups
#443