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improve event store interface

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ihrpr 2025-04-15 11:03:44 +01:00
commit 67a4595ae7
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1 changed files with 58 additions and 68 deletions
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49
src/server/streamableHttp.ts
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@ -1,45 +1,30 @@
import { IncomingMessage, ServerResponse } from "node:http";
import { Transport } from "../shared/transport.js";
import { isJSONRPCNotification, isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema, RequestId } from "../types.js";
import { isJSONRPCRequest, isJSONRPCResponse, JSONRPCMessage, JSONRPCMessageSchema, RequestId } from "../types.js";
import getRawBody from "raw-body";
import contentType from "content-type";
import { randomUUID } from "node:crypto";
const MAXIMUM_MESSAGE_SIZE = "4mb";
export type StreamId = string;
export type EventId = string;
/**
* Interface for resumability support via event storage
*/
export interface EventStore {
/**
* Generates a unique event ID for a given stream ID
* @param streamId The stream ID to include in the event ID
* @returns A unique event ID that includes the stream ID
*/
generateEventId(streamId: string): string;
/**
* Stores an event for later retrieval
* @param streamId ID of the stream the event belongs to
* @param message The JSON-RPC message to store
* @returns The generated event ID for the stored event
*/
storeEvent(streamId: string, message: JSONRPCMessage): Promise<string>;
storeEvent(streamId: StreamId, message: JSONRPCMessage): Promise<EventId>;
/**
* Retrieves events for a stream starting from a given event ID
* @param lastEventId The event ID to start from
* @returns Array of stored events with their event IDs
*/
getEventsAfter(lastEventId: string): Promise<Array<{ eventId: string, message: JSONRPCMessage }>>;
/**
* Extracts the stream ID from an event ID
* This is necessary for resumability to identify which stream the event belongs to
* @param eventId The event ID to extract stream ID from
* @returns The stream ID portion of the event ID
*/
getStreamIdFromEventId(eventId: string): string;
replayEventsAfter(lastEventId: EventId, { send }: {
send: (eventId: EventId, message: JSONRPCMessage) => Promise<void>
}): Promise<StreamId>;
}
/**
@ -232,12 +217,7 @@ export class StreamableHTTPServerTransport implements Transport {
if (!this._eventStore) {
return;
}
try {
const events = await this._eventStore.getEventsAfter(lastEventId);
const streamId = this._eventStore.getStreamIdFromEventId(lastEventId);
this._streamMapping.set(streamId, res);
const headers: Record<string, string> = {
"Content-Type": "text/event-stream",
"Cache-Control": "no-cache, no-transform",
@ -248,9 +228,16 @@ export class StreamableHTTPServerTransport implements Transport {
headers["mcp-session-id"] = this.sessionId;
}
res.writeHead(200, headers).flushHeaders();
for (const { eventId, message } of events) {
this.writeSSEEvent(res, message, eventId);
}
const streamId = await this._eventStore?.replayEventsAfter(lastEventId, {
send: async (eventId: string, message: JSONRPCMessage) => {
if (!this.writeSSEEvent(res, message, eventId)) {
this.onerror?.(new Error("Failed replay events"));
res.end();
}
}
});
this._streamMapping.set(streamId, res);
} catch (error) {
this.onerror?.(error as Error);
}