import { LoggingLevel } from "@modelcontextprotocol/sdk/types.js";
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
// Map session ID to the interval for sending logging messages to the client
const logsUpdateIntervals: Map<string | undefined, NodeJS.Timeout | undefined> =
new Map<string | undefined, NodeJS.Timeout | undefined>();
/**
* Initiates a simulated logging process by sending random log messages to the client at a
* fixed interval. Each log message contains a random logging level and optional session ID.
*
* @param {McpServer} server - The server instance responsible for handling the logging messages.
* @param {string | undefined} sessionId - An optional identifier for the session. If provided,
* the session ID will be appended to log messages.
*/
export const beginSimulatedLogging = (
server: McpServer,
sessionId: string | undefined
) => {
const maybeAppendSessionId = sessionId ? ` - SessionId ${sessionId}` : "";
const messages: { level: LoggingLevel; data: string }[] = [
{ level: "debug", data: `Debug-level message${maybeAppendSessionId}` },
{ level: "info", data: `Info-level message${maybeAppendSessionId}` },
{ level: "notice", data: `Notice-level message${maybeAppendSessionId}` },
{
level: "warning",
data: `Warning-level message${maybeAppendSessionId}`,
},
{ level: "error", data: `Error-level message${maybeAppendSessionId}` },
{
level: "critical",
data: `Critical-level message${maybeAppendSessionId}`,
},
{ level: "alert", data: `Alert level-message${maybeAppendSessionId}` },
{
level: "emergency",
data: `Emergency-level message${maybeAppendSessionId}`,
},
];
/**
* Send a simulated logging message to the client
*/
const sendSimulatedLoggingMessage = async (sessionId: string | undefined) => {
// By using the `sendLoggingMessage` function to send the message, we
// ensure that the client's chosen logging level will be respected
await server.sendLoggingMessage(
messages[Math.floor(Math.random() * messages.length)],
sessionId
);
};
// Set the interval to send later logging messages to this client
if (!logsUpdateIntervals.has(sessionId)) {
// Send once immediately
sendSimulatedLoggingMessage(sessionId);
// Send a randomly-leveled log message every 5 seconds
logsUpdateIntervals.set(
sessionId,
setInterval(() => sendSimulatedLoggingMessage(sessionId), 5000)
);
}
};
/**
* Stops the simulated logging process for a given session.
*
* This function halts the periodic logging updates associated with the specified
* session ID by clearing the interval and removing the session's tracking
* reference. Session ID can be undefined for stdio.
*
* @param {string} [sessionId] - The optional unique identifier of the session.
*/
export const stopSimulatedLogging = (sessionId?: string) => {
// Remove active intervals
if (logsUpdateIntervals.has(sessionId)) {
const logsUpdateInterval = logsUpdateIntervals.get(sessionId);
clearInterval(logsUpdateInterval);
logsUpdateIntervals.delete(sessionId);
}
};
