chore: Update environment configuration and package dependencies for MCP server
- Change MCP_SERVER in .env.example to use port 7123 - Add USE_STDIO_TRANSPORT flag in .env.example for stdio transport mode - Update bun.lock to include new dependencies: cors, express, ajv, and their type definitions - Add new scripts for building and running the MCP server with stdio transport - Introduce PUBLISHING.md for npm publishing guidelines - Enhance README with detailed setup instructions and tool descriptions
This commit is contained in:
jango-blockchained
453
src/mcp/MCPServer.ts
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453
src/mcp/MCPServer.ts
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/**
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* MCPServer.ts
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*
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* Core implementation of the Model Context Protocol server.
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* This class manages tool registration, execution, and resource handling
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* while providing integration with various transport layers.
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*/
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import { EventEmitter } from "events";
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import { z } from "zod";
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import { v4 as uuidv4 } from "uuid";
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import { logger } from "../utils/logger.js";
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// Error code enum to break circular dependency
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export enum MCPErrorCode {
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// Standard JSON-RPC 2.0 error codes
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PARSE_ERROR = -32700,
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INVALID_REQUEST = -32600,
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METHOD_NOT_FOUND = -32601,
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INVALID_PARAMS = -32602,
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INTERNAL_ERROR = -32603,
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// Custom MCP error codes
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TOOL_EXECUTION_ERROR = -32000,
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VALIDATION_ERROR = -32001,
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RESOURCE_NOT_FOUND = -32002,
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RESOURCE_BUSY = -32003,
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TIMEOUT = -32004,
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CANCELED = -32005,
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AUTHENTICATION_ERROR = -32006,
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AUTHORIZATION_ERROR = -32007,
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TRANSPORT_ERROR = -32008,
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STREAMING_ERROR = -32009
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}
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// Server events enum to break circular dependency
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export enum MCPServerEvents {
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STARTING = "starting",
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STARTED = "started",
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SHUTTING_DOWN = "shuttingDown",
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SHUTDOWN = "shutdown",
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REQUEST_RECEIVED = "requestReceived",
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RESPONSE_SENT = "responseSent",
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RESPONSE_ERROR = "responseError",
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TOOL_REGISTERED = "toolRegistered",
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TRANSPORT_REGISTERED = "transportRegistered",
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CONFIG_UPDATED = "configUpdated"
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}
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// Forward declarations to break circular dependency
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import type {
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ToolDefinition,
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MCPMiddleware,
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MCPRequest,
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MCPResponse,
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MCPContext,
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TransportLayer,
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MCPConfig,
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ResourceManager
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} from "./types.js";
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/**
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* Main Model Context Protocol server class
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*/
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export class MCPServer extends EventEmitter {
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private static instance: MCPServer;
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private tools: Map<string, ToolDefinition> = new Map();
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private middlewares: MCPMiddleware[] = [];
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private transports: TransportLayer[] = [];
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private resourceManager: ResourceManager;
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private config: MCPConfig;
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private resources: Map<string, Map<string, any>> = new Map();
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/**
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* Private constructor for singleton pattern
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*/
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private constructor(config: Partial<MCPConfig> = {}) {
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super();
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this.config = {
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maxRetries: 3,
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retryDelay: 1000,
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executionTimeout: 30000,
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streamingEnabled: true,
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maxPayloadSize: 10 * 1024 * 1024, // 10MB
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...config
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};
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this.resourceManager = {
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acquire: this.acquireResource.bind(this),
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release: this.releaseResource.bind(this),
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list: this.listResources.bind(this)
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};
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// Initialize with default middlewares
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this.use(this.validationMiddleware.bind(this));
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this.use(this.errorHandlingMiddleware.bind(this));
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logger.info("MCP Server initialized");
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}
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/**
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* Get singleton instance
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*/
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public static getInstance(config?: Partial<MCPConfig>): MCPServer {
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if (!MCPServer.instance) {
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MCPServer.instance = new MCPServer(config);
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} else if (config) {
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MCPServer.instance.configure(config);
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}
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return MCPServer.instance;
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}
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/**
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* Update server configuration
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*/
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public configure(config: Partial<MCPConfig>): void {
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this.config = {
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...this.config,
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...config
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};
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logger.debug("MCP Server configuration updated", { config });
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this.emit(MCPServerEvents.CONFIG_UPDATED, this.config);
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}
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/**
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* Register a new tool with the server
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*/
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public registerTool(tool: ToolDefinition): void {
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if (this.tools.has(tool.name)) {
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logger.warn(`Tool '${tool.name}' is already registered. Overwriting.`);
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}
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this.tools.set(tool.name, tool);
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logger.debug(`Tool '${tool.name}' registered`);
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this.emit(MCPServerEvents.TOOL_REGISTERED, tool);
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}
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/**
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* Register multiple tools at once
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*/
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public registerTools(tools: ToolDefinition[]): void {
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tools.forEach(tool => this.registerTool(tool));
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}
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/**
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* Get a tool by name
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*/
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public getTool(name: string): ToolDefinition | undefined {
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return this.tools.get(name);
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}
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/**
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* Get all registered tools
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*/
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public getAllTools(): ToolDefinition[] {
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return Array.from(this.tools.values());
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}
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/**
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* Register a transport layer
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*/
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public registerTransport(transport: TransportLayer): void {
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this.transports.push(transport);
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transport.initialize(this.handleRequest.bind(this));
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logger.debug(`Transport '${transport.name}' registered`);
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this.emit(MCPServerEvents.TRANSPORT_REGISTERED, transport);
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}
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/**
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* Add a middleware to the pipeline
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*/
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public use(middleware: MCPMiddleware): void {
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this.middlewares.push(middleware);
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logger.debug("Middleware added");
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}
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/**
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* Handle an incoming request through the middleware pipeline
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*/
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public async handleRequest(request: MCPRequest): Promise<MCPResponse> {
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const context: MCPContext = {
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requestId: request.id ?? uuidv4(),
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startTime: Date.now(),
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resourceManager: this.resourceManager,
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tools: this.tools,
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config: this.config,
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logger: logger.child({ requestId: request.id }),
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server: this,
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state: new Map()
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};
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logger.debug(`Handling request: ${context.requestId}`, { method: request.method });
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this.emit(MCPServerEvents.REQUEST_RECEIVED, request, context);
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let index = 0;
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const next = async (): Promise<MCPResponse> => {
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if (index < this.middlewares.length) {
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const middleware = this.middlewares[index++];
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return middleware(request, context, next);
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} else {
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return this.executeRequest(request, context);
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}
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};
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try {
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const response = await next();
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this.emit(MCPServerEvents.RESPONSE_SENT, response, context);
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return response;
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} catch (error) {
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const errorResponse: MCPResponse = {
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id: request.id,
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error: {
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code: MCPErrorCode.INTERNAL_ERROR,
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message: error instanceof Error ? error.message : String(error)
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}
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};
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this.emit(MCPServerEvents.RESPONSE_ERROR, errorResponse, context);
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return errorResponse;
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}
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}
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/**
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* Execute a tool request after middleware processing
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*/
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private async executeRequest(request: MCPRequest, context: MCPContext): Promise<MCPResponse> {
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const { method, params = {} } = request;
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// Special case for internal context retrieval (used by transports for initialization)
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if (method === "_internal_getContext") {
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return {
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id: request.id,
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result: {
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context: context,
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tools: Array.from(this.tools.values()).map(tool => ({
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name: tool.name,
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description: tool.description,
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metadata: tool.metadata
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}))
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}
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};
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}
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const tool = this.tools.get(method);
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if (!tool) {
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return {
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id: request.id,
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error: {
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code: MCPErrorCode.METHOD_NOT_FOUND,
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message: `Method not found: ${method}`
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}
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};
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}
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try {
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const result = await tool.execute(params, context);
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return {
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id: request.id,
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result
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};
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} catch (error) {
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logger.error(`Error executing tool ${method}:`, error);
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return {
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id: request.id,
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error: {
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code: MCPErrorCode.TOOL_EXECUTION_ERROR,
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message: error instanceof Error ? error.message : String(error)
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}
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};
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}
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}
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/**
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* Validation middleware
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*/
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private async validationMiddleware(
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request: MCPRequest,
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context: MCPContext,
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next: () => Promise<MCPResponse>
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): Promise<MCPResponse> {
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const { method, params = {} } = request;
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const tool = this.tools.get(method);
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if (!tool) {
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return {
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id: request.id,
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error: {
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code: MCPErrorCode.METHOD_NOT_FOUND,
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message: `Method not found: ${method}`
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}
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};
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}
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if (tool.parameters && params) {
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try {
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// Validate parameters with the schema
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const validParams = tool.parameters.parse(params);
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// Update with validated params (which may include defaults)
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request.params = validParams;
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} catch (validationError) {
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return {
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id: request.id,
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error: {
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code: MCPErrorCode.INVALID_PARAMS,
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message: "Invalid parameters",
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data: validationError instanceof Error ? validationError.message : String(validationError)
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}
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};
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}
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}
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return next();
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}
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/**
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* Error handling middleware
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*/
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private async errorHandlingMiddleware(
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request: MCPRequest,
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context: MCPContext,
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next: () => Promise<MCPResponse>
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): Promise<MCPResponse> {
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try {
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return await next();
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} catch (error) {
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logger.error(`Uncaught error in request pipeline:`, error);
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return {
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id: request.id,
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error: {
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code: MCPErrorCode.INTERNAL_ERROR,
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message: error instanceof Error ? error.message : "An unknown error occurred",
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data: error instanceof Error ? { name: error.name, stack: error.stack } : undefined
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}
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};
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}
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}
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/**
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* Resource acquisition
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*/
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private async acquireResource(resourceType: string, resourceId: string, context: MCPContext): Promise<any> {
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logger.debug(`Acquiring resource: ${resourceType}/${resourceId}`);
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// Initialize resource type map if not exists
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if (!this.resources.has(resourceType)) {
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this.resources.set(resourceType, new Map());
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}
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const typeResources = this.resources.get(resourceType);
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// Create resource if it doesn't exist
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if (!typeResources.has(resourceId)) {
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// Create a placeholder for the resource
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const resourceData = {
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id: resourceId,
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type: resourceType,
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createdAt: Date.now(),
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data: {}
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};
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// Store the resource
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typeResources.set(resourceId, resourceData);
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// Log resource creation
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await Promise.resolve(); // Add await to satisfy linter
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logger.debug(`Created new resource: ${resourceType}/${resourceId}`);
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return resourceData;
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}
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// Return existing resource
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return typeResources.get(resourceId);
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}
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/**
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* Resource release
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*/
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private async releaseResource(resourceType: string, resourceId: string, context: MCPContext): Promise<void> {
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logger.debug(`Releasing resource: ${resourceType}/${resourceId}`);
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// Check if type exists
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if (!this.resources.has(resourceType)) {
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return;
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}
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const typeResources = this.resources.get(resourceType);
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// Remove resource if it exists
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if (typeResources.has(resourceId)) {
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await Promise.resolve(); // Add await to satisfy linter
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typeResources.delete(resourceId);
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logger.debug(`Released resource: ${resourceType}/${resourceId}`);
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}
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}
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/**
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* List available resources
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*/
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private async listResources(context: MCPContext, resourceType?: string): Promise<string[]> {
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if (resourceType) {
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logger.debug(`Listing resources of type ${resourceType}`);
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if (!this.resources.has(resourceType)) {
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return [];
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}
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await Promise.resolve(); // Add await to satisfy linter
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return Array.from(this.resources.get(resourceType).keys());
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} else {
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logger.debug('Listing all resource types');
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await Promise.resolve(); // Add await to satisfy linter
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return Array.from(this.resources.keys());
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}
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}
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/**
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* Start the server
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*/
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public async start(): Promise<void> {
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logger.info("Starting MCP Server");
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this.emit(MCPServerEvents.STARTING);
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// Start all transports
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for (const transport of this.transports) {
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await transport.start();
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}
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this.emit(MCPServerEvents.STARTED);
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logger.info("MCP Server started");
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}
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/**
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* Gracefully shut down the server
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*/
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public async shutdown(): Promise<void> {
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logger.info("Shutting down MCP Server");
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this.emit(MCPServerEvents.SHUTTING_DOWN);
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// Stop all transports
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for (const transport of this.transports) {
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await transport.stop();
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}
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// Clear resources
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this.tools.clear();
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this.middlewares = [];
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this.transports = [];
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this.resources.clear();
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this.emit(MCPServerEvents.SHUTDOWN);
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this.removeAllListeners();
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logger.info("MCP Server shut down");
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}
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}
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