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Okay, I can help you understand how to use the TypeScript SDK to create different MCP (Mesh Configuration Protocol) servers. However, I need a little more context to give you the *most* helpful answer. Specifically, tell me: 1. **Which MCP SDK are you using?** There are several possibilities, including: * **Istio's MCP SDK (likely part of the `envoyproxy/go-control-plane` project, but you'd be using the TypeScript bindings).** This is the most common use case if you're working with Istio or Envoy. * **A custom MCP implementation.** If you're building your own MCP server from scratch, you'll need to define your own data structures and server logic. * **Another MCP SDK.** There might be other, less common, MCP SDKs available. 2. **What kind of MCP server do you want to create?** What specific resources will it serve? For example: * **Route Configuration (RDS) server:** Serves route configurations to Envoy proxies. * **Cluster Configuration (CDS) server:** Serves cluster definitions to Envoy proxies. * **Listener Configuration (LDS) server:** Serves listener configurations to Envoy proxies. * **Endpoint Discovery Service (EDS) server:** Serves endpoint information to Envoy proxies. * **A custom resource server:** Serves your own custom resource types. 3. **What is your desired level of detail?** Do you want: * **A high-level overview of the process?** * **Example code snippets?** * **A complete, runnable example?** (This would be more complex and require more information from you.) **General Steps (Assuming Istio/Envoy MCP):** Here's a general outline of the steps involved in creating an MCP server using a TypeScript SDK (assuming it's based on the Envoy/Istio MCP protocol): 1. **Install the Necessary Packages:** You'll need to install the appropriate TypeScript packages. This will likely involve: * The core gRPC library for TypeScript (`@grpc/grpc-js` or similar). * The generated TypeScript code from the Protocol Buffers (`.proto`) definitions for the MCP resources you want to serve (e.g., `envoy.config.route.v3`, `envoy.config.cluster.v3`, etc.). You'll typically use `protoc` (the Protocol Buffer compiler) and a TypeScript plugin to generate these files. * Potentially, a library that provides helper functions for working with MCP. ```bash npm install @grpc/grpc-js google-protobuf # And potentially other packages depending on your setup ``` 2. **Generate TypeScript Code from Protocol Buffers:** You'll need to obtain the `.proto` files that define the MCP resources (e.g., from the `envoyproxy/go-control-plane` repository or your own custom definitions). Then, use `protoc` to generate TypeScript code from these files. This will create the TypeScript classes that represent the resource types. Example `protoc` command (you'll need to adjust this based on your `.proto` file locations and plugin configuration): ```bash protoc --plugin=protoc-gen-ts=./node_modules/.bin/protoc-gen-ts --ts_out=. your_mcp_resource.proto ``` 3. **Implement the gRPC Service:** Create a TypeScript class that implements the gRPC service defined in the `.proto` files. This class will have methods that correspond to the MCP endpoints (e.g., `StreamRoutes`, `StreamClusters`, etc.). These methods will receive requests from Envoy proxies and return the appropriate resource configurations. 4. **Handle the MCP Stream:** The core of an MCP server is handling the bidirectional gRPC stream. Your service implementation will need to: * Receive `DiscoveryRequest` messages from the client (Envoy proxy). * Process the request, determining which resources the client is requesting. * Fetch the appropriate resource configurations from your data store (e.g., a database, a configuration file, or in-memory data). * Construct `DiscoveryResponse` messages containing the resource configurations. * Send the `DiscoveryResponse` messages back to the client. * Handle errors and stream termination gracefully. 5. **Manage Resource Versions (Important for Updates):** MCP uses versioning to ensure that clients receive consistent updates. You'll need to track the versions of your resources and include them in the `DiscoveryResponse` messages. When a client sends a `DiscoveryRequest`, it will include the version of the resources it currently has. Your server should only send updates if the client's version is out of date. 6. **Implement a Data Store (Configuration Source):** You'll need a way to store and manage the resource configurations that your MCP server serves. This could be a simple configuration file, a database, or a more complex configuration management system. 7. **Start the gRPC Server:** Use the gRPC library to start a gRPC server and register your service implementation with it. The server will listen for incoming connections from Envoy proxies. 8. **Configure Envoy to Use Your MCP Server:** Configure your Envoy proxies to connect to your MCP server. This will typically involve specifying the server's address and port in the Envoy configuration. **Example (Conceptual - Requires Adaptation):** ```typescript // Assuming you've generated TypeScript code from your .proto files // import { RouteDiscoveryServiceService, RouteDiscoveryServiceHandlers } from './route_discovery_grpc_pb'; // import { DiscoveryRequest, DiscoveryResponse } from './discovery_pb'; import * as grpc from '@grpc/grpc-js'; // Replace with your actual generated code interface DiscoveryRequest { versionInfo: string; node: any; // Replace with your Node type resourceNames: string[]; typeUrl: string; responseNonce: string; errorDetail: any; // Replace with your Status type } interface DiscoveryResponse { versionInfo: string; resources: any[]; // Replace with your Resource type typeUrl: string; nonce: string; controlPlane: any; // Replace with your ControlPlane type } interface RouteDiscoveryServiceHandlers { streamRoutes: grpc.ServerDuplexStream<DiscoveryRequest, DiscoveryResponse>; } class RouteDiscoveryServiceImpl implements RouteDiscoveryServiceHandlers { streamRoutes(stream: grpc.ServerDuplexStream<DiscoveryRequest, DiscoveryResponse>): void { stream.on('data', (request: DiscoveryRequest) => { console.log('Received request:', request); // Fetch route configurations based on the request const routes = this.fetchRoutes(request); // Construct the DiscoveryResponse const response: DiscoveryResponse = { versionInfo: 'v1', // Replace with your versioning logic resources: routes, typeUrl: 'envoy.config.route.v3.RouteConfiguration', // Replace with your resource type URL nonce: 'some-nonce', // Generate a unique nonce controlPlane: null, // Replace if you have control plane info }; stream.write(response); }); stream.on('end', () => { console.log('Stream ended'); stream.end(); }); stream.on('error', (err) => { console.error('Stream error:', err); stream.end(); }); } private fetchRoutes(request: DiscoveryRequest): any[] { // Implement your logic to fetch route configurations // based on the request parameters (e.g., resourceNames, versionInfo) // This is where you would access your data store. console.log("fetching routes"); return [ { name: 'route1', domains: ['example.com'] }, { name: 'route2', domains: ['test.com'] }, ]; // Replace with actual route configurations } } function main() { const server = new grpc.Server(); // server.addService(RouteDiscoveryServiceService, new RouteDiscoveryServiceImpl()); server.addService({streamRoutes: {path: "/envoy.service.discovery.v3.RouteDiscoveryService/StreamRoutes", requestStream: true, responseStream: true, requestSerialize: (arg: any) => Buffer.from(JSON.stringify(arg)), requestDeserialize: (arg: Buffer) => JSON.parse(arg.toString()), responseSerialize: (arg: any) => Buffer.from(JSON.stringify(arg)), responseDeserialize: (arg: Buffer) => JSON.parse(arg.toString())}}, new RouteDiscoveryServiceImpl()); server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), (err, port) => { if (err) { console.error('Failed to bind:', err); return; } console.log(`Server listening on port ${port}`); server.start(); }); } main(); ``` **Important Considerations:** * **Error Handling:** Implement robust error handling to gracefully handle unexpected situations. * **Logging:** Add logging to help you debug and monitor your MCP server. * **Security:** Secure your gRPC server using TLS/SSL. * **Scalability:** Consider the scalability of your MCP server, especially if you're serving a large number of Envoy proxies. * **Testing:** Thoroughly test your MCP server to ensure that it's working correctly. **Next Steps:** 1. **Tell me which MCP SDK you're using.** 2. **Tell me what kind of MCP server you want to create.** 3. **Tell me your desired level of detail.** Once I have this information, I can provide you with more specific and helpful guidance.