mcp_demonstration by Pvbhat123 - MCP Server

Standard MCP Implementation with JSON-RPC

This is a standard-compliant Model Context Protocol (MCP) implementation using JSON-RPC 2.0 protocol.

Architecture

1. MCP Server (Port 4001)

Implements MongoDB operations as MCP tools
Uses JSON-RPC 2.0 protocol
Supports standard MCP methods: initialize, tools/list, tools/call
Proper error handling with standard error codes

2. MCP Client (Port 4002)

Acts as orchestrator between Host and Server
Maintains tool registry from multiple servers
Routes tool calls using JSON-RPC protocol
Supports server initialization handshake

3. MCP Host (Interactive CLI)

User interface with Gemini AI integration
Communicates via JSON-RPC with the Client
Processes natural language queries
Formats results for user consumption

Key Differences from REST Implementation

Protocol: Uses JSON-RPC 2.0 instead of REST

Message Format: All requests/responses follow JSON-RPC envelope:

{
  "jsonrpc": "2.0",
  "method": "method_name",
  "params": {},
  "id": "unique_id"
}

Error Handling: Standard JSON-RPC error codes
Single Endpoint: All communication through /rpc endpoint
Request Correlation: Uses request IDs for tracking
Initialization: Proper protocol handshake between components

Setup Instructions

Prerequisites

Node.js installed
MongoDB running on localhost:27017
Gemini API key

Installation

Install dependencies for each component:

cd mcp_standard/mcp_server
npm install

cd ../mcp_client
npm install

cd ../mcp_host
npm install

Set up environment variables: Create a .env file in mcp_standard/mcp_host/:
```
GEMINI_API_KEY=your-gemini-api-key
```

Running the System

Start each component in separate terminals:

Start MCP Server:
```
cd mcp_standard/mcp_server
npm start
```
Start MCP Client:
```
cd mcp_standard/mcp_client
npm start
```
Start MCP Host (Interactive CLI):
```
cd mcp_standard/mcp_host
npm start
```

Testing the Implementation

Once all components are running, you can interact with the system through the Host CLI:

👤 Your question: list all databases
🤖 Processing...

📋 Response:
============================================================
I found 3 databases in your MongoDB instance:

1. **admin** - System database (320 KB)
2. **config** - Configuration database (192 KB)  
3. **local** - Local database (256 KB)

All databases are currently active and not empty.
============================================================

Verifying MCP Compliance

This implementation follows the MCP standard by:

Using JSON-RPC 2.0 protocol for all communications
Implementing required methods: initialize, tools/list, tools/call
Following standard error codes (-32700 to -32603)
Supporting protocol version negotiation
Using proper request/response correlation with IDs
Implementing tool discovery with JSON Schema for parameters

API Examples

Initialize Request

{
  "jsonrpc": "2.0",
  "method": "initialize",
  "params": {
    "protocolVersion": "1.0",
    "clientInfo": {
      "name": "mcp-client",
      "version": "1.0.0"
    }
  },
  "id": "init_1"
}

Tool Call Request

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "list_collections",
    "arguments": {
      "database_name": "mydb"
    }
  },
  "id": "call_1"
}

Monitoring and Logging

JSON-RPC Message Logs

The implementation includes comprehensive JSON-RPC message logging. Each component logs all requests and responses in a formatted manner:

Log Files:

logs/mcp-server-jsonrpc.log - Server incoming/outgoing messages
logs/mcp-client-jsonrpc.log - Client incoming messages from host
logs/mcp-client-outgoing-jsonrpc.log - Client outgoing messages to server
logs/mcp-host-jsonrpc.log - Host outgoing messages to client

Log Format Example:

============================================================
Timestamp: 2024-01-20T10:30:45.123Z
Component: mcp-server
Direction: INCOMING
Type: REQUEST
============================================================
{
  "jsonrpc": "2.0",
  "method": "tools/list",
  "params": {},
  "id": "req_1234567890_1"
}
============================================================

============================================================
Timestamp: 2024-01-20T10:30:45.125Z
Component: mcp-server
Direction: OUTGOING
Type: RESPONSE
============================================================
{
  "jsonrpc": "2.0",
  "result": {
    "tools": [
      {
        "name": "list_databases",
        "description": "List all databases in MongoDB instance",
        "inputSchema": {
          "type": "object",
          "properties": {},
          "required": []
        }
      }
    ]
  },
  "id": "req_1234567890_1"
}
============================================================

Viewing Logs

Use the included log viewer for real-time monitoring:

cd mcp_standard
node view-logs.js

This provides:

Real-time log tailing
Color-coded output
Combined view of all components
Log clearing functionality

Standard Log Files

Each component also maintains standard operation logs:

mcp-server-standard.log
mcp-client-standard.log
mcp-host-standard.log