MCP E-commerce Demo

# SSE Connection Management Implementation ## 🚀 Overview This document outlines the robust SSE (Server-Sent Events) connection management implementation for the MCP Laravel server, including client disconnect detection, connection cleanup, and keepalive mechanisms. ## ✅ **Key Features Implemented** ### 1. **Multi-Level Forceful Connection Cleanup** - **Primary Detection**: `connection_aborted()` checks before/after operations - **Secondary Detection**: `connection_status()` verification - **Tertiary Detection**: Heartbeat write test for broken pipe detection - **Consecutive Failure Tracking**: Monitors failed ping attempts (max 3 failures) - **Automatic Resource Cleanup**: Forces buffer cleanup and connection termination - **FastCGI Support**: Uses `fastcgi_finish_request()` for proper cleanup ### 2. **Enhanced Keepalive Mechanism** - **Periodic Ping Messages**: Sends heartbeat every 15 seconds with failure tracking - **Connection Health Monitoring**: Tracks uptime, ping counts, and memory usage - **Timeout Management**: Automatic disconnect after 1 hour maximum - **Wait-Period Monitoring**: Checks connection status during sleep intervals ### 3. **Robust Buffer Management** - **Immediate Output Flushing**: Forces buffer flush with error checking - **Stream Writing**: Uses `fwrite()` with error detection instead of `echo` - **Buffer Cleanup**: Explicit output buffer management on disconnect - **Nginx Compatibility**: Disables proxy buffering with enhanced headers ### 4. **Comprehensive Error Handling** - **Graceful Error Recovery**: Multi-level exception handling in stream context - **Connection Validation**: Pre and post-operation connection checks - **Error Reporting**: Structured error messages via SSE with fallback logging - **Resource Protection**: Memory and execution time monitoring --- ## 🔧 **Technical Implementation** ### **MCPSSEController Improvements** ```php // Enhanced features implemented: 1. Multi-Level Connection Detection: - connection_aborted() - Primary disconnect detection - connection_status() - Secondary state verification - Heartbeat write test - Tertiary broken pipe detection - Continuous monitoring during wait periods 2. Forceful Disconnect Handling: - Consecutive failure tracking (max 3 failures) - Resource cleanup with buffer management - FastCGI termination support - Error-resistant cleanup procedures 3. Robust Message Delivery: - fwrite() with error checking vs echo - Pre/post operation connection validation - Graceful degradation on send failures - Structured error responses 4. Enhanced Connection Lifecycle: - Setup with buffer optimization - Maintenance with failure monitoring - Cleanup with forced termination - Logging at each lifecycle stage ``` ### **Buffer and Output Management** ```php // Enhanced optimizations implemented: - set_time_limit(0): Unlimited execution time - ini_set('memory_limit', '512M'): Increased memory for robust handling - ignore_user_abort(false): Enable manual disconnect detection - ob_implicit_flush(true): Automatic buffer flushing - fwrite() error checking: Robust stream writing - fastcgi_finish_request(): Proper FastCGI cleanup - X-Accel-Buffering: no: Disable proxy buffering - Transfer-Encoding: chunked: Efficient streaming ``` --- ## 📋 **Connection Lifecycle** ### **1. Connection Establishment** ``` Client → POST /mcp/sse → Server ├── Generate unique connection ID ├── Set appropriate headers ├── Process initial request (if any) ├── Send welcome message └── Start keepalive loop ``` ### **2. Active Connection** ``` Every 15 seconds: ├── Check connection_aborted() ├── Send ping message ├── Flush output buffers ├── Validate connection state └── Sleep until next ping ``` ### **3. Connection Termination & Forceful Cleanup** ``` Triggered by: ├── Client disconnect (connection_aborted()) ├── Connection status abnormal ├── Consecutive ping failures (3 max) ├── Connection timeout (1 hour) ├── Server error/exception └── Manual disconnect Cleanup Process: ├── Attempt to send close message ├── Clean all output buffers ├── FastCGI request termination ├── Log connection closure ├── Release all resources └── Exit stream gracefully Forceful Closure: ├── Multiple connection checks ├── Error-resistant cleanup ├── Resource cleanup guarantee └── Memory leak prevention ``` --- ## 🧪 **Testing** ### **Server-Side Forceful Closure Test** ```bash cd /path/to/mcp_demo php test-sse-forceful-closure.php ``` **Tests Include:** - Normal disconnection (SIGTERM) - Abrupt disconnection (SIGKILL) - Connection timeout simulation - Multiple concurrent connections - Resource cleanup verification ### **Client-Side Test** 1. Start Laravel server: `php artisan serve` 2. Open browser: `http://localhost:8000/sse-test.html` 3. Test connection, ping, tools, and disconnect functionality ### **Manual cURL Test** ```bash curl -N -H "Accept: text/event-stream" \ -H "Content-Type: application/json" \ -d '{"jsonrpc":"2.0","method":"ping","params":{},"id":"test"}' \ http://localhost:8000/mcp/sse ``` --- ## 📊 **Monitoring and Logging** ### **Connection Events Logged** - ✅ Connection establishment with client details - ✅ Multi-level disconnect detection - ✅ Consecutive ping failure tracking - ✅ Connection timeout events - ✅ Error conditions and recovery attempts - ✅ Forced closure procedures - ✅ Resource cleanup verification ### **Enhanced Log Examples** ``` [INFO] SSE Connection establishing {"connection_id":"mcp_sse_66f8a1b2c3d4e","client_ip":"127.0.0.1","user_agent":"..."} [DEBUG] Connection aborted detected {"connection_id":"mcp_sse_66f8a1b2c3d4e"} [WARNING] Ping failed {"connection_id":"mcp_sse_66f8a1b2c3d4e","consecutive_failures":2} [INFO] Max consecutive failures reached, closing connection {"connection_id":"mcp_sse_66f8a1b2c3d4e","failures":3} [INFO] Forcing connection closure {"connection_id":"mcp_sse_66f8a1b2c3d4e"} [INFO] Connection forcefully closed {"connection_id":"mcp_sse_66f8a1b2c3d4e"} ``` --- ## 🔄 **SSE Message Format** ### **Standard Messages** ```javascript // Welcome Message event: welcome data: {"jsonrpc":"2.0","result":{"status":"connected","connection_id":"..."},"id":"welcome"} // Ping/Keepalive event: ping data: {"event":"ping","data":{"timestamp":1234567890,"ping_count":42,"uptime":630}} // Response event: response data: {"jsonrpc":"2.0","result":{...},"id":"request-123"} // Error event: error data: {"jsonrpc":"2.0","error":{"code":-32603,"message":"..."},"id":"request-123"} ``` --- ## 🌐 **Client Integration** ### **JavaScript Client Example** ```javascript // Enhanced EventSource handling fetch('/mcp/sse', { method: 'POST', headers: { 'Content-Type': 'application/json', 'Accept': 'text/event-stream' }, body: JSON.stringify(mcpRequest) }).then(response => response.body) .then(body => { const reader = body.getReader(); // Handle streaming response with disconnect detection }); ``` ### **n8n Integration** - ✅ Compatible with n8n MCP client expectations - ✅ Proper SSE event format for parsing - ✅ Reliable connection management for long-running workflows --- ## 🚀 **Performance Optimizations** ### **Memory Management** - 256MB memory limit for connections - Buffer flushing to prevent memory buildup - Resource cleanup on disconnect ### **Network Efficiency** - 15-second ping interval (balance between responsiveness and overhead) - Structured ping data (avoids unnecessary parsing) - Immediate buffer flushing for low latency ### **Scalability Considerations** - Unique connection tracking - Configurable timeout limits - Graceful resource management --- ## ✅ **Production Readiness** ### **Features Implemented** - ✅ **Multi-Level Client Disconnect Detection**: connection_aborted() + connection_status() + heartbeat checks - ✅ **Forceful Resource Cleanup**: Guaranteed cleanup with error-resistant procedures - ✅ **Connection Monitoring**: Comprehensive logging and failure tracking - ✅ **Enhanced Keepalive System**: Reliable ping/pong with failure detection - ✅ **Robust Error Handling**: Graceful error recovery and structured reporting - ✅ **Timeout Management**: Configurable connection limits with forced cleanup - ✅ **Buffer Management**: Optimized for real-time streaming with fwrite() error checking - ✅ **Cross-Platform Support**: Works with various SSE clients and FastCGI environments ### **Security Considerations** - Connection timeout prevents resource exhaustion - Proper header validation - Memory limits prevent DoS attacks - Connection tracking for monitoring --- ## 🎯 **Summary** The enhanced SSE implementation provides: 1. **Robust Connection Management**: Multi-level disconnect detection and forceful cleanup 2. **Real-time Communication**: Low-latency message delivery with failure-resistant keepalive 3. **Production Stability**: Enhanced resource management and error-resistant cleanup 4. **Monitoring Capabilities**: Comprehensive logging and connection lifecycle tracking 5. **Client Compatibility**: Works with browsers, n8n, and custom clients with improved reliability **The SSE endpoint now provides enterprise-grade forceful connection management with guaranteed resource cleanup!** 🚀 ### **Endpoints Available** - **SSE Stream**: `POST /mcp/sse` - Main SSE endpoint with enhanced connection handling - **Test Page**: `GET /sse-test.html` - Interactive testing interface - **Server Info**: `GET /mcp/stdio` - MCP server capabilities and endpoints All MCP tools continue to work seamlessly with the improved connection reliability!