LogSystem.Client 2.4.0

.NET SDK for LogSystem

Enterprise-grade logging SDK for .NET Framework 4.7.2+, .NET Core 2.0+, and .NET 6+, with file-based logging, distributed tracing, and seamless integration with ILogger and Log4Net.

🌟 Features

• ✅ File-Based Logging - Synchronous file writes with thread safety (optimized for .NET Framework)
• ✅ Logger API - Node.js-style convenience methods (Debug/Info/Warn/Error/Fatal)
• ✅ Distributed Tracing - Built-in trace_id, span_id auto-generation
• ✅ ILogger Integration - Seamless Microsoft.Extensions.Logging support
• ✅ Log4Net Integration - Custom appender for existing Log4Net applications
• ✅ Multi-Target - Supports .NET Framework 4.7.2+, .NET Core 2.0+, .NET 6+, .NET 8+
• ✅ Auto-Enrich - Automatic @timestamp, service, host, trace fields injection
• ✅ Exception Handling - Automatic stack trace extraction
• ✅ Vector Compatible - Works with Vector agent for log collection

📦 Installation

# Core client library
dotnet add package LogSystem.Client

# Log4Net integration (optional)
dotnet add package LogSystem.Log4Net

📚 Examples

• Console Application: See FormatExample/ for basic usage and Format methods
• ASP.NET Core Web API: See WebFormatExample/ for REST API integration with dependency injection

Quick test:

# Test console example
cd sdks/dotnet/FormatExample
dotnet run

# Test web API example
cd sdks/dotnet/WebFormatExample
dotnet run
# Visit http://localhost:5289/swagger

🚀 Quick Start

Basic Usage (File-Based Logging)

using LogSystem.Client;

var logger = new LogClient(new LogClientOptions
{
    ApiKey = "your-api-key",
    Service = "my-service",
    LogDirectory = "C:\\logs\\myapp",  // Windows
    // LogDirectory = "/var/logs/myapp",  // Linux
    Logger = "MyApp.MainClass",  // Optional: adds logger field
    EnableTracing = true
});

// Use logger API methods
logger.Info("Application started", new Dictionary<string, object>
{
    ["version"] = "1.0.0",
    ["environment"] = "production"
});

logger.Debug("Configuration loaded", new Dictionary<string, object>
{
    ["config_file"] = "app.json"
});

logger.Warn("High memory usage", new Dictionary<string, object>
{
    ["memory_mb"] = 950,
    ["threshold_mb"] = 1024
});

// Error with exception
try {
    ProcessOrder();
} catch (Exception ex) {
    logger.Error("Order processing failed", ex, new Dictionary<string, object>
    {
        ["order_id"] = "12345"
    });
}

// Dispose to ensure all logs are written
logger.Dispose();

Logger API Methods

// Available log levels (matching Node.js SDK)
logger.Debug(message, properties);     // Detailed diagnostic info
logger.Info(message, properties);      // General informational messages
logger.Warn(message, properties);      // Warning messages
logger.Error(message, properties);     // Error messages
logger.Fatal(message, properties);     // Critical errors

// Exception handling (auto-extracts error message and stack trace)
logger.Error(message, exception, properties);
logger.Fatal(message, exception, properties);

// log4net-style Format methods
logger.DebugFormat(format, ...args);   // Debug with string.Format
logger.InfoFormat(format, ...args);    // Info with string.Format
logger.WarnFormat(format, ...args);    // Warn with string.Format
logger.ErrorFormat(format, ...args);   // Error with string.Format
logger.FatalFormat(format, ...args);   // Fatal with string.Format

Format Method Examples:

var logger = new LogClient(new LogClientOptions
{
    ApiKey = "your-api-key",
    Service = "order-service",
    LogDirectory = "C:\\logs",
    Logger = "OrderService"
});

// Like log4net's DebugFormat
logger.DebugFormat("CreateMtpData：companyOrderId={0},sellid={1},qty={2}", 
    companyOrderId, sellid, qty);

// InfoFormat with currency formatting
logger.InfoFormat("Order {0} created by user {1} with total amount {2:C}", 
    orderId, userId, 299.99m);

// WarnFormat with threshold checking
logger.WarnFormat("Product {0} stock is low: {1} units remaining (threshold: {2})", 
    productId, currentStock, threshold);

// ErrorFormat with error code
logger.ErrorFormat("Payment gateway {0} failed for order {1} with error code {2}", 
    gatewayName, orderId, errorCode);

Log Output Format

Each log entry is written as a single-line JSON:

{
  "@timestamp": "2025-12-06T00:58:35Z",
  "api_key": "your-api-key",
  "service": "my-service",
  "host": "DESKTOP-PC",
  "logger": "MyApp.MainClass",
  "trace_id": "trace_abc123...",
  "span_id": "span_def456...",
  "level": "INFO",
  "message": "Application started",
  "version": "1.0.0",
  "environment": "production"
}

ILogger Integration (ASP.NET Core)

// Program.cs (.NET 6+)
var builder = WebApplication.CreateBuilder(args);

builder.Logging.AddProvider(new LogSystemLoggerProvider(new LogClientOptions
{
    ApiKey = "your-api-key",
    Service = "my-api",
    LogDirectory = "C:\\logs\\myapi",
    Logger = "API"
}));

var app = builder.Build();

// In controller
public class OrderController : ControllerBase
{
    private readonly ILogger<OrderController> _logger;
    
    public OrderController(ILogger<OrderController> logger)
    {
        _logger = logger;
    }
    
    [HttpPost]
    public IActionResult CreateOrder([FromBody] OrderRequest request)
    {
        _logger.LogInformation("Order created: {OrderId} by {UserId}", 
            request.OrderId, request.UserId);
        return Ok();
    }
}

Log4Net Integration

<log4net>
  <appender name="LogSystemAppender" type="LogSystem.Log4Net.LogSystemAppender, LogSystem.Log4Net">
    <ApiKey value="your-api-key" />
    <ServiceName value="my-app" />
    <LogDirectory value="C:\logs\myapp" />
    <Logger value="Log4NetApp" />
    <BatchInterval value="5000" />
  </appender>
  
  <root>
    <level value="INFO" />
    <appender-ref ref="LogSystemAppender" />
  </root>
</log4net>

using log4net;

var logger = LogManager.GetLogger(typeof(Program));

logger.Info("Application started");
logger.Error("Something went wrong", new Exception("Test exception"));

🔍 Distributed Tracing

Generate Trace IDs

// Generate trace and span IDs
var traceId = LogClient.GenerateTraceId();  // trace_abc123...
var spanId = LogClient.GenerateSpanId();    // span_xyz789...

await client.SendAsync(new Dictionary<string, object>
{
    ["trace_id"] = traceId,
    ["span_id"] = spanId,
    ["level"] = "INFO",
    ["message"] = "Request started"
});

Extract Trace Context from HTTP Headers

// In ASP.NET Core middleware
public async Task InvokeAsync(HttpContext context)
{
    var headers = context.Request.Headers.ToDictionary(
        kvp => kvp.Key, 
        kvp => kvp.Value.ToString()
    );
    
    var (traceId, parentId) = LogClient.ExtractTraceContext(headers);
    var currentSpanId = LogClient.GenerateSpanId();
    
    // Store in HttpContext for use in controllers
    context.Items["trace_id"] = traceId ?? LogClient.GenerateTraceId();
    context.Items["span_id"] = currentSpanId;
    context.Items["parent_id"] = parentId;
    
    await _next(context);
}

Create Trace Headers for Downstream Calls

var traceId = context.Items["trace_id"].ToString();
var spanId = context.Items["span_id"].ToString();

var httpClient = new HttpClient();
var traceHeaders = LogClient.CreateTraceHeaders(traceId, spanId);

foreach (var header in traceHeaders)
{
    httpClient.DefaultRequestHeaders.Add(header.Key, header.Value);
}

var response = await httpClient.PostAsync("http://downstream-service/api", content);

Complete Microservice Example

// API Gateway
var rootTraceId = LogClient.GenerateTraceId();
var gatewaySpanId = LogClient.GenerateSpanId();

await logger.SendAsync(new Dictionary<string, object>
{
    ["trace_id"] = rootTraceId,
    ["span_id"] = gatewaySpanId,
    ["parent_id"] = null,  // root span
    ["level"] = "INFO",
    ["message"] = "Gateway received request"
});

// Call Order Service
var orderHeaders = LogClient.CreateTraceHeaders(rootTraceId, gatewaySpanId);
// ... add headers to HttpClient request

// Order Service receives request
var (orderTraceId, orderParentId) = LogClient.ExtractTraceContext(receivedHeaders);
var orderSpanId = LogClient.GenerateSpanId();

await logger.SendAsync(new Dictionary<string, object>
{
    ["trace_id"] = orderTraceId,      // inherited from Gateway
    ["span_id"] = orderSpanId,
    ["parent_id"] = orderParentId,    // gatewaySpanId
    ["level"] = "INFO",
    ["message"] = "Order service processing"
});

⚙️ Configuration Options

LogClientOptions

Environment Variables (appsettings.json)

{
  "LogSystem": {
    "ApiKey": "your-api-key",
    "Service": "order-service",
    "Endpoint": "http://localhost:8888",
    "BatchSize": 100,
    "BatchInterval": 5000
  }
}

// Load from configuration
var options = new LogClientOptions();
builder.Configuration.GetSection("LogSystem").Bind(options);

builder.Logging.AddProvider(new LogSystemLoggerProvider(options));

📊 API Reference

LogClient

Constructor

public LogClient(LogClientOptions options)

Methods

SendAsync(Dictionary<string, object> logData)

Send a log entry asynchronously. Returns immediately after queuing.

await client.SendAsync(new Dictionary<string, object>
{
    ["level"] = "INFO",
    ["message"] = "User logged in",
    ["user_id"] = 12345
});

Send(Dictionary<string, object> logData)

Send a log entry synchronously (blocking). Use SendAsync for better performance.

client.Send(new Dictionary<string, object>
{
    ["level"] = "ERROR",
    ["message"] = "Critical error"
});

FlushAsync()

Flush queued logs immediately.

await client.FlushAsync();

Flush()

Flush synchronously (blocking).

client.Flush();

Static Methods

GenerateTraceId()

Generate a unique trace ID.

var traceId = LogClient.GenerateTraceId();  // "trace_abc123..."

GenerateSpanId()

Generate a unique span ID.

var spanId = LogClient.GenerateSpanId();  // "span_xyz789..."

ExtractTraceContext(IDictionary<string, string> headers)

Extract trace context from HTTP headers.

var (traceId, parentId) = LogClient.ExtractTraceContext(requestHeaders);

CreateTraceHeaders(string traceId, string spanId)

Create HTTP headers for downstream calls.

var headers = LogClient.CreateTraceHeaders(traceId, spanId);
// { "X-Trace-Id": "trace_...", "X-Span-Id": "span_..." }

LogSystemLoggerProvider

ILoggerProvider implementation for Microsoft.Extensions.Logging.

// With existing LogClient
public LogSystemLoggerProvider(LogClient client, bool disposeClient = false)

// With options
public LogSystemLoggerProvider(LogClientOptions options)

LogSystemAppender (Log4Net)

Log4Net appender with HTTP support.

Configuration Properties:

• ApiKey - API key (required)
• ServiceName - Service name (required)
• Endpoint - HTTP endpoint
• BatchSize - Batch size
• BatchInterval - Batch interval (ms)
• EnableBatch - Enable batching
• EnableTracing - Auto trace_id

🎯 Best Practices

1. Use Structured Logging

// ✅ Good: Structured fields
await client.SendAsync(new Dictionary<string, object>
{
    ["level"] = "INFO",
    ["message"] = "Order created",
    ["order_id"] = "ORD-12345",
    ["user_id"] = "user_789",
    ["amount"] = 99.99
});

// ❌ Bad: All in message
await client.SendAsync(new Dictionary<string, object>
{
    ["level"] = "INFO",
    ["message"] = "Order ORD-12345 created by user_789 for $99.99"
});

2. Propagate Trace Context

// Extract from incoming request
var (traceId, parentId) = LogClient.ExtractTraceContext(request.Headers);

// Use in current service
var currentSpanId = LogClient.GenerateSpanId();

// Pass to downstream services
var downstreamHeaders = LogClient.CreateTraceHeaders(
    traceId ?? LogClient.GenerateTraceId(), 
    currentSpanId
);

3. Use ILogger for ASP.NET Core

// Leverage ILogger's structured logging
_logger.LogInformation(
    "Order {OrderId} created by {UserId} for {Amount} {Currency}",
    "ORD-123", "user_789", 99.99, "USD"
);

// Automatically becomes:
// {
//   "message": "Order ORD-123 created by user_789 for 99.99 USD",
//   "OrderId": "ORD-123",
//   "UserId": "user_789",
//   "Amount": 99.99,
//   "Currency": "USD"
// }

4. Dispose Properly

// Use using statement
using var client = new LogClient(options);
await client.SendAsync(logData);
// Auto-flush on dispose

// Or manual flush
await client.FlushAsync();
client.Dispose();

5. Handle Errors Gracefully

try
{
    await RiskyOperation();
}
catch (Exception ex)
{
    await client.SendAsync(new Dictionary<string, object>
    {
        ["trace_id"] = traceId,
        ["span_id"] = spanId,
        ["level"] = "ERROR",
        ["message"] = "Operation failed",
        ["error_message"] = ex.Message,
        ["error_type"] = ex.GetType().Name,
        ["error_stack"] = ex.StackTrace
    });
}

📝 Examples

Run the included examples:

cd examples
dotnet run                              # All examples
dotnet run --project BasicExample       # Basic usage
dotnet run --project ILoggerExample     # ILogger integration
dotnet run --project TraceExample       # Distributed tracing

🔄 Migration from File-Based SDK (v1.x)

🧪 Testing

# Build all projects
dotnet build

# Run examples
cd examples
dotnet run

# Run with custom endpoint
$env:LOG_ENDPOINT="http://production-server:8888"
dotnet run

🤝 Compatibility

📄 License

MIT

🔗 Related

• Node.js SDK - JavaScript/TypeScript SDK
• Main Documentation - Platform overview

Version: 2.0.0
Last Updated: 2025-12-05
Status: ✅ Production Ready