Spector 1.0.1

Spector

A lightweight network and dependency inspector for ASP.NET Core applications. Spector captures HTTP traces (incoming and outgoing requests) and provides a real-time web UI for monitoring and debugging.

Features

• 🔍 HTTP Request Tracing - Automatically captures incoming and outgoing HTTP requests
• 📊 Real-time Monitoring - Live updates via Server-Sent Events (SSE)
• 🎨 Embedded Web UI - Beautiful, responsive interface for viewing traces
• 🔗 Dependency Tracking - Visualize request/response chains and dependencies
• 📦 Zero Configuration - Works out of the box with sensible defaults
• 🚀 Lightweight - Minimal performance overhead

Installation

Install the Spector NuGet package:

dotnet add package Spector

Or via Package Manager Console:

Install-Package Spector

Quick Start

1. Add Spector to your services

In your Program.cs or Startup.cs:

using Spector;

var builder = WebApplication.CreateBuilder(args);

// Add Spector services
builder.Services.AddSpector();

// ... other service registrations

var app = builder.Build();

// Use Spector middleware
app.UseSpector();

// ... other middleware

app.Run();

2. Access the UI

Run your application and navigate to:

http://localhost:<your-port>/local-insights

You'll see a real-time dashboard showing all HTTP traces captured by your application.

Configuration

Spector works with zero configuration, but you can customize it if needed:

builder.Services.AddSpector();

Available Options

The SpectorOptions class provides the following configuration:

• UiPath - Custom path for the UI (default: /local-insights)
• SseEndpoint - Custom SSE endpoint path (default: /local-insights/events)
• ActivitySourceName - Activity source name for tracing (default: Spector)
• InMemoryMaxTraces - Maximum number of traces to keep in memory (default: 100)

To customize options, modify the SpectorOptions instance after registration:

builder.Services.AddSpector();
builder.Services.Configure<SpectorOptions>(options =>
{
    options.UiPath = "/my-custom-path";
    options.InMemoryMaxTraces = 200;
});

How It Works

Spector uses ASP.NET Core's built-in diagnostics features:

1. Activity Tracing - Leverages System.Diagnostics.Activity for distributed tracing
2. Middleware - Captures incoming HTTP requests via middleware
3. HTTP Handler - Intercepts outgoing HTTP calls via IHttpMessageHandlerBuilderFilter
4. In-Memory Storage - Stores recent traces in memory for quick access
5. SSE Streaming - Pushes updates to the UI in real-time

What Gets Captured

For each HTTP request/response, Spector captures:

• Request Details

  • HTTP method (GET, POST, etc.)
  • Full URL
  • Headers
  • Request body (when available)
  • Timestamp

• Response Details

  • Status code
  • Headers
  • Response body (when available)
  • Duration

• Trace Context

  • Trace ID
  • Span ID
  • Parent-child relationships

Use Cases

• Development - Debug API calls and inspect request/response data
• Testing - Verify HTTP interactions during integration tests
• Troubleshooting - Identify slow dependencies or failing requests
• Learning - Understand how your application communicates with external services

Requirements

• .NET 8.0 or later
• ASP.NET Core application

License

MIT License - see LICENSE file for details

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

Support

For issues, questions, or feature requests, please open an issue on GitHub.