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Spidey is a flexible and extensible .NET library for crawling web content. It is designed for .NET Core applications and provides a modular architecture, allowing you to customize or extend any part of the crawling pipeline.

Features

  • Simple API for crawling websites
  • Highly configurable via the Options class
  • Dependency injection support (IoC/DI)
  • Easily replaceable subsystems (engine, parser, scheduler, etc.)
  • Callback-based result handling
  • NuGet package available

Quick Start

Install the NuGet package:

dotnet add package Spidey

Setting up the Library

Register Spidey in your app's service collection using the RegisterSpidey extension method:

using Microsoft.Extensions.DependencyInjection;
using Spidey;

var services = new ServiceCollection();
services.RegisterSpidey();

// Optionally, register your Options configuration
services.AddSingleton(new Options
{
    ItemFound = result => Console.WriteLine($"Found: {result.Url}"),
    Allow = new List<string> { "http://mywebsite", "http://mywebsite2" },
    FollowOnly = new List<string> { /* regex patterns */ },
    Ignore = new List<string> { /* regex patterns */ },
    StartLocations = new List<string> { "http://mywebsite", "http://mywebsite2" },
    UrlReplacements = new Dictionary<string, string> { /* { "old", "new" } */ },
    // Other options as needed
});

var provider = services.BuildServiceProvider();
var crawler = provider.GetRequiredService<Crawler>();

Alternatively, you can instantiate Crawler and Options directly without DI:

var options = new Options
{
    ItemFound = result => Console.WriteLine($"Found: {result.Url}"),
    // ...other options
};
var crawler = new Crawler(options);

Options Configuration

The Options class configures the crawler's behavior. Key properties include:

  • ItemFound (Action<ResultFile>): Callback invoked when a new page is discovered.
  • Allow (List<string>): Regex patterns for URLs allowed to be crawled.
  • FollowOnly (List<string>): Regex patterns for pages whose links should be followed.
  • Ignore (List<string>): Regex patterns for URLs to ignore.
  • StartLocations (List<string>): Initial URLs to start crawling from.
  • UrlReplacements (Dictionary<string, string>): URL replacements during crawling.
  • NetworkCredentials (NetworkCredential): Optional credentials for authentication.
  • UseDefaultCredentials (bool): Use default system credentials.
  • Proxy (IWebProxy): Optional proxy settings.

Example callback method:

void OnItemFound(ResultFile result)
{
    Console.WriteLine($"Discovered: {result.Url} (Status: {result.StatusCode})");
    // Additional processing...
}

Basic Usage

Once configured, start the crawl process:

crawler.StartCrawl();

The library will handle link discovery, content downloading, and result parsing. Your callback will be invoked for each discovered item.

Customization

Spidey is built with extensibility in mind. The system is divided into the following subsystems, each replaceable via DI:

  1. Content Parser (IContentParser) – Parses downloaded data into ResultFile objects.
  2. Engine (IEngine) – Handles HTTP requests and content downloading.
  3. Link Discoverer (ILinkDiscoverer) – Extracts links from content.
  4. Processor (IProcessor) – Processes parsed content (default: invokes your callback).
  5. Scheduler (IScheduler) – Manages work distribution.
  6. Pipeline (IPipeline) – Orchestrates the crawling process.

To customize, implement the relevant interface from Spidey.Engines.Interfaces and register your implementation in the service provider. Note that if you call RegisterSpidey(), the registration is handled for you automatically. If you instantiate Crawler directly, you must compose the pipeline manually.

FAQ

Q: Can I run the crawler on multiple nodes?

A: The default scheduler is single-node only. For distributed crawling, implement a custom scheduler (e.g., using a database or message queue) to coordinate work between instances.

Build Process

Requirements:

  • Visual Studio 2022

Clone the project and open the solution (Spidey.sln) in Visual Studio to build.

License

See LICENSE for details.

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