haliphax / dn6-redirector

Redirect middleware / API reference implementation

.NET 6 Redirector Middleware / RESTful API

This project is a proof of concept for both a Middleware component and an accompanying RESTful API. The API is responsible for providing a redirect map, while the Middleware is responsible for checking the current request URL against the redirect map and taking appropriate action.

The lock flow control is used for thread safety when reading from or assiging to the redirect map. A copy of the redirect map is available upon request by invoking the CachedRedirects() method of the IRedirectApiService singleton.

Barebones class documentation is available.

Run the demo

First, start the demo API service application:

dotnet run --project DemoAPI

Next, start the demo web site:

dotnet run --project DemoSite

Finally, visit the demonstration endpoint at http://localhost:5000.

Some quick test URLs:

• http://localhost:5000/campaignA (to demonstrate absolute redirection)
• http://localhost:5000/CAMPAiGnB (to demonstrate URL normalization)
• http://localhost:5000/product-directory/hammer/sledge (to demonstrate relative redirection)

Configuration

The Middleware deals with two configuration values in appsettings.json:

• Todd.Redirector:ApiBaseUrl The base URL of the API web application
• Todd.Redirector:RefreshDelay The time (in milliseconds) between calls to refresh the redirect map from the API

The refresh delay may be ommitted, and will default to 10 seconds for demonstration purposes. The base URL of the API web application is required if you are using the IConfiguration constructor for the IRedirectApiService singleton. If you use the HttpClient constructor, it is assumed that the BaseAddress property of the client has already been configured.

{
	"Todd.Redirector": {
		"ApiBaseUrl": "http://localhost:5177/",
		"RefreshDelay": 15000
	}
}

Use in your own projects

For inclusion in your own projects, you must set up the API service:

using Todd.Redirector;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<IRedirectApiService>(
	new RedirectApiService(builder.Configuration));

If you want to use the HttpClient constructor for the IRedirectApiService singleton, you should set the BaseAddress property yourself:

using Todd.Redirector;

var client = new HttpClient();
client.BaseAddress = new Uri("http://some.host:1234");
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<IRedirectApiService>(
	new RedirectApiService(client));

Next, you must set up the Middleware:

var app = builder.Build();
app.UseMiddleware<RedirectorMiddleware>();

Disclaimers

This solution is presented for demonstration purposes only. There is an intentional intermittent failure chance of 20% for every API service call in order to exhibit fault tolerance.