OwinSharedConfig.cs

public class StsMiddleware
{
	private readonly Func<IDictionary<string, object>, Task> _next;
	private readonly IStsConfig _config;

	public StsMiddleware(Func<IDictionary<string, object>, Task> next)
		: this(next, new AppConfigStsConfig())
	{}

	public StsMiddleware(Func<IDictionary<string, object>, Task> next, IStsConfig config = null)
	{
		if (next == null)
		{
			throw new ArgumentNullException("next");
		}
		_next = next;
		_config = config ?? new AppConfigStsConfig();
	}
	
	public async Task Invoke(IDictionary<string, object> environment)
	{
		// etc
		await _next(environment);
	}
}

public class StsAdminMiddleware
{
	private readonly Func<IDictionary<string, object>, Task> _next;
	private readonly IAdminConfig _config;

	public StsAdminMiddleware(Func<IDictionary<string, object>, Task> next)
		: this(next, new AppConfigAdminConfig())
	{}

	public StsAdminMiddleware(Func<IDictionary<string, object>, Task> next, IAdminConfig config = null)
	{
		if (next == null)
		{
			throw new ArgumentNullException("next");
		}
		_next = next;
		_config = config ?? new AppConfigStsAdminConfig();
	}
	
	public async Task Invoke(IDictionary<string, object> environment)
	{
		// etc
		await _next(environment);
	}
}

public static class AppBuilderExtensions
{
	public static IAppBuilder UseSts(this IAppBuilder appBuilder, IStsConfig config = null)
	{
		return builder.Use<StsMiddleware>(config);
	}
	
	public static IAppBuilder UseStsAdmin(this IAppBuilder appBuilder, IStsAdminConfig config = null)
	{
		return builder.Use<StsAdminMiddleware>(config);
	}
}

// Example usage
public class Startup
{
	public void Configuration(IAppBuilder app)
	{
		var config = new DatabaseConfig();
		app
			.Map("/sts", stsBranch => stsBranch.UseSts(config))
			.Map("/admin", adminBranch => adminBranch.UseStsadmin(config));
	}
	
	private class DatabaseConfig : IStsConfig, IStsAdminConfig
	{
		//....
	}
}