// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace Microsoft.AspNetCore.SignalR;
 
/// <summary>
/// A provider abstraction for configuring the "User ID" for a connection.
/// </summary>
/// <remarks><see cref="IUserIdProvider"/> is used by <see cref="IHubClients{T}.User(string)"/> to invoke connections associated with a user.</remarks>
public interface IUserIdProvider
{
    /// <summary>
    /// Gets the user ID for the specified connection.
    /// </summary>
    /// <param name="connection">The connection to get the user ID for.</param>
    /// <returns>The user ID for the specified connection.</returns>
    string? GetUserId(HubConnectionContext connection);
}