ClientApiPoC/ApiService/TunnelServer.cs

using Microsoft.AspNetCore.SignalR;
using ClientApiPoC.Shared.SignalR;
using ClientApiPoC.Shared.Models;

namespace ClientApiPoC.ApiService {
    public class TunnelServer : TunnelServerBase {
        public TunnelServer(IHubContext<TunnelHub> hubContext, ClientTracker clientTracker) : base(hubContext, clientTracker) { }

        public async Task<IEnumerable<ClientResultModel>> GetDataFromAllClientsAsync() {
            var timestampServer = DateTime.UtcNow;
            var results = new List<ClientResultModel>();
            var clients = this.GetAllClients();
            foreach (var client in clients) {
                var clientData = await client.Value.InvokeAsync<ClientDataModel>("GetClientData", timestampServer, CancellationToken.None);
                var result = new ClientResultModel() {
                    ClientId = client.Key,
                    ClientData = clientData
                };
                results.Add(result);
            }
            return results;
        }
    }
}