关于网页中实时更新的困惑

Question

在ASP.NET Web API中实现实时更新功能时遇到了一些困难。基本上，我网页的主页从API提取数据，该API是我主页的url扩展名。因此，例如，mywebpage.com是从mywebpage.com/api/data中提取的。我现在才意识到，这些数据仅在加载网页或刷新后才加载，因此我将数据从API提取到客户端的频率也无关紧要，因为API仅在初始加载时刷新数据或刷新。我相信轮询此API并异步检查更改会很容易，但是如果此API不是最新的，那甚至都没有关系。如何做到这一点，以便使该API保持最新状态，并可以从客户端中提取最新数据？该API从我的SQL数据库获取数据。

这是到目前为止我要从SQL获取数据的代码...我的最终希望是，有一种方法可以在OnChange事件触发时（也称为RefreshPage方法）刷新API中的数据。 ...

public List<TestStation> GetAllStations(string serverName)
    {
        List<TestStation> result = new List<TestStation>();

        SqlDependency.Start("Data Source="
            + serverName + ";"
            + "Initial Catalog=...;"
            + "User Id=...;Password=...;");


        using (SqlConnection connect = new SqlConnection("Data Source="
            + serverName + ";"
            + "Initial Catalog=...;"
            + "User Id=...;Password=...;"))
        {
            connect.Open();


            //create SqlQuery to receive all station information
            SqlCommand command = connect.CreateCommand();
            string query = " SELECT * "
                + " FROM db_owner.Stations"
                + " ORDER BY StationName ASC;";
            command.CommandText = query;
            command.CommandTimeout = TIMEOUT_HEARTBEAT;






            //need to use a second query for checking status with SqlDependency because SqlDependency does not allow queries with "Select * "
            SqlCommand statusCommand = connect.CreateCommand();
            string statusQuery = " SELECT PcName, TimeUtc, UtcOffset,"
               + " SchedulerVersion, StatusCode, StatusMessage "
               + " FROM db_owner.Heartbeat"
               + " WHERE PcName = @PCNAME"
               // + " AND SchedulerVersion NOT LIKE 'DEV%' "
               + " ORDER BY TimeUtc DESC ;";
            statusCommand.CommandText = statusQuery;
            statusCommand.CommandTimeout = TIMEOUT_INSTRUCTIONS;
            SqlDependency dependency =
            new SqlDependency(statusCommand);
            dependency.OnChange += new OnChangeEventHandler(RefreshPage);



            SqlDataReader reader = command.ExecuteReader();

            while (reader.Read())
            {
                try
                {
                    string name, Os, NPI, lastRestart, DutId, Suite, IDN, DUT_FQDN, CPU, Location;
                    bool suspended;
                    //name = reader.GetString(0);
                    name = (string)reader["StationName"];
                    List<string> updateInfo = GetStationUpdate("sepweb.srs.is.keysight.com", "SAD_NIGHTLY", name);
                    DutId = updateInfo[1];
                    Suite = updateInfo[2];
                    IDN = updateInfo[4];
                    DUT_FQDN = updateInfo[3];
                    CPU = updateInfo[5];
                    Location = updateInfo[6];
                    Os = (string)reader["OS"];

                    // Get NPI from the Profile Table
                    NPI = GetStationNPI(name, serverName);
                    if (!reader.IsDBNull(3))
                    {
                        lastRestart = (string)reader["LastRestart"]; ;
                    }
                    else
                    {
                        lastRestart = "01/01/0001 1:00:00 AM";
                    }

                    suspended = (bool)reader["Suspended"];

                    // Get Status From the Heartbeat Table
                    string status = RunningStatus(name, serverName);

                    // Create a test station object and add it to the list
                    result.Add(new TestStation(name, Os, NPI, lastRestart, suspended, status, DutId, IDN, DUT_FQDN, CPU, Suite, Location));
                }
                catch
                {
                    continue;
                }
            }
        }

        return result;
    }


    void RefreshPage(object sender, SqlNotificationEventArgs e)
    {
        ;
    }

此外，我使用此代码的Web API控制器如下所示。

public class ValuesController : ApiController
{
    // GET api/values
    public List<TestStation> GetStations()
    {
        SQLQuery sqlQ = new SQLQuery();
        List<TestStation> stationList = sqlQ.GetAllStations("...website.com");
        return stationList;
    }