Scheduled jobs in ASP.NET website without buying d

问题:

How can I perform various task (such as email alert/sending news letter) on a configured schedule time on a shared hosting server?

回答1:

Here's a Global.ascx.cs file I've used to do this sort of thing in the past, using cache expiry to trigger the scheduled task:

public class Global : HttpApplication
{
    private const string CACHE_ENTRY_KEY = "ServiceMimicCacheEntry";
    private const string CACHE_KEY = "ServiceMimicCache";

    private void Application_Start(object sender, EventArgs e)
    {
        Application[CACHE_KEY] = HttpContext.Current.Cache;
        RegisterCacheEntry();
    }

    private void RegisterCacheEntry()
    {
        Cache cache = (Cache)Application[CACHE_KEY];
        if (cache[CACHE_ENTRY_KEY] != null) return;
        cache.Add(CACHE_ENTRY_KEY, CACHE_ENTRY_KEY, null,
                  DateTime.MaxValue, TimeSpan.FromSeconds(120), CacheItemPriority.Normal,
                  new CacheItemRemovedCallback(CacheItemRemoved));
    }

    private void SpawnServiceActions()
    {
        ThreadStart threadStart = new ThreadStart(DoServiceActions);
        Thread thread = new Thread(threadStart);
        thread.Start();
    }

    private void DoServiceActions()
    {
        // do your scheduled stuff
    }

    private void CacheItemRemoved(string key, object value, CacheItemRemovedReason reason)
    {
        SpawnServiceActions();
        RegisterCacheEntry();
    }
}

At the moment, this fires off your actions every 2 minutes, but this is configurable in the code.

回答2:

Somone on here was doing this by creating threads in global.asax. Sounded like they were having success with it. I've never tested this approach myself.

This in my opinion would be a better option then overloading the cache expiration mechanism.

回答3:

You can use ATrigger scheduling service on a shared hosting without any problem. A .Net library is also available to create scheduled tasks without overhead.

Disclaimer: I was among the ATrigger team. It's a freeware and I have not any commercial purpose.