Question

I am trying to trigger a url from a trigger in SQL Anywhere and not wait for the response.

In SQL Anywhere I have the following function:

CREATE FUNCTION "DBA"."sendCallback"( in @serverip text,in @url text ) 
returns char(255)
not deterministic
external name 'Callback.dll::Namspace.Callback.OpenUrlAsync(string, string) string' language CLR

And in C# I have the following program:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Net;
using System.ComponentModel;

namespace Namspace
{
    public static class Callback
    {

        public static string OpenUrlAsync(string server, string url)
        {
            try
            {
                Thread t1 = new System.Threading.Thread
                  (() =>
                  {
                      using (WebClient wc = new WebClient())
                      {
                          try
                          {
                              string result = wc.DownloadString(server + url);
                          }
                          catch (Exception ee)
                          {
                              Console.Error.WriteLine(ee.Message);
                          }
                      }
                  });
                t1.Start();

            }
            catch (Exception e)
            {
                Console.Error.WriteLine(e.Message);
            }

            return "done";
        }

    }
}

When I call this from ISQL it works perfectly, but when it is called from the trigger it loks like the tread gets aborted before it can make the call.

If I add t1.Join() after it is started I get the desired effect, but then it uses to much time to be called from a trigger.

Is it correct that the CLR gets “teared down” when the connection calling it is finished?

How can I make sure the thread finishes?

Answer 1

You could wrap the Call in a SQL Anywhere Event.

In your Table Trigger you can then use trigger event <MyEvent>

triggers are executed within its own connection. If you have a lot of transactions you can run out of connections or overload the server. Be carefull!