Regarding on timer!

izmo

21y2.3k

my program contains a timer that runs after a button is pressed to perform certain action. the situation is as following: By default the timer is set to False. After OK button is pressed, the timer is set to True (starts to run). I have use 'elapsed' to take the elapsed time as second to compare against value inside Session["Duration"] that i have converted into integer value. If elapsed's second is equal to value of Session["Duration"] then the status set to Invalid which will be saved into database (action is performed) and the timer is stopped. But when i run the program...the timer never runs......i feel that the method i use below is not correct...what i want to do is that a timer can run the following code while my program can carry out other actions at the same time. but now my timer seems not working....any comments or ways of doing this??....and what to do in order to implement it as a backgroud thread for the following......thanks.....it's urgent! ... private DateTime lastTime; private void CmdOK_Click(object sender, System.EventArgs e) { lastTime = DateTime.Parse(Session["Time"].ToString()); Session["Duration"] = txtDuration.Text; tmrMoney.Enabled = true; } ... private void tmrMoney_Elapsed(object sender, System.Timers.ElapsedEventArgs e) { DateTime nowTime = DateTime.Now; TimeSpan elapsed = nowTime - lastTime; string meter = TxtMeter.Text; if (elapsed.Seconds = int.Parse(Session["Duration"].ToString())) { SqlCommand myCommand = new SqlCommand("UPDATE PaymentRecord SET Status = 'Invalid' WHERE Meter_Number = '" + meter + "'", myConnection); myConnection.Open(); myCommand.ExecuteNonQuery(); tmrMoney.Enabled = false; } lastTime = nowTime; } ... The timer interval is set to 1000 and tmrMoney_Elapsed is set to Elapsed event...I just really cannot make the timer work..so hope you guys can help...THANX...

You didn't mention this, but I'm assuming that this is a web application and not a web service. The problem you're running into is that running a background thread for a web application is a challenging proposition. In your particular situation, I suspect that the tmrMoney object is actually destroyed before the timer interval goes off. Figure that the following occur 1. A request comes in 2. A thread to process the request is created/retrieved from a pool 3. The cmdOK_Click method is executed 4. The response is built and returned to the client 5. All of the objects used to build the response are destroyed 6. The thread is returned to the pool/destroyed So before tmrMoney has an opportunity to fire, it is destroyed. If you're looking for a model to do this type of processing, you might want to look at the Caching Application Block released by the Patterns and Practices group at Microsoft. It launches a background thread when the web application is first started. That thread is then responsible for keeping track of the items that are stored in cache and when they get destroyed. Because the thread runs in the background *and is not associated with a particular request*, it can 'wake up' at any time and do the necessary processing. In the context of what you're trying to do, the execution of the UPDATE statement is the equivalent of a cache item expiring. Hope this helps. Bruce Johnson [C# MVP] http://www.objectsharp.com/blogs/bruce

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Bruce Johnson21y ago
You didn't mention this, but I'm assuming that this is a web application and not a web service. The problem you're running into is that running a background thread for a web application is a challenging proposition. In your particular situation, I suspect that the tmrMoney object is actually destroyed before the timer interval goes off. Figure that the following occur 1. A request comes in 2. A thread to process the request is created/retrieved from a pool 3. The cmdOK_Click method is executed 4. The response is built and returned to the client 5. All of the objects used to build the response are destroyed 6. The thread is returned to the pool/destroyed So before tmrMoney has an opportunity to fire, it is destroyed. If you're looking for a model to do this type of processing, you might want to look at the Caching Application Block released by the Patterns and Practices group at Microsoft. It launches a background thread when the web application is first started. That thread is then responsible for keeping track of the items that are stored in cache and when they get destroyed. Because the thread runs in the background *and is not associated with a particular request*, it can 'wake up' at any time and do the necessary processing. In the context of what you're trying to do, the execution of the UPDATE statement is the equivalent of a cache item expiring. Hope this helps. Bruce Johnson [C# MVP] http://www.objectsharp.com/blogs/bruce
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