Related
I have a function that supposes to run every night at 12 AM and to do some job
usually it takes 2 hours...
I want to create a trigger that calls it.
so I created an Azure function app with time trigger that calls with HTTP request to my controller that calls my function.
the controller function I created just for test.
[HttpGet]
public async Task<bool> updateFromRegAdmin()
{
try
{
RegEditApi_Service.retrieveRegAdminApiCredentials();
return true;
}
catch (Exception e)
{
Logger.writeToLog(Logger.LOG_SEVERITY_TYPE.Error, "", "updateFromRegAdmin ", e.Message);
return false;
}
}
so as I said the function "retrieveRegAdminApiCredentials" runs 2 hours.
and the problem is the request comes to timeout after a few minutes...
so how can I create a request that just triggers the inner function and let it run in the background?
by the way, I can't create a trigger on the server without an HTTP request because my company has scaled servers on Azure(it will run my trigger multiple time and create DB duplicates).
my previous solution to that was...
public class JobScheduler
{
public static void Start()
{
IScheduler scheduler = StdSchedulerFactory.GetDefaultScheduler();
scheduler.Start();
IJobDetail job = JobBuilder.Create<GetExchangeRates>().Build();
ITrigger trigger = TriggerBuilder.Create()
.WithDailyTimeIntervalSchedule
(s =>
s.WithIntervalInHours(24)
.OnEveryDay()
.StartingDailyAt(TimeOfDay.HourAndMinuteOfDay(00, 00))
)
.Build();
scheduler.ScheduleJob(job, trigger);
}
}
public class GetExchangeRates : IJob
{
public void Execute(IJobExecutionContext context)
{
Random random = new Random();
int randomNumber = random.Next(100000, 900000);
Thread.Sleep(randomNumber);
RegEditApi_Service.retrieveRegAdminApiCredentials();
}
}
If I understand you correctly, what you have is an Azure Function Timer trigger, that sends an HTTP request to your server with "RegEditApi_Service.retrieveRegAdminApiCredentials()".
The problem is, your function times out. To solve this, you should have the HTTP endpoint behind "retrieveRegAdminApiCredentials()", return immediately on accepting the request.
If you need some return value from the server, you should have the server put a message on some queue ( like Azure Storage queue) and have another Azure Function that listens to this queue, and accepts the message.
If the result of the long operation is relatively small, you can just have the result in the message. Otherwise, you would need to perform some operation, but this operation should be much quicker, because you have already performed the long running operation, and kept the answer, so now you will just retrieve it, and possibly do some cleanup.
You can also look into Azure Durable Functions, it is intended for this use case, but is still in preview, and I'm not sure how much benefit it will give you :
https://learn.microsoft.com/en-us/azure/azure-functions/durable-functions-overview#pattern-3-async-http-apis
Looks like you need a dedicated component able to schedule and execute a queue of tasks. There are nice frameworks for that, but if you dislike those for whatever reason, then make sure you initiate/reuse idle thread and force long execution there. As such, your API will return something alike: 200, OK meaning that process has started successfuly.
Key idea: distinct your threads explicitly. That's actually quite challenging.
Azure functions by default run to a maximum of 15 minutes (maybe 5, too lazy to check the documentation right now :-) ).
If your function is on a Consumption Plan, you can't increase this time. You can do it if you host your function on a App Service plan.
I've been creating an Azure WebJob, it works aparently fine but I need to create a new function and I need test locally before upload to production site, I run on Debug the console program and this recognize all functions but I can't trigger any function.
Documentation say next trigger is every minute.... (https://github.com/Azure/azure-webjobs-sdk-extensions#timertrigger)
My code:
public static async void ProcessAugustEndowments([TimerTrigger("0 */1 * * * *", RunOnStartup = true)] TimerInfo timerInfo)
{
Console.WriteLine("Endowments process tried");
await endowmentNotification();
}
Output:
I run on Debug the console program and this recognize all functions but I can't trigger any function.
Based on your code, I tested it on my side and found that when my firstly debug the application, then I could get the following output:
But, when I restarted the application, I found that it would take some time for the function to be triggered.
Please make sure that you have installed the latest version packages of "Microsoft.Azure.WebJobs" and "Microsoft.Azure.WebJobs.Extensions". For more details, you could follow this tutorial.
And please try to reduce the time interval in your TimerTrigger and wait for a period when the job host has started, then try to find out whether the function could be triggered on your side. Here is my code sample, you could refer to it.
Program.cs
static void Main()
{
JobHostConfiguration config = new JobHostConfiguration();
// Add Triggers and Binders for Timer Trigger.
config.UseTimers();
JobHost host = new JobHost(config);
//host.RunAndBlock();
host.Start();
Console.WriteLine("[{0}] Job Host started!!!", DateTime.Now);
Console.ReadLine();
}
Function.cs
//Function triggered by a timespan schedule every 5 sec.
public static async void ProcessAugustEndowments([TimerTrigger("*/5 * * * * *", RunOnStartup = true)] TimerInfo timerInfo)
{
Console.WriteLine("Endowments process tried");
await endowmentNotification();
}
private static async Task endowmentNotification()
{
//sleep for 2 sec to simulate processing business logic
await Task.Delay(TimeSpan.FromSeconds(2));
}
Additionally, if the TimerTrigger could not meet your requirement, you could refer to this official tutorial to create a schedule WebJob, also you could refer to this blog.
If your functions are not triggered, I presume it is because you didn't configure your JobHost you use TimerTrigger:
var config = new JobHostConfiguration();
config.UseTimers();
How the JobHost works with Triggers :
When the JobHost starts, it discovers and indexes the functions with some *TriggerAttribute.
By Specifying the config.UseTimers(); you tell to the JobHost to index functions with TimerTriggerAttribute.
This is also valid for others types of triggers like ServiceBusTrigger that need config.UseServiceBus() to work
As a First step I created Windows Service project configured it properly and
On second Step I have added TopShelf Version 3.1.135.0 in my project If I run my service through (F5 Run) then it is loading Top-shelf Console and service is completed successfully.
However When I am running it to install and Start it from command prompt I am having below TimeOut Error.
Topshelf.Hosts.StartHost Error: 0 : The service failed to start., System.Service
Process.TimeoutException: Time out has expired and the operation has not been co
mpleted.
public class AppService
{
LoggingService loggingService = new LoggingService(typeof(AppService).Name);
public void Start()
{
loggingService.Info("SampleService is Started");
ExtractProcess.Start();
TransformProcess.Start();
}
public void Stop()
{
loggingService.Info("SampleService is Stopped");
}
}
-- Updated Code to fix this issue
public void Start()
{
loggingService.Info("MPS.GOA.ETLService is Started");
ThreadStart myThreadDelegate = new ThreadStart(StartService);
Thread myThread = new Thread(myThreadDelegate);
myThread.Start();
}
private void StartService()
{
timer.Elapsed += new System.Timers.ElapsedEventHandler(OnElapsedTime);
timer.Interval = 60000 * ServiceIntervalInMinutes; //1 minute 60000 milliseconds
timer.Enabled = true;
Process();
}
private void Process()
{
ExtractProcess.Start();
TransformProcess.Start();
}
Any Suggestions?
This error is happening because you are running the extract and process methods in the Start method of the service. This is OK in Visual Studio, but when you install the service and start it, the Service Control Manager waits for the Start method to return, and if it does not do so within a certain time (30 seconds by default) then it will return this error.
You have several options, all of which will allow the Start method to return immediately:
Invoke the extract and transform methods on a separate thread
Invoke the extract and transform methods asynchronously
Use a timer to start the extract and transform process
In case you (like me) is struggling to get the service to start - and all you've found so far is references to starting work in a separate thread (and you already did) this might be the solution right here..
My problem was that I had an external JSON config file being read from the project's directory path. What I needed was to get the assembly path, so that when the .NET application is published and installed with Topshelf - it looks for the config file at the right place.
string assemblyPath = Path.GetDirectoryName(typeof(MyConfigManagerClass).Assembly.Location);
var builder = new ConfigurationBuilder()
.SetBasePath(assemblyPath)
.AddJsonFile("config.json", optional: false);
myConfigurationObject = builder.Build();
Topshelf gave an error saying the service couldn't be started, but now I finally know why.
In my case it was neither of the above solutions that solved it, but actual permissions within the topshelf service, that required access to a file that resided in an external server.
TopShelf program running on test server
Log file located on Production server
Test server does not have access to external servers, for security
reasons.
So I changed the program to refer everything internally inside it's own server, and it worked fine.
I have following class that returns number of current Request per Second of IIS. I call RefreshCounters every minute in order to keep Requests per Second value refreshed (because it is average and if I keep it too long old value will influence result too much)... and when I need to display current RequestsPerSecond I call that property.
public class Counters
{
private static PerformanceCounter pcReqsPerSec;
private const string counterKey = "Requests_Sec";
public static object RequestsPerSecond
{
get
{
lock (counterKey)
{
if (pcReqsPerSec != null)
return pcReqsPerSec.NextValue().ToString("N2"); // EXCEPTION
else
return "0";
}
}
}
internal static string RefreshCounters()
{
lock (counterKey)
{
try
{
if (pcReqsPerSec != null)
{
pcReqsPerSec.Dispose();
pcReqsPerSec = null;
}
pcReqsPerSec = new PerformanceCounter("W3SVC_W3WP", "Requests / Sec", "_Total", true);
pcReqsPerSec.NextValue();
PerformanceCounter.CloseSharedResources();
return null;
}
catch (Exception ex)
{
return ex.ToString();
}
}
}
}
The problem is that following Exception is sometimes thrown:
System.InvalidOperationException: Category does not exist.
at System.Diagnostics.PerformanceCounterLib.GetCategorySample(String machine,\ String category)
at System.Diagnostics.PerformanceCounter.NextSample()
at System.Diagnostics.PerformanceCounter.NextValue()
at BidBop.Admin.PerfCounter.Counters.get_RequestsPerSecond() in [[[pcReqsPerSec.NextValue().ToString("N2");]]]
Am I not closing previous instances of PerformanceCounter properly? What am I doing wrong so that I end up with that exception sometimes?
EDIT:
And just for the record, I am hosting this class in IIS website (that is, of course, hosted in App Pool which has administrative privileges) and invoking methods from ASMX service. Site that uses Counter values (displays them) calls RefreshCounters every 1 minute and RequestsPerSecond every 5 seconds; RequestPerSecond are cached between calls.
I am calling RefreshCounters every 1 minute because values tend to become "stale" - too influenced by older values (that were actual 1 minute ago, for example).
Antenka has led you in a good direction here. You should not be disposing and re-creating the performance counter on every update/request for value. There is a cost for instantiating the performance counters and the first read can be inaccurate as indicated in the quote below. Also your lock() { ... } statements are very broad (they cover a lot of statements) and will be slow. Its better to have your locks as small as possible. I'm giving Antenka a voteup for the quality reference and good advice!
However, I think I can provide a better answer for you. I have a fair bit of experience with monitoring server performance and understand exactly what you need. One problem your code doesn't take into account is that whatever code is displaying your performance counter (.aspx, .asmx, console app, winform app, etc) could be requesting this statistic at any rate; it could be requested once every 10 seconds, maybe 5 times per second, you don't know and shouldn't care. So you need to separate the PerformanceCounter collection code from that does the monitoring from the code that actually reports the current Requests / Second value. And for performance reasons, I'm also going to show you how to setup the performance counter on first request and then keep it going until nobody has made any requests for 5 seconds, then close/dispose the PerformanceCounter properly.
public class RequestsPerSecondCollector
{
#region General Declaration
//Static Stuff for the polling timer
private static System.Threading.Timer pollingTimer;
private static int stateCounter = 0;
private static int lockTimerCounter = 0;
//Instance Stuff for our performance counter
private static System.Diagnostics.PerformanceCounter pcReqsPerSec;
private readonly static object threadLock = new object();
private static decimal CurrentRequestsPerSecondValue;
private static int LastRequestTicks;
#endregion
#region Singleton Implementation
/// <summary>
/// Static members are 'eagerly initialized', that is,
/// immediately when class is loaded for the first time.
/// .NET guarantees thread safety for static initialization.
/// </summary>
private static readonly RequestsPerSecondCollector _instance = new RequestsPerSecondCollector();
#endregion
#region Constructor/Finalizer
/// <summary>
/// Private constructor for static singleton instance construction, you won't be able to instantiate this class outside of itself.
/// </summary>
private RequestsPerSecondCollector()
{
LastRequestTicks = System.Environment.TickCount;
// Start things up by making the first request.
GetRequestsPerSecond();
}
#endregion
#region Getter for current requests per second measure
public static decimal GetRequestsPerSecond()
{
if (pollingTimer == null)
{
Console.WriteLine("Starting Poll Timer");
// Let's check the performance counter every 1 second, and don't do the first time until after 1 second.
pollingTimer = new System.Threading.Timer(OnTimerCallback, null, 1000, 1000);
// The first read from a performance counter is notoriously inaccurate, so
OnTimerCallback(null);
}
LastRequestTicks = System.Environment.TickCount;
lock (threadLock)
{
return CurrentRequestsPerSecondValue;
}
}
#endregion
#region Polling Timer
static void OnTimerCallback(object state)
{
if (System.Threading.Interlocked.CompareExchange(ref lockTimerCounter, 1, 0) == 0)
{
if (pcReqsPerSec == null)
pcReqsPerSec = new System.Diagnostics.PerformanceCounter("W3SVC_W3WP", "Requests / Sec", "_Total", true);
if (pcReqsPerSec != null)
{
try
{
lock (threadLock)
{
CurrentRequestsPerSecondValue = Convert.ToDecimal(pcReqsPerSec.NextValue().ToString("N2"));
}
}
catch (Exception) {
// We had problem, just get rid of the performance counter and we'll rebuild it next revision
if (pcReqsPerSec != null)
{
pcReqsPerSec.Close();
pcReqsPerSec.Dispose();
pcReqsPerSec = null;
}
}
}
stateCounter++;
//Check every 5 seconds or so if anybody is still monitoring the server PerformanceCounter, if not shut down our PerformanceCounter
if (stateCounter % 5 == 0)
{
if (System.Environment.TickCount - LastRequestTicks > 5000)
{
Console.WriteLine("Stopping Poll Timer");
pollingTimer.Dispose();
pollingTimer = null;
if (pcReqsPerSec != null)
{
pcReqsPerSec.Close();
pcReqsPerSec.Dispose();
pcReqsPerSec = null;
}
}
}
System.Threading.Interlocked.Add(ref lockTimerCounter, -1);
}
}
#endregion
}
Ok now for some explanation.
First you'll notice this class is designed to be a static singleton.
You can't load multiple copies of it, it has a private constructor
and and eagerly initialized internal instance of itself. This makes
sure you don't accidentally create multiple copies of the same
PerformanceCounter.
Next you'll notice in the private constructor (this will only run
once when the class is first accessed) we create both the
PerformanceCounter and a timer which will be used to poll the
PerformanceCounter.
The Timer's callback method will create the PerformanceCounter if
needed and get its next value is available. Also every 5 iterations
we're going to see how long its been since your last request for the
PerformanceCounter's value. If it's been more than 5 seconds, we'll
shutdown the polling timer as its unneeded at the moment. We can
always start it up again later if we need it again.
Now we have a static method called GetRequestsPerSecond() for you to
call which will return the current value of the RequestsPerSecond
PerformanceCounter.
The benefits of this implementation are that you only create the performance counter once and then keep using until you are finished with it. Its easy to use because you simple call RequestsPerSecondCollector.GetRequestsPerSecond() from wherever you need it (.aspx, .asmx, console app, winforms app, etc). There will always be only one PerformanceCounter and it will always be polled at exactly 1 times per second regardless of how quickly you call RequestsPerSecondCollector.GetRequestsPerSecond(). It will also automatically close and dispose of the PerformanceCounter if you haven't requested its value in more than 5 seconds. Of course you can adjust both the timer interval and the timeout milliseconds to suit your needs. You could poll faster and timeout in say 60 seconds instead of 5. I chose 5 seconds as it proves that it works very quickly while debugging in visual studio. Once you test it and know it works, you might want a longer timeout.
Hopefully this helps you not only better use PerformanceCounters, but also feel safe to reuse this class which is separate from whatever you want to display the statistics in. Reusable code is always a plus!
EDIT: As a follow up question, what if you want to performance some cleanup or babysitting task every 60 seconds while this performance counter is running? Well we already have the timer running every 1 second and a variable tracking our loop iterations called stateCounter which is incremented on each timer callback. So you could add in some code like this:
// Every 60 seconds I want to close/dispose my PerformanceCounter
if (stateCounter % 60 == 0)
{
if (pcReqsPerSec != null)
{
pcReqsPerSec.Close();
pcReqsPerSec.Dispose();
pcReqsPerSec = null;
}
}
I should point out that this performance counter in the example should not "go stale". I believe 'Request / Sec" should be an average and not a moving average statistic. But this sample just illustrates a way you could do any type of cleanup or "babysitting" of your PerformanceCounter on a regular time interval. In this case we are closing and disposing the performance counter which will cause it to be recreated on next timer callback. You could modify this for your use case and according the specific PerformanceCounter you are using. Most people reading this question/answer should not need to do this. Check the documentation for your desired PerformanceCounter to see if it is a continuous count, an average, a moving average, etc... and adjust your implementation appropriately.
I don't know, if this passes you .. I've read article PerformanceCounter.NextValue Method
And there was a comment:
// If the category does not exist, create the category and exit.
// Performance counters should not be created and immediately used.
// There is a latency time to enable the counters, they should be created
// prior to executing the application that uses the counters.
// Execute this sample a second time to use the category.
So, I have a question, which can lead to answer: isn't call to a RequestsPerSecond method happends too early?
Also, I would suggest you to to try check if the Category doesn't exists and log the info somewhere, so we can analyze it and determine which conditions we have and how often that happends.
I just solved this type of error or exception with:
Using,
new PerformanceCounter("Processor Information", "% Processor Time", "_Total");
Instead of,
new PerformanceCounter("Processor", "% Processor Time", "_Total");
I had an issue retrieving requests per second on IIS using code similar to the following
var pc = new PerformanceCounter();
pc.CategoryName = #"W3SVC_W3WP";
pc.InstanceName = #"_Total";
pc.CounterName = #"Requests / Sec";
Console.WriteLine(pc.NextValue());
This would sometimes throw InvalidOperationException and I was able to reproduce the exception by restarting IIS. If I run with a non warmed up IIS, e.g. after a laptop reboot or IIS restart, then I get this exception. Hit the website first, make any http request beforehand, and wait a second or two and I don't get the exception. This smells like the performance counters are cached,and when Idle they get dumped, and take a while to re-cache? (or similar).
Update1: Initially when I manually browse to the website and warm it up, it solves the problem. I've tried programmatically warming up the server with new WebClient().DownloadString(); Thread.Sleep() up to 3000ms and this has not worked? So my results of manually warming up server, might somehow be a false positive. I'm leaving my answer here, because it might be the cause, (i.e. manual warming up), and maybe someone else can elaborate further?
Update2: Ah, ok, here are some unit tests that summarises some learning from further experimenting I did yesterday. (There's not a lot on google on this subject btw.)
As far as I can reason, the following statements might be true; (and I submit the unit tests underneath as evidence.) I may have misinterpreted the results, so please double check ;-D
Create a performance counter and calling getValue before the category exists, e.g. querying an IIS counter, while IIS is cold and no process running, will throw InvalidOperation exception "category does not exist". (I assume this is true for all counters, and not just IIS.)
From within a Visual Studio unit test, once your counter throws an exception, if you subsequently warm up the server after the first exception, and create a new PerformanceCounter and query again, it will still throw an exception! (this one was a surprise, I assume this is because of some singleton action. My apologies I have not had enough time to decompile the sources to investigate further before posting this reply.)
In 2 above, if you mark the unit test with [STAThread] then I was able to create a new PerformanceCounter after one has failed. (This might have something to do with Performance counter possibly being singletons? Needs further testing.)
No pause was required for me before creating counter and using it, despite some warnings in MSDN same code documentation, other than the time it takes to create a performance counter itself before calling NextValue().In my case, to warm up the counter and bring the "category" into existance, was for me to fire one shot across the bow of IIS, i.e. make a single GET request, and viola, no longer get "InvalidOperationException", and this seems to be a reliable fix for me, for now. At least when querying IIS performance counters.
CreatingPerformanceCounterBeforeWarmingUpServerThrowsException
[Test, Ignore("Run manually AFTER restarting IIS with 'iisreset' at cmd prompt.")]
public void CreatingPerformanceCounterBeforeWarmingUpServerThrowsException()
{
Console.WriteLine("Given a webserver that is cold");
Console.WriteLine("When I create a performance counter and read next value");
using (var pc1 = new PerformanceCounter())
{
pc1.CategoryName = #"W3SVC_W3WP";
pc1.InstanceName = #"_Total";
pc1.CounterName = #"Requests / Sec";
Action action1 = () => pc1.NextValue();
Console.WriteLine("Then InvalidOperationException will be thrown");
action1.ShouldThrow<InvalidOperationException>();
}
}
[Test, Ignore("Run manually AFTER restarting IIS with 'iisreset' at cmd prompt.")]
public void CreatingPerformanceCounterAfterWarmingUpServerDoesNotThrowException()
{
Console.WriteLine("Given a webserver that has been Warmed up");
using (var client = new WebClient())
{
client.DownloadString("http://localhost:8082/small1.json");
}
Console.WriteLine("When I create a performance counter and read next value");
using (var pc2 = new PerformanceCounter())
{
pc2.CategoryName = #"W3SVC_W3WP";
pc2.InstanceName = #"_Total";
pc2.CounterName = #"Requests / Sec";
float? result = null;
Action action2 = () => result = pc2.NextValue();
Console.WriteLine("Then InvalidOperationException will not be thrown");
action2.ShouldNotThrow();
Console.WriteLine("And the counter value will be returned");
result.HasValue.Should().BeTrue();
}
}
Just out of curiousity, what do you have set for properties in Visual Studio? In VS go to Project Properties, Build, Platform target and change it to AnyCPU. I have seen it before where Performance Counters aren't always retrieved when it is set to x86, and changing it to AnyCPU could fix it.
I'm fairly new to C#, and recently built a small webapp using .NET 4.0. This app has 2 parts: one is designed to run permanently and will continuously fetch data from given resources on the web. The other one accesses that data upon request to analyze it. I'm struggling with the first part.
My initial approach was to set up a Timer object that would execute a fetch operation (whatever that operation is doesn't really matter here) every, say, 5 minutes. I would define that timer on Application_Start and let it live after that.
However, I recently realized that applications are created / destroyed based on user requests (from my observation they seem to be destroyed after some time of inactivity). As a consequence, my background activity will stop / resume out of my control where I would like it to run continuously, with absolutely no interruption.
So here comes my question: is that achievable in a webapp? Or do I absolutely need a separate Windows service for that kind of things?
Thanks in advance for your precious help!
Guillaume
While doing this on a web app is not ideal..it is achievable, given that the site is always up.
Here's a sample: I'm creating a Cache item in the global.asax with an expiration. When it expires, an event is fired. You can fetch your data or whatever in the OnRemove() event.
Then you can set a call to a page(preferably a very small one) that will trigger code in the Application_BeginRequest that will add back the Cache item with an expiration.
global.asax:
private const string VendorNotificationCacheKey = "VendorNotification";
private const int IntervalInMinutes = 60; //Expires after X minutes & runs tasks
protected void Application_Start(object sender, EventArgs e)
{
//Set value in cache with expiration time
CacheItemRemovedCallback callback = OnRemove;
Context.Cache.Add(VendorNotificationCacheKey, DateTime.Now, null, DateTime.Now.AddMinutes(IntervalInMinutes), TimeSpan.Zero,
CacheItemPriority.Normal, callback);
}
private void OnRemove(string key, object value, CacheItemRemovedReason reason)
{
SendVendorNotification();
//Need Access to HTTPContext so cache can be re-added, so let's call a page. Application_BeginRequest will re-add the cache.
var siteUrl = ConfigurationManager.AppSettings.Get("SiteUrl");
var client = new WebClient();
client.DownloadData(siteUrl + "default.aspx");
client.Dispose();
}
private void SendVendorNotification()
{
//Do Tasks here
}
protected void Application_BeginRequest(object sender, EventArgs e)
{
//Re-add if it doesn't exist
if (HttpContext.Current.Request.Url.ToString().ToLower().Contains("default.aspx") &&
HttpContext.Current.Cache[VendorNotificationCacheKey] == null)
{
//ReAdd
CacheItemRemovedCallback callback = OnRemove;
Context.Cache.Add(VendorNotificationCacheKey, DateTime.Now, null, DateTime.Now.AddMinutes(IntervalInMinutes), TimeSpan.Zero,
CacheItemPriority.Normal, callback);
}
}
This works well, if your scheduled task is quick.
If it's a long running process..you definitely need to keep it out of your web app.
As long as the 1st request has started the application...this will keep firing every 60 minutes even if it has no visitors on the site.
I suggest putting it in a windows service. You avoid all the hoops mentioned above, the big one being IIS restarts. A windows service also has the following benefits:
Can automatically start when the server starts. If you are running in IIS and your server reboots, you have to wait until a request is made to start your process.
Can place this data fetching process on another machine if needed
If you end up load-balancing your website on multiple servers, you could accidentally have multiple data fetching processes causing you problems
Easier to main the code separately (single responsibility principle). Easier to maintain the code if it's just doing what it needs to do and not also trying to fool IIS.
Create a static class with a constructor, creating a timer event.
However like Steve Sloka mentioned, IIS has a timeout that you will have to manipulate to keep the site going.
using System.Runtime.Remoting.Messaging;
public static class Variables
{
static Variables()
{
m_wClass = new WorkerClass();
// creates and registers an event timer
m_flushTimer = new System.Timers.Timer(1000);
m_flushTimer.Elapsed += new System.Timers.ElapsedEventHandler(OnFlushTimer);
m_flushTimer.Start();
}
private static void OnFlushTimer(object o, System.Timers.ElapsedEventArgs args)
{
// determine the frequency of your update
if (System.DateTime.Now - m_timer1LastUpdateTime > new System.TimeSpan(0,1,0))
{
// call your class to do the update
m_wClass.DoMyThing();
m_timer1LastUpdateTime = System.DateTime.Now;
}
}
private static readonly System.Timers.Timer m_flushTimer;
private static System.DateTime m_timer1LastUpdateTime = System.DateTime.MinValue;
private static readonly WorkerClass m_wClass;
}
public class WorkerClass
{
public delegate WorkerClass MyDelegate();
public void DoMyThing()
{
m_test = "Hi";
m_test2 = "Bye";
//create async call to do the work
MyDelegate myDel = new MyDelegate(Execute);
AsyncCallback cb = new AsyncCallback(CommandCallBack);
IAsyncResult ar = myDel.BeginInvoke(cb, null);
}
private WorkerClass Execute()
{
//do my stuff in an async call
m_test2 = "Later";
return this;
}
public void CommandCallBack(IAsyncResult ar)
{
// this is called when your task is complete
AsyncResult asyncResult = (AsyncResult)ar;
MyDelegate myDel = (MyDelegate)asyncResult.AsyncDelegate;
WorkerClass command = myDel.EndInvoke(ar);
// command is a reference to the original class that envoked the async call
// m_test will equal "Hi"
// m_test2 will equal "Later";
}
private string m_test;
private string m_test2;
}
I think you can can achieve it by using a BackgroundWorker, but i would rather suggest you to go for a service.
Your application context lives as long as your Worker Process in IIS is functioning. In IIS there's some default timeouts for when the worker process will recycle (e.g. Number of Idle mins (20), or regular intervals (1740).
That said, if you adjust those settings in IIS, you should be able to have the requests live, however, the other answers of using a Service would work as well, just a matter of how you want to implement.
I recently made a file upload functionality for uploading Access files to the database (not the best way but just a temporary fix to a longterm issue).
I solved it by creating a background thread that ran through the ProcessAccess function, and was deleted when completed.
Unless IIS has a setting in which it kills a thread after a set amount of time regardless of inactivity, you should be able to create a thread that calls a function that never ends. Don't use recursion because the amount of open functions will eventually blow up in you face, but just have a for(;;) loop 5,000,000 times so it'll keep busy :)
Application Initialization Module for IIS 7.5 does precisely this type of init work. More details on the module are available here Application Initialization Module