I have a requirement in my MVC app.
I had an export to excel functionality that is taking 3 mins of time (user clicks on a export button and waits on).
This export downloads an excel that has multiple worksheets after applying certain rules on the data.
These rules are datamanipulations plus applying colors on the cells belonging to certain columns.
Inorder to avoid the wait time, I was asked to develop a code with in the MVC app that can run like a scheduled job.
This job has to export the excel to a dedicated folder with in the network on the scheduled time (daily once).
Also i was asked to develop a web page within the app which has links to download these excels.
Quesions here (Any help would be appreciated) :
I have chosen Quartz.NET to implement this requirement. This is an open source (to my little knowledge) that can
provide the facility to schedule a job (class developed in .NET). Is it the right choice or would there be any implications in future?
Is it really needed to develop a job like code or any other way of coding can address this?
I'm not very familiar with Quartz.net, but I do know that trying to run background/scheduled tasks from within the same process as the MVC application can be problematic.
Ref 1: http://haacked.com/archive/2011/10/16/the-dangers-of-implementing-recurring-background-tasks-in-asp-net.aspx/
Ref 2: http://www.hanselman.com/blog/HowToRunBackgroundTasksInASPNET.aspx
Essentially, you can't guarantee that the process will complete correctly when running it due to how IIS handles app pools (which is where you MVC process runs: assuming hosting on IIS anyway).
You mention running a scheduled task within your MVC app. Again, this is incorrect. Why can't you just slap a console app project into the solution and drive the code from there, then put it on the server and use the Windows Task Scheduler?
In terms of background tasks, the "correct" way to do this is to send a command from your MVC app to some sort of message queue, which can then ensure that the command doesn't get dropped. I've used RabbitMQ in the past (a middleware message broker). Perhaps this is the aim of Quartz.net.
This setup typically involves another app (for me, usually a console app run on the server) that receives the command message from the message queue and runs in it's own process, entirely separate from MVC and thus the issues inherent with IIS AppPools and background tasks.
A lot of work, really... one would think it'd be easier, but that's the surefire way to do it and maintain the integrity of the task to be run.
Can we test a pipeline that has windows with triggers that depend on processing time? For instance a streaming pipeline with a global window and a trigger to fire on elementCountAtLeast 0 will have different outputs depending on when the data comes in, so can we simulate that in any way?
Even if not for automated tests, being able to try out different windowing strategies and see their affects would be very useful
Totally agree. We're in the process of rewriting the DirectPipelineRunner to support this. Stay tuned!
I have written a RabbitMQ consumer by implementing the MessageListener interface and setting up a SimpleMessageListenerContainer. Its working well when I test it manually. Now I would like to write an integration test that:
Creates a message
Pushes the message to my RabbitMQ server
Waits while the message is consumed by my MessageListener implementation
Test makes some asserts once everything is done
However, since my MessageListener is running in a separate thread, it makes unit testing difficult. Using a Thread.sleep in my test to wait for the MessageListener is unreliable, I need some kind of blocking approach.
Is setting up a response queue and using rabbitTemplate.convertSendAndReceive my only option? I wanted to avoid setting up response queues, since they won't be used in the real system.
Is there any way to accomplish this using only rabbitTemplate.convertAndSend and then somehow waiting for my MessageListener to receive the message and process it? Ideally, I would imagine something like this:
rabbitTemplate.convertAndSend("routing.key", testObject);
waitForListner() // Somehow wait for my MessageListener consume the message
assertTrue(...)
assertTrue(...)
I know I could just pass a message directly to my MessageListener without connecting to RabbitMQ at all, but I was hoping to test the whole system if it is possible to do so. I plan on falling back to that solution if there is no way to accomlish my goal in a reasonably clean way.
There are several approaches, the easiest being to wrap your listener and pass in a CountDownLatch which is counted down by the listener and the main test thread uses
assertTrue(latch.await(TimeUnit.SECONDS));
You can also pass back the actual message received so you can verify it is as expected.
Also see the integration test cases in the framework itself.
I am developing my first web application using ASP.Net MVC, and I am in a situation where I would like a background service to process status notifications outside of the application, not unlike the reputation/badge system on stackoverflow.
What is the best way to handle something like this? Is it even possible in a shared-hosting environment like Godaddy, which I am using.
I don't need to communicate with the background worker directly, since I will be adding notification records to a database table with a column set to an "unprocessed" state. Then the worker will just scan the table on a regular schedule and processes what is ready.
Thanks for your advice.
Have you tried with quartz.net? I think it may fit your needs.
also take a look at this Simulate a Windows Service using ASP.NET to run scheduled jobs article.
it explains a nice way to schedule operations with no outer dependence.
The idea is to use Cache timeout to control the schedule. I've implemented it successfully on a project which required regular temp file cleaning. This cleaning is a bit heavy so we move this clean operation in a scheduled job (using the asp.net cache) to avoid having to deploy scheduled task or custom program.
To answer whether GoDaddy will support a seperate service you need to ask them.
However there are a number of creative ways that you can "get around" this issue on shared hosting.
Have a secure page that's purpose is to execute your background work. You could have scheduled task on a machine under your control that calls to this web page at set intervals.
Use a variation of the Background Worker Thread answer from #safi. Your background worker thread could check to see if another is already processing and stop, so that only one instance is running at a time.
If only one background task is enough for you then use the WebBackgrounder
And this is the article with detailed explanation.
What are the cons and pros of windows services vs scheduled tasks for running a program repeatedly (e.g. every two minutes)?
Update:
Nearly four years after my original answer and this answer is very out of date. Since TopShelf came along Windows Services development got easy. Now you just need to figure out how to support failover...
Original Answer:
I'm really not a fan of Windows Scheduler. The user's password must be provided as #moodforall points out above, which is fun when someone changes that user's password.
The other major annoyance with Windows Scheduler is that it runs interactively and not as a background process. When 15 MS-DOS windows pop up every 20 minutes during an RDP session, you'll kick yourself that didn't install them as Windows Services instead.
Whatever you choose I certainly recommend you separate out your processing code into a different component from the console app or Windows Service. Then you have the choice, either to call the worker process from a console application and hook it into Windows Scheduler, or use a Windows Service.
You'll find that scheduling a Windows Service isn't fun. A fairly common scenario is that you have a long running process that you want to run periodically. But, if you are processing a queue, then you really don't want two instances of the same worker processing the same queue. So you need to manage the timer, to make sure if your long running process has run longer than the assigned timer interval, it doesn't kick off again until the existing process has finished.
After you have written all of that, you think, why didn't I just use Thread.Sleep? That allows me to let the current thread keep running until it has finished and then the pause interval kicks in, thread goes to sleep and kicks off again after the required time. Neat!
Then you then read all the advice on the internet with lots of experts telling you how it is really bad programming practice:
http://msmvps.com/blogs/peterritchie/archive/2007/04/26/thread-sleep-is-a-sign-of-a-poorly-designed-program.aspx
So you'll scratch your head and think to yourself, WTF, Undo Pending Checkouts -> Yes, I'm sure -> Undo all today's work..... damn, damn, damn....
However, I do like this pattern, even if everyone thinks it is crap:
OnStart method for the single-thread approach.
protected override void OnStart (string args) {
// Create worker thread; this will invoke the WorkerFunction
// when we start it.
// Since we use a separate worker thread, the main service
// thread will return quickly, telling Windows that service has started
ThreadStart st = new ThreadStart(WorkerFunction);
workerThread = new Thread(st);
// set flag to indicate worker thread is active
serviceStarted = true;
// start the thread
workerThread.Start();
}
The code instantiates a separate thread and attaches our worker
function to it. Then it starts the thread and lets the OnStart event
complete, so that Windows doesn't think the service is hung.
Worker method for the single-thread approach.
/// <summary>
/// This function will do all the work
/// Once it is done with its tasks, it will be suspended for some time;
/// it will continue to repeat this until the service is stopped
/// </summary>
private void WorkerFunction() {
// start an endless loop; loop will abort only when "serviceStarted"
// flag = false
while (serviceStarted) {
// do something
// exception handling omitted here for simplicity
EventLog.WriteEntry("Service working",
System.Diagnostics.EventLogEntryType.Information);
// yield
if (serviceStarted) {
Thread.Sleep(new TimeSpan(0, interval, 0));
}
}
// time to end the thread
Thread.CurrentThread.Abort();
}
OnStop method for the single-thread approach.
protected override void OnStop() {
// flag to tell the worker process to stop
serviceStarted = false;
// give it a little time to finish any pending work
workerThread.Join(new TimeSpan(0,2,0));
}
Source: http://tutorials.csharp-online.net/Creating_a_.NET_Windows_Service%E2%80%94Alternative_1%3a_Use_a_Separate_Thread (Dead Link)
I've been running lots of Windows Services like this for years and it works for me. I still haven't seen a recommended pattern that people agree on. Just do what works for you.
Some misinformation here. Windows Scheduler is perfectly capable of running tasks in the background without windows popping up and with no password required. Run it under the NT AUTHORITY\SYSTEM account. Use this schtasks switch:
/ru SYSTEM
But yes, for accessing network resources, the best practice is a service account with a separate non-expiring password policy.
EDIT
Depending on your OS and the requirements of the task itself, you may be able to use accounts less privileged than Localsystem with the /ru option.
From the fine manual,
/RU username
A value that specifies the user context under which the task runs.
For the system account, valid values are "", "NT AUTHORITY\SYSTEM", or "SYSTEM".
For Task Scheduler 2.0 tasks, "NT AUTHORITY\LOCALSERVICE", and
"NT AUTHORITY\NETWORKSERVICE" are also valid values.
Task Scheduler 2.0 is available from Vista and Server 2008.
In XP and Server 2003, system is the only option.
In .NET development, I normally start off by developing a Console Application, which will run will all logging output to the console window. However, this is only a Console Application when it is run with the command argument /console. When it is run without this parameter, it acts as a Windows Service, which will stay running on my own custom coded scheduled timer.
Windows Services, I my mind, are normally used to manage other applications, rather than be a long running application. OR .. they are continuously-running heavyweight applications like SQL Server, BizTalk, RPC Connections, IIS (even though IIS technically offloads work to other processes).
Personally, I favour scheduled tasks over Window Services for repititive maintenance tasks and applications such as file copying/synchronisations, bulk email sending, deletion or archiving of files, data correction (when other workarounds are not available).
For one project I have been involved in the development of 8 or 9 Windows Services, but these sit around in memory, idle, eating 20MB or more memory per instance. Scheduled tasks will do their business, and release the memory immediately.
What's the overhead of starting and quitting the app? Every two minutes is pretty often. A service would probably let the system run more smoothly than executing your application so frequently.
Both solutions can run the program when user isn't logged in, so no difference there. Writing a service is somewhat more involved than a regular desktop app, though - you may need a separate GUI client that will communicate with the service app via TCP/IP, named pipes, etc.
From a user's POV, I wonder which is easier to control. Both services and scheduled tasks are pretty much out of reach for most non-technical users, i.e. they won't even realize they exist and can be configured / stopped / rescheduled and so on.
The word 'serv'ice shares something in common with 'serv'er. It is expected to always be running, and 'serv'e. A task is a task.
Role play. If I'm another operating system, application, or device and I call a service, I expect it to be running and I expect a response. If I (os, app, dev) just need to execute an isolated task, then I will execute a task, but if I expect to communicate, possibly two way communication, I want a service. This has to do with the most effective way for two things to communicate, or a single thing that wants to execute a single task.
Then there's the scheduling aspect. If you want something to run at a specific time, schedule. If you don't know when you're going to need it, or need it "on the fly", service.
My response is more philosophical in nature because this is very similar to how humans interact and work with another. The more we understand the art of communication, and "entities" understand their role, the easier this decision becomes.
All philosophy aside, when you are "rapidly prototyping", as my IT Dept often does, you do whatever you have to in order to make ends meet. Once the prototyping and proof of concept stuff is out of the way, usually in the early planning and discovering, you have to decide what's more reliable for long term sustainability.
OK, so in conclusion, it's highly dependent on a lot of factors, but hopefully this has provided insight instead of confusion.
A Windows service doesn't need to have anyone logged in, and Windows has facilities for stopping, starting, and logging the service results.
A scheduled task doesn't require you to learn how to write a Windows service.
It's easier to set up and lock down windows services with the correct permissions.
Services are more "visible" meaning that everyone (ie: techs) knows where to look.
This is an old question but I will like to share what I have faced.
Recently I was given a requirement to capture the screenshot of a radar (from a Meteorological website) and save it in the server every 10 minutes.
This required me to use WebBrowser.
I usually make windows services so I decided to make this one service too but it would keep crashing.
This is what I saw in Event Viewer
Faulting module path: C:\Windows\system32\MSHTML.dll
Since the task was urgent and I had very less time to research and experiment, I decided to use a simple console application and triggered it as a task and it executed smoothly.
I really liked the article by Jon Galloway recommended in accepted answer by Mark Ransom.
Recently passwords on the servers were changed without acknowledging me and all the services failed to execute since they could not logon.
So ppl claiming in the article comments that this is a problem. I think windows services can face same problem (Pls. correct me if I am wrong, I am jus a newbie)
Also the thing mentioned, if using task scheduler windows pop up or the console window pops up.
I have never faced that. It may pop up but it is at least very instantaneous.
Why not provide both?
In the past I've put the 'core' bits in a library and wrapped a call to Whatever.GoGoGo() in both a service as well as a console app.
With something you're firing off every two minutes the odds are decent it's not doing much (e.g. just a "ping" type function). The wrappers shouldn't have to contain much more than a single method call and some logging.
Generally, the core message is and should be that the code itself must be executable from each and every "trigger/client". So it should not be rocket science to switch from one to the other approach.
In the past we used more or less always Windows Services but since also more and more of our customers switch to Azure step by step and the swap from a Console App (deployed as a Scheduled Task) to a WebJob in Azure is much easier than from a Windows Service, we focus on Scheduled Tasks for now. If we run into limitations, we just ramp up the Windows Service project and call the same logic from there (as long as customers are working OnPrem..) :)
BR,
y
Windows services want more patience until it's done.
It has a bit hard debug and install. It's faceless.
If you need a task which must be done in every second, minute or hour,
you should choice Windows Service.
Scheduled Task is quickly developed and has a face.
If you need a daily or weekly task, you can use Scheduled Task.