Let me explain the scenario and what I am trying to accomplish.
Scenario:
I have a web application that collects a date (ex 07/12/2011) and a time (ex 07:45PM) and store them into database (SQL).
What I am trying to do:
At 07:45PM on 07/12/2011, I want to call a web service to run another job.
I am thinking about building a windows service that runs every 15 minutes everyday, gathers all the "pending" requests (dates and times), queues them up, and executes the requests in that order.
Please feel free to provide any other approach for this.
In the past when I have done this I use the Windows Task Scheduler to run the exe that does what I want.
For what you are wanting to do a windows service seems like overkillm, I typically just create a basic console app that does what I need. With the Task Scheduler you can specify exactly when you want to run it and you are done.
Windows Services add a (sometimes) unnecessary level of complexity to a problem like this.
I would recommend starting with a simple console application and using Windows Scheduler to run it every x minutes.
If you decide to convert to a "real" service at a later time almost all of your code should be reusable.
You could evaluate the following solutions before writing out a windows service.
http://www.firedaemon.com/ - FireDeamon provides a free version for scheduling jobs.
http://quartznet.sourceforge.net/ - An open source scheduling library, good to go for if your windows service need to support more features.
If you are working on .NET Framework 4, this link should shed some light on this issue.
I've used Quartz.Net with some success. It's a bit more flexible than you've described. Scheduling a new task is as easy as:
public static void Schedule(DateTime when, string applicationId)
{
ISchedulerFactory factory = new StdSchedulerFactory();
IScheduler scheduler = factory.GetScheduler();
JobDetail jobDetail = new JobDetail("Realization Job", null, typeof(CustomTask));
jobDetail.JobDataMap["applicationId"] = applicationId;
Trigger trigger = new SimpleTrigger("Custom Task Trigger", DateTime.UtcNow, null, 0, TimeSpan.Zero);
scheduler.ScheduleJob(jobDetail, trigger);
}
Note that I have a wrapper around the JobScheduler that allows it to act as a Windows service. Creating this as a Windows service allows me to have more robust error handling and does not force me to rely on the OS like the Task Scheduler does.
I've used both Windows Task Scheduler and Windows Services in different web projects, both have their merits.
Personally, I prefer using scheduled tasks. Usually, I'll have a small generic tool calling a URL in the main web application. Sort of like a web service call. The output is appended to a log file.
The benefit of this setup is that if you deploy a new version of the web application, the service is updated as well.
I'd recommend a Windows Service only if you have to perform long-running tasks or tasks that require access to unsafe resources since these don't work well with web applications.
Then again, the same sort of tasks could also be performed from a command line tool.
In practice I've found that main problem with Windows Services is the fact they run indefinitely. In a perfect world that's not a problem. In the real world however, I've seen services leaking memory (yes, .NET based services). Over time these services will start to suck up more and more resources.
A scheduled task will start a new process for each invocation, limiting the amount of damage a leaky task can do.
Related
I've been building a web service to synchronize data between SalesForce and Zendesk at my company. In the process of doing so, I've built several optimizations to drastically reduce execution time, such as caching some of the larger datasets that are retrieved from each service.
However, this comes at a price. When caching the data, it can upwards to 3-5 minutes to download everything through SalesForce and Zendesk's APIs.
To combat this, I was thinking of having a background worker that automatically cached all the required data every day a midnight. However, I'm not sure what the best method of doing this would be.
Would it suffice to build a class that merely has a worker thread that checks every several minutes to see if it is after midnight, and activate it on launch from Global.asax. Or is there some sort of scheduler already in existence?
EDIT
There seems to be some division between using something like:
FluentScheduler or Quartz.net to house everything within my applications.
Versus using something like windows task scheduler and writing a secondary application to call a function of my application to do so. It seems that using a third party library would be more simple, but is there any inherent benefit to using the Windows Task Scheduler.
I think you want to add your data caching logic to a project of type "console application". You'll be able to deploy this to your server and run it as a scheduled task using windows "Task Scheduler". If you've not worked with this project type or scheduled tasks before there are stack overflow questions which should help here, here, and here. You can add command line parameters if you need and you should have a look at adding a mutex so that only one instance of your code will ever run at once.
add an endpoint that will know how do it and use the windows task scheduler to call that new caching endpoint.
I am creating a web application in which I need to allow the user to schedule the excecution of a task.
I have gone through the various threads for scheduling the task but all of them are using windows service that I am not aware of. Moreover I cannot install visual studio in the server systems due to budget constraints.
Is there a way to create a method that runs a scheduler in a background thread in the asp .net application.Any code sample will be of great help.
That's not the way to go. If you need a scheduled task you should create a console application and run it using the Windows task scheduler.
You could create an application that sends an email to the user with a link to the page where the task is supposed to be done.
One thing to understand is that ASP.NET is intended to service requests from the network.
Everything in it is geared towards that. So, yes, you can run background tasks, but there are a number of caveats and gotcha's.
For instance, IIS will shut down your ASP.NET application if it does not receive any requests for some period. Also, your Application may be restarted without warning, if it detects changes to the file system. So, running code will be aborted.
That's not to say you can't work around these, but it's really not the best fit for scheduled task execution.
Your best bet would be to store the details of the task in a database, and then using either a single always-running Windows Service (really not that difficult to do, there are plenty of examples), or a console application (as suggested) scheduled manually to run regularly, to execute these tasks.
You may find that a library such as Quartz.NET may be of help scheduling/running these tasks.
I'm new to the whole concept of ASP.NET, so please be patient with me. My requirement is to create a scheduling component that will do some tasks that are stored in a database. What's the most common way of implementing this. My idea is to store intervals as TimeSpan and somehow poll my database in very short intervals.
I would like to recommend to implement task executor as Windows Service.
Here are some approaches:
The service may periodically polls the database and perform the tasks.
Using MSMQ. It allows to use system-wide queues: one process (ASP.NET web application) can produce queue items, another one (the service) - consume them.
How to do asynchronous programming using ASP.NET, MSMQ and Windows Service, for long running processes.
For more advanced scheduling scenarios, Quartz.net is a very useful tool - http://quartznet.sourceforge.net/ - ported from Java (I think).
As others are pointing out, ASP.Net's lifecycle isn't well suited to regular scheduled tasks. However, I've seen several web apps and web app frameworks (e.g. DotNetNuke and YetAnotherForum, I think) which perform scheduled tasks by occasionally borrowing threadpool threads after web hits have been serviced. This is very useful in shared hosting models where you're normally restricted in what you can install on the server.
If you're looking at short intervals, you usually use a Timer class - there are several in the Framework e.g. System.Timers.Timer and System.Threading.Timer. You set the Interval as a number of milliseconds (using the TimeSpan static methods such as FromSeconds or FromMinutes for ease of reading)
Look at System.Timers.Timer vs System.Threading.Timer for a comparison of the two timers
I have a Windows Service that is meant to run a 2-minute job once a day. The remaining 23:58 of the day, it just sits around looking pretty.
My question relates firstly to the idle time: is it better to use a Timer.Tick, or a Thread.Sleep? Is there any difference between the resources either of these use?
Secondly, during that idle time, if someone shuts down the Windows Service, do I need to interrupt those idle threads for the program to shut down cleanly, or will the Shutdown handle it for me?
Thirdly, am I barking up the wrong tree by using a Windows Service? It would seem to make sense to put a record into the Windows Task Scheduler, but I couldn't find any way to do that using InstallShield, which is what we're using to deploy our product. Any better ideas?
If you start a background thread with ThreadPool.QueueUserWorkItem I think you could have a Thread.Sleep in there and when you shut the service down you would not have to do anything with it. I think Timer Tick would automatically do the thread creation for you when it ticks, so you would have to do even less if you used that (out of the two the timer tick would, I think match what you want to achieve better so would be the better choice).
This definately feels like something that would be better done by a scheduler like you say though. I don't know if you can do it directly within InstallShield but perhaps you could create a little console app that you run from the installer that based on a command line argument either talks to the windows task schedular API - http://msdn.microsoft.com/enus/library/windows/desktop/aa383614(v=vs.85).aspx to register itself or does the job you want to acheive (i.e -install - set it up on the schedular, no args do whatever it is you need to do once a day).
I think it is a C++ API so you could do a bit of p/invoke or, better, just have some managed C++ in a class libaray and reference it from a c# based console application.
FWIW, InstallShield doesn't have native capabilities to define scheduled tasks but it does support VBScript, C++ and InstallScript custom actions. All of these options support calling COM Automation Interfaces and Microsoft exposes the task scheduler through a series of Task Scheduler objects.
Task Scheduler Reference
CPU activity aside, a Windows service running all the time also consumes memory. In fact, every version of Windows has less services.
Why Windows 8 Uses So Much Less Memory Than Windows 7
I would use Timer.Tick. Thread.Sleep blocks the thread and you can not abort the thread nicely when you shut down your service.
I would recommend the Windows Service as you are just duplicating its functionality otherwise.
If InstallShield doesn't support adding to the task scheduler, then can you get InstallShield to run a batch script or a small .net app after install to add it to the task scheduler?
As long as your requirements for scheduling are very simple (as they currently are), I think the service approach is fine.
Personally, I don't really like the windows scheduler because I find it unstable and annoying to maintain (admittedly, I haven't tried the new version in Windows 2008).
I would probably go with a scheduling library like Quartz.Net if I were to build an application with more advanced scheduling requirements.
If you dont have scheduling app like autosys, windows service should be better option, also I dnt see any harm in thread.sleep, it is meant to pause app and utilize
0% cpu
My issue is pretty simple.
I have an application that should be executed automatically once a day. I have no prior experience with this kind of scenario (some time ago I worked with IBM Control-M but guess that it is way more complete, complex and expensive =))
I thought about two possible solutions:
Creating a Task inside Windows Task Scheduler, which would execute the application;
Implement the application as a Window Service which would run 24/7, but only would perform the needed actions depending on the current time.
Which are the advantages/disadvantages of each approach?
Is there another way to do this?
Thanks in advance.
If it only executes once a day (or so) then just do it as a regular command line app that is executed by the windows task scheduler. Task scheduler already has all of the UI necessary to determine when to kick off the program, pass in parameters and anything else related to the scheduling of the task.
The only real reason to do this type of function as a windows service is if it needs higher execution resolution than once a minute. However, the main downside to a windows service is that you would have to manage the logic for how often/when to kick it off. Another one is that the app is always running, which leaves open the possibility for leaked memory if your code has issues.
On Unix/Linux you would use a cron job schedule a task to be executed. MS Windows' version is called the Task Scheduler and it is already a service that run 24/7 and performs the needed actions depending on the time.
Create a repeating task with the Task Scheduler to run your application. Creating, installing and configuring a service application is not exactly trivial. It's a much more involved process than creating a standard Forms or command line app and you don't need to do it anyway.
http://msdn.microsoft.com/en-us/magazine/cc164015.aspx
http://www.dotnetmonster.com/Uwe/Forum.aspx/dotnet-csharp/70633/Waitable-Timer-in-C
Another library that might be of interest is Quartz.NET