I need to create an application that will run on a server and be able to be configured to run commands at certain times. For instance, there will be a web interface allowing a user to set an engage time and a disengage time. Once those values have been saved by the user I need for the server to be able to fire off those commands precisely at the time specified each day.
I would also need to be able to set single use non recurring events that would occur... maybe 10 minutes from the time an event was triggered and have a command fired off when that 10 minute timer goes off.
I've already got a class library written that has the engage and disengage commands exposed. I would hope to be able to integrate this into whatever solution I end up with and simply be able to make calls directly to the class. Alternatively I could also compile the class library into an executable and have commands issued to it via command line. I'm hoping to not have to do the latter.
I've never written anything like this before. I've peeked a bit at Windows Services, but there is a lot of chatter out there saying that it isn't necessarily the best option. Can someone please guide me in the right direction please?
A windows service is not a bad idea, its perfect for this kind of application. Unless you end up using standard windows scheduled tasks as the trigger for your command, you need some sort of process that is always running to contain your scheduler. A windows service is an excellent candidate for this.
Using a windows service in conjunction with Quartz.NET and some sort of persistence layer so you can store your schedules (in case you need to restart the service or it crashes etc) would be a good way to go.
Alternatively, you could write an application that just adds and removes windows scheduled tasks, but considering you have existing class libraries, using Quartz.NET will fit in well with your existing libraries.
easiest solution:
make a console exe and run under scheduled task in windows.
Let web page to accept user input and modify a configuration file.
Related
I am trying to develop an application that will scan a website, get data from the website and save that data into database 3x per day at given hour that can be set in xml configuration file.
As an addition group of users can trigger the start of the application manually max few times per day.
I am looking for pros and cons of using a windows service for this solution or should I set a 3 scheduled tasks that will run the console application?
If I will decide to use a windows service then what is the best way to trigger a manual start of the service while the service is already running? The group of users will have some kind of web interface to trigger manual start.
This could be easily done using a scheduled task. I would just set a 3x scheduled tasks that will run the application at given time and the group of users could just start the .exe file from the web interface. However how to only allow the user to run a manual trigger only if application is not already running?
Since the UI is ultimately in web, and thus the service itself won't need any UI, I would go with Windows service which can be triggered to start by the user through web or automatically as the time comes (by its internal code).
Then, either:
In the service it has something to indicate its status as running which can be captured by the web app to see it, or,
In the web, there is mechanism to request/monitor the service status
Is quite flexible I think. I would go with whichever is easier.
I picked the task scheduler option for my case. It was easier to implement the manual triggering by users mechanism.
Pros - Triggers can be added easly using the taks scheduler library.
This may seem very elementary, but I don't really have any experience in this realm - all my experience has been on the web side of things.
I need to create a process of some sort that will repeatedly query an API (around 5 times a second), get the results from the API (in JSON format), and then my process will do what it needs to do with the results (in my case, insert them into a SQL database). These details don't really matter to the scope of the question I have, I just want to give you an idea on what I'm trying to achieve in case someone wants to recommend a better way of doing it.
My first thought was to create a console app that basically never quits (unless I specifically tell it to). Is a console app the way to go for this? The idea is I'll have a VM set up which will host my solution, including this "process" I create. I'm not all too familiar with Windows Services, or Windows Tasks, but I probably need to write some custom code so therefore I imagine I can't use the Windows Task Scheduler, am I right?
Once options would be to create a Windows Service which is the OS-level implementation of a long running process. To do so in C# you may wish to read through some tutorials online, perhaps starting with the MSDN Walkthrough. You should also read about Windows Services in general and the differences between a service and a regular user process (mainly the fact that services have no UI and can't interact with the user directly, and some of the other security considerations).
Other options may be to leverage a framework such as WCF or similar.
So this is my first stint with programmatically creating windows service or scheduled tasks and I am confused which one to choose. I had a look at various articles like http://weblogs.asp.net/jgalloway/archive/2005/10/24/428303.aspx , scheduled task or windows service and some more but can' t really decide btween the two
Here is my scenario :
My application will pick up the code paths of a few dlls from the db , execute the DLLs using MSTest.exe and log back the results to the Db. this will probably be repeated every 2-3 hours . Now I am leaning a bit towards scheduled tasks since i won't have to worry about memory related issues but need some expert advice on this.
P.S. : The DLLs contain test methods that make calls to web services of applications deployed on various servers
Thanks in advance for the help
A Scheduled Task would be more appropiate for your scenario. I don't think it make a lot of sense building a scheduling mechanism on a windows service when OS already provides scheduling infraestructure.
A Windows service is more appropiate for processes that have to respond to events at any moment and not at specific and fix periods. That's why they are running all the time. An example of this is the SQL Server Service.
An exception of this could be a task that needs to run every second or so. In that corner case, a Window Service could be the best solution. For your specific schedule, I have no doubts that a scheduled task would fit much more better.
Although this post is several months old, here's a possible resolution in case it's helpful to others for the "Run whether the user is logged on or not" issue : start with a console project then change type to Windows App as mentioned at Run code once and exit formless app: Windows Forms or WPF... does it matter?:
“If you never show a UI, you should start with a WinForms project (WPF projects set extra project metadata that you don't want), then delete the reference to System.Windows.Forms.dll. Alternatively, start with a console project, then change the Output type to Windows Application.”
Let me give a back ground for everybody before I go to my problem. My company hosts website for many clients, my company also contracts some of the work to another company.
So when we first set up a website with all the informations to our clients, we pass that information to the other company we contracted and three of us have the same data. Problem is once the site is up and running, our clients will change some data and when ever they do that we should be able to update our contracted company.
The way we transfer data to the contracted company is by using a web service (httppost, xml data). Now my question is what it the best way to write a program which sends updated data to the contracted company everytime our clients change some data.
1) Write a windows service having a timer inside my code where every 30min or so connects to the database and find all changes and send it to the contracted company
2) Write the same code as #1 (with out the timer in it) but this time make it a simple program and let windows scheduler wake it every 30min
3) Any other suggestion you may have
Techenologies available for me are VS 2008, SQLServer 2005
Scheduled task is the way to go. Jon wrote up a good summary of why services are not well suited for this sort of thing: http://weblogs.asp.net/jgalloway/archive/2005/10/24/428303.aspx
A service is easy to create and install and is more "professional" feeling so why not go that way? Using a non-service EXE would also work of course and would be slightly easier to get running (permissions, etc.) but I think the difference in setup between the two is nearly negligible.
One possible solution would be to add a timestamp column to your data tables.
Once this is done, you can have one entry in each table that has the last collected time by your contracted company. They can pull all records since that last time and update their records accordingly.
A Windows Service is more self contained, and you can easily configure it to start up automatically when the OS is starting up. You might also need to create additional configuration options, as well as some way to trigger the synchronization immediately.
It will also give you more room to grow your functionality for the service in the future.
A standalone app should be easier to develop though, however you are reliant on the windows scheduler to execute the task always. My experience has been that it is easier to mess up things with the windows scheduler and have it not run, for example in cases where you reboot the OS but no user has logged in.
If you want a more professional approach go with the service, even though it might mean a little bit more work.
A windows service makes more sense in this case. Think about what happens after your server is restarted:
With a Windows Application you need to have someone restart the application, or manually copy a shortcut to the startup folder to make sure the application gets launched
OR,
With a Windows Service you set it to start automatically and forget about it. When the machine reboots your service starts up and continues processing.
One more consideration, what happens when there is an error? A Windows application would likely show an error dialog and wait for input before continuing; whereas a service would log the error in the event log and carry on.
I have been working on many applications which run as windows service or scheduled tasks.
Now, i want to make sure that these applications will be fault tolerant and reliable. For example; i have a service that runs every hour. if the service crashes while its operating or running, i d like the application to run again for the same period (there are several things involved with this including transactions of data processing) , to avoid data loss. moreover, i d like the program to report the error with details. My goal is to avoid data loss and not falling behind for running the program.
I have built a class library that a user can import into a project. Library is supposed to keep information of running instance of the program, ie. program reads and writes information of running interval, running status etc. This data is stored in a database.
I was curious, if there are some best practices to make the scheduled tasks/ windows services fault tolerant and reliable.
Edit : I am talking about independent tasks or services which on different servers. and my goal is to make sure that the service will keep running, report any failures and recover from them.
I'm interested in what other people have to say, but I'll give you a few points that I've stumbled across:
Make an event handler for Unhandled Exceptions. This way you can clean up resources, write to a log file, email an administrator, or anything you need to instead of having it crash.
AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(AppUnhandledExceptionEventHandler);
Override any servicebase event handlers you need in the main part of your application. OnStart and OnStop are pretty crucial, but there are many others you can use. http://msdn.microsoft.com/en-us/library/system.serviceprocess.servicebase%28v=VS.71%29.aspx
Beware of timers. Windows forms timers won't work right in a service. User System.Threading.Timers or System.Timers.Timer. Best Timer for using in a Windows service
If you are updating on a thread, make sure you use a lock() or monitor in key sections to make sure everything is threadsafe.
Be careful not to use anything user specific, as a service runs without a specific user context. I noticed some of my SQL connection strings were no longer working for windows authorizations, etc. Also have heard people having trouble with mapped drives.
Never make a service with a UI. In fact for Vista and 7 they make it nearly impossible to do anyway. It shouldn't require user interaction, the most you can do is send a message with a WIN32 function. MSDN claims making interactive services is bad practice. http://msdn.microsoft.com/en-us/library/ms683502%28VS.85%29.aspx
For debugging purposes, it is way cool to make a service run as a console application until you get it doing what you want it to. Awesome tutorial: http://mycomponent.blogspot.com/2009/04/create-debug-install-windows-service-in.html
Anyway, hope that helps a little, but that is just a couple thing I poked around to find on my own.
Something obvious - don't run all your tasks at the same time. Try to schedule them so only one task is using some expensive resource at any time (if possible). For example, if you need to send out newsletters and some specific notifications, schedule them at different times. If two tasks need to clean up something in the database, let the one run after another.
Also schedule tasks to run outside of normal business hours - at night obviously.