First of all sorry of asking such a dumb question, I am quite a newbie in asp.net.
So, I am supposed to do something periodically, say I am owner of site heartpatients.com (hypothetically) and I want that for each of my site user who visits the site, a message to be shown after 2hrs "Take your pills". so, basically this is all my question, how am I supposed to show this message after every 2hr (or 4, 6 whatever time)after, also how can I customize time.
One more thing, say if I have this method in a WCF service, that shows this message, how can I call that service at a particular time, and that even configured by user (say someone is taking pills after 10hrs?) So how to call that service (that particular method in service) after the time specified by user passes periodically?
I hope I made my question quite clear.
Any help is appreciated.
ASP.NET generally isn't suited as a task scheduler. The nature of the web is as a request/response system. So a web application should just sit and wait for a request, generate a response, and be done.
For any kind of back-end scheduled task, I'd recommend either:
A Windows Service
A console application scheduled to run (I think Windows comes with a task scheduler)
There are pros and cons either way. For example, a Windows Service will run from boot time and has no console UI, and is generally very manageable from a server perspective. While a console application is traditionally simpler to write and debug.
These can still share code from your web application. If your business logic and data access and all that good stuff are in their own projects/assemblies then these other applications can use those assemblies just as well. (Of course, if everything in your web application is UI-bound, that's another question entirely.)
What concerns me the most is... How do you plan to show this message to a user? Is the user just sitting on your website for hours at a time and you need to remind them to take their meds? Or do you plan to send an email or something? Maybe the example you gave doesn't really explain what you're trying to do? I'm not sure.
Running tasks in the background is one thing, but it seems to me that an entire half of your overall equation (displaying a message to the user) is sort of glazed over and not really thought through.
Check out Quartz.Net: http://quartznet.sourceforge.net/
It enables you to schedule tasks to run using cron expressions:
http://en.wikipedia.org/wiki/Cron
Related
I have a classified web application developed with ASP.NET MVC and I need to implement a advert bump up option.
As a example if someone use this option (for 3 days) today at 10.15 AM, advert should bump up each day 10.15 AM for 3 days.
So I need a scheduler to execute some code to bring up the advert to top of the list.
Can someone explain me how approach this inside my ASP.NET MVC application or using any other 3rd party resource?
save on the database every time the user click on the option. and every time he clicks on the option check if he has click in the pass two days.
You will need to use a task scheduler service. It is not possible to create a scheduled task in ASP.NET MVC, because it simply listens and responds to HTTP requests. You could put your code to bump up the advert in an ASP.NET MVC controller, but you would still need something to send an HTTP request to trigger the controller at the given time. So there's probably not a great reason to put that code in a controller under most circumstances.
It is easy to set up scheduled tasks in most cloud computing environments. For example, in AWS you could write a Lambda function in C# and schedule it with a CloudWatch Events rule.
If your application is running on a Windows Server, the most robust way to implement a task scheduler would probably be to write a Windows Service application to call the task logic on a polling loop. It is also possible to create a console application and trigger it with the Windows Task Scheduler. This approach is quicker and easier to get up and running than developing a Windows service, but in my experience is more likely to fail and quit running without your knowledge. Either way, it will be important to make sure to write good logging and error notification code.
I'm sure there are also good 3rd party tasks schedulers out there too, I just haven't used any of them. Those are just some general guidelines, but if you want more detail on them just let me know and I can post some links.
I have an c# asp.net management system with a button that calls a SQL Server Query to get 90,000 strings of text in multiple languages and categorized into sections. This in turn is sorted and 150 Binary files made before saving as a .ZIP and emailing the user with the results. The total time to process this and email the results is about 6 minutes. In this time the Web Page is sat waiting for the whole process to complete. I would like to be able to press the start process button and then allow this to work away in the background while I continue using the web management system, but I am unsure what is the most efficient method for doing this. I initially created an asmx file thinking this would work but the result is the same and so I am now looking at async and await. Can anyone give me any pointers on this and let me know if I am on the right track. I am currently not getting anything back to let me know the process has completed successfully as I can handle this by emailing the user to say something went wrong. The reason for this is the user could be on any number of pages.
There are probably a few ways to go about tackling this problem. Your options will vary based on what version of .NET you are using, so I'll not post code directly; however, the you can implement the concept I describe using ASMX web services, WCF, MVC, and so on.
Start-and-poll Approach
The classic response for this kind of problem is to implement a StartSomething() method and a GetProgress() method. A very-simple example of this approach using ASMX-based web services is presented here.
In the example, one service method is used to start a process on a background thread. Myself, I would change the example by having the start method return a value to the client to identify which background process was started, as you could feasibly have several going on at a time.
The client then can call a separate method to get progress updates, and continue polling until the process is complete.
There are a number of reasons why you should prefer to do lengthy background processing in a non-IIS service. I recommend using a Windows service to protect yourself from IIS somewhat-randomly restarting your application pool in the middle of a big job.
WebSockets
Another option worth some exploration on your part is to use WebSockets, which allow the server to contact a modern browser when the process is complete. The main advantage of this approach is that the client does not need to busily poll the service for updates. Its primary disadvantage is that WebSockets are new enough that there are still plenty of browsers that could not be clients for such a service.
Good luck!
I am currently working on a project, this project is basically a web site which as its main function, runs a long calculation task (this task is made up of between 1-10 sub tasks) - (takes about 30-40 seconds to complete on average) and returns a result to the user, as it stands the code uses multiple threading in the site itself (which i don't really like the idea of), so the site continues to run after a button click, whilst this thread in the background continues the calculation.
I'd ideally like to move this calculation into a separate service, to stop the issues related to running threading in a web app. My idea is that it should be a separate service that runs every X seconds to see if any jobs are present in the database, if there are, run them, but i have little experience in writing a reoccurring windows service, and was wondering if anyone has any ideas on the matter, is this the right way to go about such a task, does anyone have any experience of doing something similar, and can anybody recommend any particular ways I should proceed?
I am working on a similar project. I was thinking about create a service, like you, but I didn't see the benefits in my case. I have to do some long calculations, and put it in the cache. I don't know if this is the best practice but what I did was to create a timer on global.asax, perform my calculations and put it into cache. When the request comes I give the last cached value.
I hope this help you.
In a situation like this I always prefer to create a tcp listener that accepts the requests from the clients. If I am using .net, my first choice would be wcf service with tcp or named pipe binding. Then when I receive a request, I start a thread to proceed the request. When the long running process finally ends, I return a callback to the client, which was a url that specified in the first request to the scheduler. IMHO this is the best way to do it.
However you may want to build your application on a proven framework like NServiceBus, RhinoBus, etc. You may implement the same business over them too.
I have a clockIn & clockOut module that records start time & end time for workers from an Asp.NET app.
I want to ask how to do cron job for asp.net application to see if a worker has not entered their time on that date or week and send an email notification to remind them to enter start time and end time.
ASP.NET is the wrong tool for the job. You would be better off either writing a Console Application that is run on a scheduled task, or a Windows Service that polls on a regular interval. ASP.NET is purely meant for a request/response model.
Either one can access whatever data store the website is reading from/writing to just as easily as the ASP.NET site can.
If you've done neither, the Console Application is by far the simplest to write and implement. Windows Services aren't all that bad, but involve extra overhead, including difficulty debugging, and the need to go through a special installation process as compared to the XCOPY deployment model possible with Console applications.
If you REALLY want to do it in ASP.NET, you can write an asp.net web page that does this, and use the Windows Scheduled Task to run it. The Scheduled Task can open up Internet Explorer to a specific page just as easily as it can run any executable. But I wouldn't recommend it. You'll forever have to close the IE window when the task is finished, and it's just really a "hackish" solution. I did it back when I was a pure web developer and didn't know any better, but not since.
Jeff Atwood posted on the Stack Overflow blog, titled as Easy Background Tasks in ASP.NET, in the early days of this site about a simple way to do background tasks in ASP.NET. If your tasks are relatively lightweight, this might not be a bad way. If you have a reason to really want to keep everything inside an existing ASP.NET app, this might be the way to go.
The gist:
At startup, add an item to the HttpRuntime.Cache with a fixed expiration.
When cache item expires, do your work, such as WebRequest or what have you.
Re-add the item to the cache with a fixed expiration.
Although its not technically a cron job, from within a website you can get the website to call a set page at X time of the day.
I have done this a few times via a web method call, which is called on the timer from the application start.
Basic explanation is here:
Call a webpage from c# in code
I am developing a asp.net site that needs hit a few social media sites daily for blanket friend/follower data. I have chosen arvixe business class as my hosting. In the future if we grow, I'd love to get onto a dedicated server and run a windows service, however since that is not in the cards at this point I need another reliable way of running scheduled tasks. I am familiar with running a thread timer from the app_code(global.aspx). However the app pool recycling will cause some problems with the timer. I have never used task scheduling like quartz but have read a lot about it on stackoverflow. I was looking for some advise as to how to approach my goal. One big problem I have using either method is that I will need the crawler threads to sleep for up to an hour regularly due to api call limits. My first thoughts were to use the db to save the starting and ending of a job. When the app pool recycles I would clear out any parts not completed and only start parts that do not have a record of running on that day. What do the experts here think? any good links to sample architecture of this type of scheduling?
It doesn't really matter what method you use, whether you roll your own or use Quartz. You are at the mercy of ASP.NET/IIS because that's where you want to host it.
Do you have a spare computer laying around that can just run a scheduled task and upload data to a hosted database? To be honest, it's possibly safer (depending on your use case) to just do it that way then try to run a scheduler in ASP.NET.
Somewhat along the lines of Bryan's post;
Find a spare computer.
Instead of allowing DB access have it call up a web service on your site. This service call should be the initiator of the process you are trying to do. Don't try to put params into it, just something like "StartProcess()" should work fine.
As far as going to sleep and resuming later take a look at Workflow Foundation. There are some nice built in features to persist state.
Don't expose your DB to the outside world, instead expose that page or web service and wraps some security around that. WCF has some nice built in security features for that.
The best part is when you decide to move off, you can keep your web service and have it called from a Windows Service in the same manner.
As long as you use a persistent job store (like a database) and you write and schedule your jobs so that they can handle things like being killed half way through, having IIS recycle your process is not that big a deal.
The bigger issue is that IIS shuts your site down if it doesn't have traffic. If you can keep your site up, then just make sure you set the misfire policy appropriately and that your jobs store any state data needed to pick up where they left off, you should be able to pull it off.
If you are language-agnostic and don't mind writing your "job-activation-script" in your favourite, Linux-supported language...
One solution that has worked very well for me is:
Getting relatively cheap, stable Linux hosting(from reputable
companies),
Creating a WCF service on your .Net hosted platform that will contain the logic you want to run regularly (RESTfully or SOAP or XMLRPC... whichever suits you),
Handling the calls through your Linux hosted cron jobs, written in your language of choice(I use PHP).
Working very well, like I said. No VPS expense,configurable and externally activated. I have one central place where my jobs are activated, with 99 to 100% uptime(never had any failures).