Spawning and executing a Worker process in Azure - c#

The google has really failed me on this one. I am new to Azure and am only intermediate at .NET
I have an Azure solution going and I've written some code in a Web Role which runs great. What I would like to do now is move some of this code into an Azure Worker, which will be initialized by a controller function in the Web Role
What on earth do I need to do to get this going locally? I have created the Worker project within the SLN. I just need to know how to fire it up and run it.
I think part of my problem is I am assuming these workers behave like Heroku workers... is this the case? Because what I need is something like a queue system (a bunch of "worker tasks" in one big queue).
A lot of the links I've found for tutorials seem to tap dance around how to actually initialize the process from a Web Role.

Workers in Windows Azure are not tasks; they're entire VMs. To make your life easier, memorize this little detail: Web Role instances are Windows Server 2008 with IIS running, and Worker Roles are the same thing but with IIS disabled.
When you added that worker role to your project, you actually now have a new set of virtual machines running (at least one, depending on the instance count you set). These VMs have their own OnStart() and Run() methods you can put code into, for bootstrapping purposes.
If you grab the Windows Azure training kit, you'll see a few labs that show how to communicate between your various role instances (a common pattern being the use of Windows Azure queues). There's a good example of background processes with the Guestbook hands-on lab (the very first lab).

More info on this, as I've gotten it going now..
If you're coming from a Heroku background, then an Azure Worker is more or less the function in Rails that you'd actually execute with the queue. Unlike Heroku queued operations, an Azure Worker just runs endlessly and keeps polling for new stuff to do... hence the templated sleep(10000) in the Run() function.
The most conventional way I've found to make a Web and Worker talk to each other is by queue messages via Azure ServiceBus which is currently NOT emulated, meaning you need a functioning Azure account to make this work, and it will work even if you are running locally. You just need internet access.
A ServiceBus message can pass an entire object over to the Worker (so long as the Worker proj has the right dependencies in it), so that's kind of nice.

I think you're just having trouble starting the azure emulator along with your worker/web roles? Just set the azure configuration project as the start up project and run that. It'll boot up the emulator along with all your roles.

Related

Run a single while(true) on Azure

I'm new to Azure and I need to DoSomeWork() in Azure. This DoSomeWork() should be running periodically, every N minutes or so. However, DoSomeWork() can't be executed twice at the same time. In other words, any DoSomeWork() execution can't start before a prior DoSomeWork() execution finished.
I've been taken a look at Azure Web Jobs, particularly Continuous Azure Web Jobs. This seems the way to go but it's not clear on how to start, especially with the starting code that you get in VS:
static void Main()
{
var config = new JobHostConfiguration();
if (config.IsDevelopment)
{
config.UseDevelopmentSettings();
}
var host = new JobHost(config);
// The following code ensures that the WebJob will be running continuously
host.RunAndBlock();
}
There is also Functions class that takes an input a QueueTrigger decorated parameter, but I don't want the code to be triggered by any queue message or so.
How can I get a simple Console.WriteLine("hello world") running e.g. every minute but without overlapping? If Azure Web Jobs is not the way to go, what should I use instead (should be Azure-based)?
As mentioned in the comment, azure webjobs supports TimerTrigger feature(scheduled WebJob) which can be ran every xxx minutes as per your need.
It's quite simple when using azure webjob. For example, in visual studio, just create a console project -> Add this line of code: Console.WriteLine("hello world") -> then build the project -> then zip all the necessary files including the .exe into a .zip file -> at last, upload the .zip file into your webjob, and set the schedule(like execute the code every 5 minutes).
Please refer to this doc for more details about creating a scheduled WebJob.
You can also consider using other azure services which supports timerTrigger feature, like azure function.
WebJobs can be complicated to set up and maintain. Especially when dealing with a CI/CD pipeline. I have a few running right now and am getting ready to move them into one of the following more dependable and maintainable solutions:
The way we set up scheduled work is to use an Azure Function that runs via CRON schedule. It's super dependable and durable since it's managed by Azure. You just set it up, throw your code up and the rest is up to Azure to make sure it fires off when you configured it to.
If you want to do this in your own application, take a look at running a background service in an ASP.NET Core application. You can run a timer in the background service that will fire off and do some work. Keep in mind that if your app scales horizontally, you will be running two timers, which probably isn't good in your situation.
You could do something fancy like setting up a Azure Function to hit an endpoint on your WebAPI at a scheduled time. Then you could send the work to a BackgroundService which is singleton, so you could block a second request if you are currently running your job.
We tend to go the last route. Azure fires off a timer, the function executes, sends a message to an endpoint, the endpoint places work in the background.
There are tons of options outside of what I mentioned, but these are the only ones I have had the privilege to architect.

creating azure worker rules from a vm

is it possible to start Worker Role Instances dynamically from a c# application running on azure windows vm?
in azure i have a Medium virtual machine, on it there is a c# console application that runs automatically on 11:00PM daily and it keeps processing data until about 7:00AM, my data is getting bigger and thus needs more time to be processed and i need to finish processing all data before 5:00AM.
is it possible to use Worker rule to run an instance of the application an pass it a part of the data to process?
note that my process makes http requests to external websites and the processed data gets written to a mongodb.
i am not sure where to start, and i am not sure if using worker rules is better than creating couple vms.
in general how would you solve this problem with the tools available on azure?
Is it possible to start Worker Role Instances dynamically from a c#
application running on azure windows vm?
Absolutely Yes. In order to do so, you would need to consume Service Management API. You could either write code yourself to consume this API or there's a Windows Azure Management Library available to do so which you can install from Nuget. To learn more about this API, you may find this blog post useful: http://www.bradygaster.com/post/getting-started-with-the-windows-azure-management-libraries.
Generally speaking Worker Roles are equivalent to Windows Services in the sense that both are used to perform background tasks. Since you're performing background tasks through your VM, I can't see any reason why you can't do the same though a Worker Role instance. My recommendation would be to go through tutorials available online or Windows Azure Platform Training Kit to become familiar with Worker Role concepts and how you could make use of them in your project.
For your specific scenario you may want to look at the auto scale rules that are now available; In the configuration for the worker role, in the Azure Management Console, you can specify, for example, that you want at least two workers running between certain times each day.
The Service Management API gives you a lot more control, but the auto scale is quick and easy to start with.
Incidentally, if the work your worker has to do can be divided into atomic chunks, then you may want to use a storage queue to write all the tasks to and then have the worker role pull tasks off that queue. You can then configure the autoscale to monitor the length of the queue and start and stop workers as required.

Windows Azure - background/scheduled tasks?

Previously, there was worker role in Azure, now I can't see one - so what to use for background/scheduled tasks, like maintainance, email sending, etc, should I create virtual machine and create windows services there or is there easier way?
The definitive (current) guide to this FAQ is Guarav's Building a Simple Task Scheduler in Windows Azure — which, as it turns out, is not that simple, and it is not really suited to Azure websites (but rather roles).
The simplest solution is to create RESTful (ish) routes (controllers, etc) using something like the MVC Web API and get a cron job scheduler to kick them off. Recently I have been using the Aditi cloud scheduler which kicks of those jobs for you, and is free (5000 calls per month) in the marketplace.
There is this new scheduler http://www.windowsazure.com/en-us/services/scheduler/
Windows Azure Scheduler allows you to invoke actions—such as calling HTTP/S endpoints or posting a message to a storage queue—on any schedule. With Scheduler, you create jobs in the cloud that reliably call services both inside and outside of Windows Azure and run those jobs on demand, on a regularly recurring schedule, or designate them for a future date. This service is currently available as a standalone API.
If you are using Azure Web Sites (and they are very good) then there is the new WebJobs feature that lets you poke a http(s) endpoint or run scripts on a schedule.
Web and Worker Roles are part of the Cloud Service model, and both exist and haven't gone anywhere.
As stated in the comments to your question, the portal does not facilitate construction of these roles; this is something you'd create, either through Visual Studio, Eclipse (worker role), or PowerShell.
And you don't need a worker role for background tasks. As mentioned in dozens of other answers, worker and web roles are templates for Windows Server virtual machines. Since the VMs are stateless and restart each time from the same baseline, the template shapes what gets installed at startup.
You can run background tasks as a thread in either a web role or worker role. So if you wanted to, you could run all your background tasks within the same web role instances as your web site.
I recommend working through some of the basic examples in the Azure Training Kit, which walk through creating different roles from Visual Studio.

Start a process on Azure remotely

I would like to be able to start a number of concurrent processes (command line programs) on Azure remotely. I need to be able to make a call from a C# program to start these processes off. What would be the best approach to this?
Set up an Azure VM with IIS
Install the various .exes that I want to run.
Write and install a web service on the box that can take parameters and start the processes on the server.
Is there an easier way to do this using Azure though? I am not familiar with Azure VMs or worker roles etc.
Thanks!
You could make use of Azure Worker Roles and Windows Azure Storage for that purpose. What you could do is either package the executables along with the worker role package so that they are always available in your role or you could save them in blob storage so that you can download on demand into your worker role. From your calling application, you can put messages in a queue which will be constantly polled by your worker role. The message will contain enough information (for example exe to invoke etc.). Once the message is received, the worker role will execute the executable.
Hope this helps.

Is there a way to have code run on a time schedule in an ASP.NET web app?

I have an ASP.NET web app providing access to a database on the server. What I need is a way to run code in the background on a given schedule that auto-updates the server database from another source.
I know how to do this in a windows app by adding a timer, linking up a function to the timer tick event and starting the timer. I do not know how to do this in a web app.
Is there a start-up event for a web app or somewhere where I can start this background process regardless of whatever any users are doing on the site?
You should not do this in an ASP.NET website - this is a major no-no. You are correct in thinking to use a timer on a background .exe. You should look into creating either a Windows Task (a console .exe executed by the server task timer), or a Windows Service. I would suggest the Windows Service as that is standard practice.
If you have access to the computer hosting your site I would write a little app that was run from the Task Scheduler.
The web server is not meant to handle long-running background tasks. It's the wrong tool.
If you dont have access to the hosting computer then I would suggest building some kind of interface whereby another computer rebuilt the database and uploaded it. I'm using the terms "interface" and "upload" in the loosest, broadest sense - apply your own definition.
I was searching for a solution myself couple of months ago, and even though I haven't found enough time to try it so far, I guess I can share the link with you. Maybe you'll find it helpful.
If yes, please, let me know here.
http://quartznet.sourceforge.net/
How to use Quartz.net with ASP.NET
you can use Windows Service or use Timer Control (In the Ajax Category)
Or
As other answers have stated, doing this full function - updating a database and scheduling it as an ASP.NET app is using the wrong tool for the job.
ASP.NET can be used to update a database - that's perfectly valid. Where it breaks down is in the timer. ASP.NET apps aren't meant to be long-running, which is necessary for the timer to work.
If you can do it, I'd strongly suggest using the approach others have suggested - a Windows Service or a Scheduled Task.
However, if you have no access to the actual server, other than to post ASP.NET code - you can't install a service and you can't set up a Windows app to run on a scheduled basis, here's an out-of-the box idea.
Set up a web service or ASPX page that does the update, and then call that page from a scheduled task on a machine you DO control.
So if this was at http://www.someserver.net/updatedb.aspx, there's no reason you can't set a scheduled task on your own PC to call that URL.
I'd consider this a last-ditch solution to be used only if you can't do one of the other options.
The global.asax.cs file has a method that is fired when your application starts: Application_Start. You can hook up your timer method in that event. Just beware, depending on how IIS configured, your app pool may shutdown. For example, if no one hits the site in 20 minutes for example. Just make sure if you HAVE to have this run every X minutes that you have IIS configured to ALWAYS be running and start your app. This is harder than it sounds. In the end, you may want to go with a regular windows scheduled task.

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