I have a simple solution with 3 projects:
Asp.Net MVC4 Web app - the main website
Console App - task runner
Console App - task runner
I wish to use MassTrasnsit to serve as a queue so that actions on the website (like send email) do not block the website, instead being published to the queue and taken care by the task runners.
My question is: Where should I initialize the queue, the web app, one of the task runners or create a separate console app for that?
ps. The console apps will be windows services when running on production servers.
As creating the queue is a one-off operation and you will probably want to tweak the default permissions, it would be best to create the queue in advance using a separate console app. Note that the publisher (the web app) and the consumers (the task runners) need a queue each, and that if they are on different servers then you will need to create the queues on each server.
Related
We have web application developed in .NET Core and is hosted on azure. We want to use HangFire for report scheduling.
Our application is multitenant so it will have load of its own, So I want to run these background processes into different server. HangFire has option of Placing Processing into Another Process as Using Console applications or Using Windows Services.
I have gone through HangFire Doc but there is no clear explanation of how this main application (which is .NET CORE) connects to this Console application?
https://docs.hangfire.io/en/latest/background-processing/placing-processing-into-another-process.html
I came across this question but still is not clear to me
How to run Hangfire as a separate process from the main web application?
Your AspNet .Net Core application (the hangfire client) will not communicate directly with the console application (the hangfire server).
Communication is done trhough the storage (the database) : client declares new tasks in the storage, and the server polls the storage (or is notified by the storage depending on the storage technology, like Redis) to execute the tasks.
You need to ensure communication of both client and server with the storage, but not between the client and the server.
I am evaluating Hangfire for an upcoming ASP.net Core project that has several scheduled and reoccurring tasks that need to execute independently of users clicking on web pages. I know that HangFire can do this if the web application is started because a request has come in. I need to know whether or not HangFire can execute a scheduled task between being rebooted and the first web request coming in.
Example: Web server is rebooted at 11pm, and no web requests will come in to cause the web server to spin up until 5am the next morning. A scheduled task needs to be performed at 1AM. Will Hangfire execute this task even though the web application hasn't been started by an incoming request?
If it can, is there a certain setup I need to do to allow this?
Details, if needed:
We are going to be using Kestrel hosted in a windows service and sitting behind an NGINX reverse proxy. This setup could be modified if needed to make HangFire meet this requirement.
When running under IIS it would be a real problem, see Making ASP.NET application always running
But it should not be problem for ASP.NET CORE with kestrel, see
It is not necessary for ASP.NET Core, because application is exposed
by a console application that it already always on – there are no
timeouts, no suspends and other optimization techniques yet. All you
need to do is to use supervisor as written in the official docs for
Linux, or use Windows Service with automatic start time, when running
on Windows.
Is it possible to run an IHostedService on only one instance of a scaled out Azure App Service in ASP.NET Core? Or would the solution be to run this IHostedService in its own app service with one instance?
I have a BackgroundService that runs once a day and sends out reports via email. This service will run twice a day at the same time when my App Service is scaled out to 2 instances, resulting in two identical emails being sent.
How can I solve this problem?
It's better to break out things into separate apps, and that's the case here as well. If you only want one instance of your hosted service, you should break it out into a separate project and deploy one instance of that. If you deploy it inside your app, there will be an instance per instance of your app; there's no way around that, refer to this thread.
With Hosted Services, there is an instance running of that hosted service for every deployment of your website which can be an issue if you only want one instance of that “process” running at anytime. You can program around this by creating your own locking mechanism, but obviously webjobs gets this out of the box. So you can use webjob running as a singleton to achieve what you want. Refer to the article about Hosted Services In ASP.NET Core.
I have a Rails app running on AWS elastic beanstalk on a web tier. I want to send email notifications to users so I'm using sqs to send messages to a queue:
sqs = AWS::SQS.new
sqs.queues.named("messaging_queue").send_message("HELLO")
and then I would like to take these messages off the queue using a worker tier instance.
My issues is that when I create the worker tier instance from the console it asks for the application version which defaults to the latest deployed version to my web tier. I don't want to upload my entire web application to the worker, just the code responsible for performing the emailing.
What's the best way to do this? I could upload a zip but I would like to just use git
Can you refactor the code that is responsible for sending emails into a separate library? That way you can create a new web app which just wraps around the email functionality in your library and runs on a worker tier environment. The worker daemon will post messages to your new worker tier app which will then send the email. That way you do not have to deploy your entire code base to your worker tier environment.
You can use git and eb to achieve this. Your worker tier application version and webapp application version can be managed in different branches or in your case it seems better to keep them in different git repositories. If you wish to use branches then you can read about the eb command "eb branch", it may be useful.
Read more about eb here.
Is it possible to use NServiceBus to publish and consume messages in the same application, specifically a web application?
In the future we will almost certainly need to maintain a separate long running service to process messages generated by this application, and this is why we are hoping to use NServiceBus from the start, but right now it would be nice to just start up the consumer and the publisher when the web application starts. This will make testing and deployment far easier for us.
I presume I will need to reference the NServiceBus.Host.exe and start up the process in the global.asax, but need help on what exactly I need to call to do this.
This is not a mode of deployment that is supported out of the box. While you could make this work by manually creating an additional appdomain for the second NServiceBus endpoint, you'd also likely need to give it a custom configuration source, and of course its own queue.
All in all, I'd recommend keeping it as a separate process, even if it is on the same box. That being said, you can create a second web app to host it rather than using the generic host if you don't want to manage windows services in addition to web apps.
Hope that helps.