I'm implementing an email reminder to remind the student of returning the books before expired date.
I know Window Service can achieve that but since the machine will have restriction for installing the Window Service, so is there any other ideas?
You don't need a Windows service to perform background tasks, just use Windows scheduled tasks. You can write an exe or batch file and schedule it as frequently as you like.
If the server won't let you run scheduled tasks, you can always create the task as an action in a MVC controller and create a scheduled task on another machine that calls your action.
Related
I am building a medication reminder system using Ruby on Rails to be deployed on heroku.
Using this system a doctor will enter a patient's medication details including medication name, dose as well as timing details and the app will then notify the patient via sms when its time to take his/her medicine.
I have developed the application but I am stuck on the sms part since that involves running a process over and over again until the medication's period has elapsed.
I want to be able to run a script from a rails app that will repeatedly query the database and when it is time to send a sms it will dispatch it to the patient. This cannot function in the normal request/response web cycle.
I explored rubygems that allow developers to create background jobs such as rufus scheduler and resque but I can't seem to figure out how to go about doing this.
Please help I am open to all types of suggestions. I am using Twilio for sending sms
I don't know about resque/rufus, but I know that sidekiq has the ability to queue jobs, but have them delayed till a certain time.
https://github.com/mperham/sidekiq/wiki/Delayed-Extensions#advanced-options
You'd need to look into how exact the delay is (ie. what sidekiq's polling frequency is) depending on your needs, but I would suspect this would work well.
It would require another dynamo or whatever heroku calls it these days.
I use delayed_job using the run_at param to send scheduled SMS via Twilio from Heroku.
I have a send_message method on my message model that does the actual send with the Twilio API. I chose to create a custom job with Delayed Job so when I schedule the message:
Delayed::Job.enqueue my_custom_job, :run_at => TIME_I_WANT_TO_SEND
Using a the heroku worker to run the background task of sending has been very reliable.
Since you're deploying to Heroku, reading their documentation about scheduling jobs is a must for you:
https://devcenter.heroku.com/articles/scheduler
I am using TFS 2010 for build service. I need to send an email if the build is running for longer time.
For ex: Suppose the build normally runs for 10 mins, but now if the build is running for more than 20 mins... i need to send an email notification.
May I have your help on this?
This functionality is not available out of the box. This can however, make a great feature request, raise it for consideration here => http://visualstudio.uservoice.com/forums/121579-visual-studio
However, to get this to work here is what you can do... Write a tfs build activity which using the tfs api extracts the last build execution time and insert that at various places in the process workflow ideally before and after each work flow task to check how much time has the build already consumed while measuring this against the expected time. Use the email notification task to send out an email accordingly.
Here is an example that shows u how to get the last build details, http://blogs.microsoft.co.il/blogs/shair/archive/2011/01/11/tfs-api-part-33-get-build-definitions-and-build-details.aspx and here a custom task example http://msdn.microsoft.com/en-us/library/t9883dzc.aspx
Alternatively, query the TFS Build Queue and check the runtime of the builds in progress. When any of the builds exceeds the defined thresholds, send the email. This can be done in a windows service with relative ease.
You'd use the TFS Client Object Model to query the builds like this. Tarun already provided a nice link to that.
I am building an application which will send status requests to users (via email & sms) on a regular basis. I want to execute the service each hour which will:
Query the database for all requests that need to be sent (based on some logic)
Send the requests through Amazon's Simple Email Service (this is already working)
Write a record of the status request notification back to the data store
I am considering wrapping up this series of operations into a single controller with an end point that can be called remotely to kick off the process within the rails app.
Longer term, I will break this process out into an app that can be run independently of my rails app, but for now I'm just trying to keep it simple.
My first inclination is to build the following:
Controller with the following elements:
A method which will orchestrate the steps outlined above (and can be called externally)
A call to the status_request model which will bring back a collection of request needing to be sent
A loop to iterate through the pending requests, which will:
Make a call to my AWS Simple Email Service module to actually send the email, and
Make a call to the status_request model to log the request back to the database
Model:
A method on my status_request model which will bring back a collection of requests that need to be sent
A method in my status_request model which will log that a notification was sent
Since this will behave as a service that gets called periodically from an outside scheduler I don't think I'll need a view for this operation. (Will, of course, need views to show users and admins what requests have been sent, but that's later...).
As someone new to Rails, I'm asking for review of this approach and any suggestions you may have.
Thanks!
Instead of a controller which Jeff pointed out exposes a security risk, you may just want to expose a rake task and use cron to invoke it on an hourly basis.
If you are still interested in building a controller, look at devise gem and its single access token, token_authenticatable, for securing the methods you are exposing.
You may also want to look at delayed_job or resque to offload the call to status_request and the loop to AWS simple service to a background worker process.
You may want a seperate controller and view for the log file so you can review progress on demand.
And if you want to get real fancy use Amazon SNS to send you alerts when the service reaches some unacceptable level of failures, backlog, etc.
Since you are trying to invoke this from an outside process, your approach should work. You could also have a worker process that processes task when they are there.
You will need routes to expose your service, and you may want to also make security decisions. How will the service that invokes your application authenticate so all others can't hit it at will?
Another consideration should be how many emails are you sending. If there are enough, we may want to look into the fact that writing this sort of loop is going to be extremely top heavy; and may affect users on the current system if it's a web application.
In the end, there are many ways to do this. I would focus on the performance/usage you expect as well as security. There's never one perfect way to solve a problem like this, and your way should just be aware of the variables it will need to be operating within.
Resque and Redis might be helpful to you in scheduling and performing operatio n .They are simple and superfast, [here](http://railscasts.com/episodes/271-resque] is a simple tut on same.
Following a specific action the user takes on my website, a number of messages must be sent to different emails. Is it possible to have a separate thread or worker take care of sending multiple emails so as to avoid having the response from the server take a while to return if there are a lot of emails to send?
I would like to avoid using system process or scheduled tasks, email queues.
You can definitely spawn off a background thread in your controller to handle the emails asynchronously.
I know you want to avoid queues, but another thing i have done in the past is written a windows service that pulls email from a DB queue and processes it at certain intervals. This way you can separate the 2 applications if there is a lot of email to be sent.
This can be done in many different ways, depending on how large your application is and what kind of reliability you want. Any of these ways should help you achieve what you want (in ascending order based on complexity):
If you're using IIS SMTP Server or another mail server that supports a pickup directory option, you can go with that. With this option, instead of sending the emails directly, they are saved first in the pickup directory. Your call will immediately return after the email is saved in the pickup directory, so the user won't have to wait until the email is sent. On the other hand, the server will try to send the email as soon as it's saved in the pickup directory so it's almost immediate (just without blocking the call).
You can use a background thread like described in other answers. You'll need to be careful with this option as the thread can end unexpectedly before it finishes its job. You'll need to add some code to make sure this works reliably (personally, I'd prefer not to use this option).
Using a messaging queue server like MSMQ. This is more work and you probably should only look into this if you have a large scale application or have good reasons not to use the first option with the pickup directory.
There are a few ways you could do this.
You could store enough details about the message in the database, and write a windows service to loop through them and send the email. When the user submits the form it just inserts the required data about the message and trusts the service will pick it up. Almost an email queue which you said you didn't want, but you're going to end up in a queue situation with almost any solution.
Another option would be to drop in NServiceBus. Use that for these kinds of tasks.
I typically compile the message body and store that in a table in the db along with the from and to addresses, a subject, and a timestamp indicating when the email was sent. Then I have a background task check the table periodically and pull any that haven't been sent. This task attempts to send each email and updates the timestamp accordingly. One advantage of storing the compiled message body up front is that the background task doesn't have to do any processing of context-specific data, and therefore can be pretty darn simple.
Whenever an operation like is hingent upon an event, there is always the possibility something will go wrong.
In ASP.NET you can spawn multiple threads and have those threads do the action. Make sure you tell the thread it's a background thread, otherwise ASP.NET might way for the thread to finish before rendering your page:
myThread.IsBackground = true;
I know you said you didn't want to use system process or scheduled tasks, but a windows service would be a viable approach to this as well. The approach would be to use MS Queue, or save the actions needing to be done in a DataBase table. Then have a windows service check every minute or so and do those actions.
This way, if something fails (Email server down) those emails / actions can still be done.
They will also be recorded for audit's (which is very nice to have).
This method allows you're web site to function as a website while offloading these tasks to another service. The last thing you need is for multiple ASP.NET processes to be used up waiting for emails to send. let something else handle that.
I'm making a Rails application.
In the one action I need to spawn a long running process.
This is not a problem. I can fork new process using spawn gem or some other.
But some time after process has been spawned,
user must be able to pass additional data to that process.
Sure, I can fork process which will listen a UNIX socket,
store socket address in the HTTP session and
communicate with that process using drb protocol when user will require to pass new data to process. But I think it is not best solution and it will be a problem to deploy an application to the hosting.
What is the easy way to do that?
Can the additional data go into the database, and the process checks there for the "new data"?
I suggest going up-level. Use delayed_job to handle the spawning and initial setting of parameters for your job.
You can modify delayed_job's dbms model to add fields for the additional information that you want to later send to the job.
Then your flow would be:
Submit using delayed_job. Store the id of the jobs table. If stock de;ayed_job doesn't give you the job id, then modify delayed_job as necessary.
Add the additional data to the field in the jobs table
If your main job needs data back from the forked job, then you could also have a db fields for that.
You should try to design your application to mimimize the amount of message passing needed. Otherwise you'll need to design a message protocol. Can be done, but it is work that you should try to avoid.
Can't you use a thread and communicate with it via two queues, one for input to the thread, and one for the thread's responses?