which one to use windows services or threading

Question

Hi,

We are having a web application build using asp.net 3.5 & sql server as database which is quite big and used by around 300 super users for managing around 5000 staffs. Now we are implementing SMS functionality into the application which means the users will be able to send and recieve sms. Every two minute the sms server of the third party is pinged to check whether there are any new messages. Also sms are hold in queue and send every time interval of 15 to 30 minutes.

I want this checking and sending process to run in the background of the application all the time, even if the user closes the browser window. I need some advice on how do i do this ?

Will using thread will achieve this or do I need to create a windows service for it or are there any other options ?

Regards

Vinay

More information:

I want to execute a task in a timer, what will happen if I close the browser window, the task wont be completed isnt`it so.

For example I am saving 10 records to the database in a time interval of 5 minutes, which means every 5 minutes when the timer tick event fires, a record is inserted into the database.

How do i run this task if i close the browser window.

I tried looking at windows service but how do i pass a generic collection of data to it for processing.

Please give me some insight on how to do this .

Answer 1

Distinguish between what the browser is doing and what's happening server-side.

Your Web App is sitting server-side waiting for requests from whatever browsers may be running, and servicing those requests, in servicing those requests I guess it may well put messages on a queue and have a look in a database for any new messages.

You want the daemon processor, which talks to the third-party SMS, to be triggered by time rather than by browser function. Either of your suggestions would work:

• A competely independent service could run and work against the queues and database.
• Your web app, which I assume is already a service, could spawn a thread

In either case we have a few technical questions of avoiding any race conditions between the browser-request processing and the daemon - but databases and queueing systems can deal with that.

So I would decide between stand-alone daemon and background thread like this:

1. Which is easier to implement? I'm a JEE developer, I know in my app server I have an API for specifying code to be run accordng to a timer, the API deals with the threading issues. So for me that's very easy. I don't know what you have available. Timers are not quite as trivial as they may appear - so having a reliable API is beneficial. If this was a more complex requirement, where the daemon code were gnarly and might possibly interfere with the WebApp code then I might prefer to keep it conspicuously separate.
2. Which is easier to deploy and administer? Deploy separate Web App and daemon, or deploy one thing. In the JEE world we could have a single Enterprise Application with all the code, so that's a single thing to deploy, start and control.

One other thing to consider: Scaling and Resilience. You might choose to have more than one copy of your web app running, either to provide fail-over capabilities or just because you need the extra power. In which case how many daemons would you have? Would it be a problem to have two daemons running? You might need some extra code to mediate between two daemons, for example log in the database the time of last work, each daemon can say "Oh, my buddy balready did the 10:30 job, I'll go back to sleep"

Answer 2

I want to execute a task in a timer, what will happen if I close the browser window, the task wont be completed isnt`it so.

For example I am saving 10 records to the database in a time interval of 5 minutes, which means every 5 minutes when the timer tick event fires, a record is inserted into the database.

How do i run this task if i close the browser window.

I tried looking at windows service but how do i pass a generic collection of data to it for processing.

Please give me some insight on how to do this .

Answer 3

There really is no thread or service choice, a service can (and usually is!) multi threaded, a thread can start a service.

There are three basic choices you can:-

Somehow start another thread running when a user logs in -- this is probably a very poor choice for what you want, as you cannot really keep it running once the user session is lost.

Write a fully fledged windows service which is starts on OS startup and continues running unitl the server is shutdown. You can make this dependant on the SQLserver service, so it starts after the DB is available. This is the "best" solution but may be overkill for your purposes. Aslo you need to know the services API to write it properly as you need to respond correctly to shutdown and status requests.

You can schedule your task periodically using either the Windows schedular, or, preferably the schedular which is built in to SQLServer, I think this would be the most suitable option for your needs.