Best way to implement windows service as “worker”

Question

I have an ASP .NET page which allows users to start programs. These programs and the parameter are stored in a database and a windows service then executes these programs. The programs are dlls which implements my IPlugin interface, so I can add them at runtime (the dlls are loaded at runtime so I can add them at runtime without compiling or restarting the service).

I created the ASP .NET page, more than 10 programs (plugins) and the windows service. Everything is running fine, but I think the implementation of the windows service is bad.

The windows service periodically queries the database and executes the needed program if it gets a new entry. The service can run multiple programs in parallel (at the moment 3 programs).

Currently my service method looks like this:

 while (Alive)
        {
                // gets all running processes from the database
                Processes = Proc.GetRunningProcs();

                // if there are less than 3 processes running and
                // a process is in queue
                if (ReadyToRun())
                {
                    // get next program from queue, sets the status to 
                    // runnig and update the entry in the database
                    Proc.ProcData proc = GetNextProc();
                    proc.Status = Proc.ProcStatus.Running;
                    Proc.Update(proc);

                    // create a new thread and execute the program
                    Thread t = new Thread(new ParameterizedThreadStart(ExecuteProc));
                    t.IsBackground = true;
                    t.Start(proc);
                }

            Thread.Sleep(1000);
        }

I have a method that queries the database for entries with status 'Canceling' (if a user cancels a program, the status will be set to 'Canceling') and does a Thread.Abort().

Is there a better practice? Like using tasks with the cancel mechanism or is the whole concept (storing the processes in database (program name, parameter, status,... and querying this information periodically) wrong?

Answer 1

As an alternative you can use some existing libraries for your purposes like Quartz.NET http://www.quartz-scheduler.net/ . It takes care about job persistence, job scheduling and many other things. All you must do to create an adapter and put it into Windows Service.