Logging Application Events using a Simple Windows Service in C#

In this article we are going to focus on the steps required to create a Windows Service using Visual C# Windows Service Template in Microsoft Visual Studio 2012. We will create a Windows service and then Deploy it on the machine. We will see how to log information in the Application Event log when the Service is either Started/Paused/Resumes/Stopped.

About Windows Service:
1.Microsoft implements many services in every operating system.
2.With Windows Service we can create a simple data mining application or a complicated multitier, multi-tier business solution.

Step1: Open Microsoft Visual Studio 2012. From the File Menu, Select New Project. For the Project Type, expand Visual C# and then select Windows. In the Templates Pane, select Windows Service. In the Name textbox, type MyDemoService and then Click OK.


Step2: In the solution explorer you will see Service1.cs which represents the service. Rename it to DemoService.cs. Right click DemoService.cs file and select View Code.

We will find OnStart and OnStart methods in the DemoService class along with the class constructor. Notice that both the methods are blank but these methods are required for the service to run properly.
OnStart method represents the entry point into your service. This method is called by the Service Control Manager(SCM) when the user clicks Start on the Control Panel Services screen. OnStart method takes the "args" as an array of strings argument which contains the parameters defined in the Administrative Tools->Services->Service Properties.

The OnStop method represents the exit point of our service. Here we can add clean up code. This method is called when the user clicks Stop on the Services tab under Administrative Tools.

OnPause and OnContinue are the other two important methods.
OnPause allows a user to temporarily suspend your service without shutting down.
OnContinue allows the service to resume where the service was paused.
To use the OnPause and OnContinue methods, first enable these features in the service as follows:
1.Double click DemoService.cs in the Solution Explorer to open the DemoService.cs Design window.
2.Left click in the Design window to view the DemoService.cs Deisgn Properties tab.
3.Set the CanPauseAndContinue property to True.

Step3:Write code for OnStart,OnStop,OnPause and OnContinue events: Now we will write code in the OnStart,OnStop,OnPause and OnContinue events. We will write Try Catch blocks so that we can handle exceptions occurred in the service.

  protected override void OnStart(string[] args)
        {
            try
            {
                EventLog startLog = new EventLog("Demo Application");
                startLog.Source = "Demo Service";
                startLog.WriteEntry("Demo Starting ", EventLogEntryType.Information, 1000);
                startLog.Dispose();
            }
            catch (Exception ex)
            {
                //Catch the exception to avoid unhandled errors and stop the service.
                this.Stop();
            }
        }

  protected override void OnStop()
        {
            try
            {
                EventLog stopLog = new EventLog("Demo Application");
                stopLog.Source = "Demo Service";
                stopLog.WriteEntry("Demo Stopping ", EventLogEntryType.Information, 1001);
                stopLog.Dispose();
            }
            catch (Exception ex)
            {
                //Catch the exception to avoid unhandled errors and write the output to the debug window.
                Debug.WriteLine("Error stopping service: " + ex.ToString());
            }
        }

protected override void OnPause()
        {
            try
            {
                EventLog stopLog = new EventLog("Demo Application");
                stopLog.Source = "Demo Service";
                stopLog.WriteEntry("Demo Pausing ", EventLogEntryType.Information, 1002);
                stopLog.Dispose();
            }
            catch (Exception ex)
            {
                //Catch the exception to avoid unhandled errors and write the output to the debug window.
                Debug.WriteLine("Error Pausing service: " + ex.ToString());
                this.Stop();
            }
        }

protected override void OnContinue()
        {
            try
            {
                EventLog continueLog = new EventLog("Demo Application");
                continueLog.Source = "Demo Service";
                continueLog.WriteEntry("Demo Continuing ", EventLogEntryType.Information, 1003);
                continueLog.Dispose();
            }
            catch (Exception ex)
            {
                //Catch the exception to avoid unhandled errors and write the output to the debug window.
                Debug.WriteLine("Error resuming service: " + ex.ToString());
                this.Stop();
            }
        }