Events in C#

CSharp · Console

/Program.cs

using System;
					
public class Program // Consider this your home form
{
	public void Main()
	{
		var serviceController = new ServiceController();
		serviceController.ServiceStateChange += ServiceController_ServiceStateChanged;
		serviceController.StartServices();
	}
	
	private void ServiceController_ServiceStateChanged(object sender, ServiceControllerEventArgs e)
	{
		// Add to listbox or do whatever you want. I am just printing.
		Console.WriteLine(e.Message);
	}
}

public class ServiceController
{
	public event EventHandler<ServiceControllerEventArgs> ServiceStateChange;
	
	public void StartServices()
	{
		Service[] services = new Service[] // Sample services data
		{ 
			new Service { Name = "MSMQ", Status = "Stopped" },
			new Service { Name = "W3SVC", Status = "Running" }
		};
		
		string message = null;
		
		foreach(Service s in services) 
		{
			if(s.Status == "Stopped") 
			{
				s.Start();
				// Assuming it starts almost immediately. If not, you could follow same pattern for 
				// Service class where an event will be raised once service is "actually" started.
				if(s.Status == "Running") {
					message = string.Format("Service {0} is {1}", s.Name, s.Status);
				}
			}
			else if(s.Status == "Running") {
				message = string.Format("Service {0} is already {1}", s.Name, s.Status);
			}
			
			// Now tell subscriber (home form) about this.
			OnServiceStateChange(message);
		}
	}
	
	private void OnServiceStateChange(string message)
	{
		var serviceStateChangeHandler = ServiceStateChange;
		if(serviceStateChangeHandler != null)
		{
			serviceStateChangeHandler(this, new ServiceControllerEventArgs { Message = message });
		}
	}
}

// You could have custome delegate type for event to return string message.
// But IMO this is much cleaner, and as per MSFT guidelines.
public class ServiceControllerEventArgs : EventArgs
{
	// You can also return Service instance
	// Just including Message for now 
	public string Message { get; set; }
}

// for demo purpose, represents individual service.
public class Service
{
	public string Name { get; set; }
	public string Status { get; set; }
	
	public void Start() {
		Status = "Running";
	}
}