Question

I have a service application built in Delphi that works great. It does exactly what I want it to do and all is happy. All is fine until I want to run two (or more) instances of that service on a single machine. Since the service name is hard coded into the program (via the Name property of the service), I can only install the service once on any given computer. If I try to modify the Name property at run-time, the service does not respond unless the Name property is set to the same thing that was set during design time.

I have done a workaround for this where I have all of the code that is not interacting directly with the service control manager encapsulated out into separate unit(s). Then I write a separate Delphi project for each instance that I want of the service that has just enough code to launch itself and start running the main code.

This method is, in my opinion, ugly and is certainly inefficient. It works okay for two instances, but then we need a third and a fourth and …

Is there any way that I can modify my code so that I have just one Delphi project that can install and run itself as multiple service instances with some simple run-time input (e.g. command line flag)?

Or perhaps a broader question: Is there a ‘right way’ to accomplish goal?

Answer 1

You haven’t made it clear what you have tried to change in the TService subclass.

Have you added a ‘BeforeInstall’ handler?

Something like:

procedure TServiceMain.ServiceLoadInfo(Sender : TObject);// new method, not an override begin   Name := ParamStr(2);   DisplayName := ParamStr(3); end;  procedure TServiceMain.ServiceBeforeInstall(Sender: TService); begin   ServiceLoadInfo(Self); end; procedure TServiceMain.ServiceCreate(Sender: TObject); begin   ServiceLoadInfo(Self); end; 

If you do this regularly, subclass TService to do thie in the Constructor instead.

You should do the same in the BeforeUninstall as well – point both events at the same method.

C:\>servicename /install MyService 'My Service Description'