Re: Configuration singleton ATL-COM-Server

Howie Meier <>
Tue, 11 Dec 2007 15:41:05 +0100
On Mon, 10 Dec 2007 09:34:44 -0800, "Brian Muth" <>

COM singletons are completely unnecessary.

Imagine two clients that instantiate the same COM class from a COM executable. Both instantiations live inside the same address
space (that of the COM executable) and can share the same data through global variables, or (my preference) static class variables.
Each client can get at that data through properties or method calls on their own COM object. And the client is still responsible for
lifetime control of their own object. IMHO, this is a much better approach.


Thanks Brian,

ok, i can make the variable static. I have forgotten this. Must i do
Lock() or Unlock() to access the variable ?


"Howie Meier" <> wrote in message


i want to configure an ATL-COM Server as singleton. This COM-module
should be a bridge between two different applications. It should share
the data between the 2 apps.

Can someone give me a short step-by-step descrition what to do ?

I will do this with my knowledge as novice.
- Create new project "ATL-Project"
- At "Application-Settings" i will choose "Executable"
- With menu "Project" i will add a new class
- Choose class under "ATL" ATL-Simple-Object
- I will give it a shortname eq. ABC_SOW in the "Names" dialog.
- Under Options i will choose "Apartment" , "DUAL" and Aggregation on
YES. (Connectionpoints are not used for this bridge).
- In the class header-file i will add "DECLARE_CLASSFACTORY_SINGLETON"
as classfactory.
- In the same class i will add a local attribute. "long
- in the class-wizzard i will add a property with put and get function
at the IABC_SOW- Interface. Type=LONG, Propertyname = ALong
- Now i fill in the cpp-code for the functions like this:
*pVal = m_thisisalong;
return S_OK;

m_thisisalong = newVal;
return S_OK;

Is this the right way to make the bridge COM Component ?

Thanks in advance,


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