Can a Singleton Class inside a DLL be shared across processes?

Question

I am creating a custom .net hardware framework that will be used by other programmers to control some hardware. They will add a reference to our DLL to get to our hardware f

Answer 1

There are ways to do it as mentioned above. But it is clumsy if you use WCF or remoting. Please try interprocess thread sync techniques.

For more info read the online free e-book on threading

http://www.albahari.com/threading/

Specially see the cross process sync constructs here ...

http://www.albahari.com/threading/part2.aspx#_Synchronization_Essentials

Answer 2

Simply calling a singleton property in a different assembly from two different processes will create different instances of that class.

But you can easily share information between processes using .Net Remoting, or fire interprocess events if you only need simple signaling (EventWaitHandle).

[Edit:] To make it look like a Singleton to your callers, you can expose a class which will internally use Remoting to instantiate a singleton, and then return the instance transparently. Here is an example which (I think) does that: http://www.codeproject.com/KB/dotnet/remotingsingleton.aspx

Answer 3

To add to the Kevin's answer, your constructor for your class Resources should really be made private for it to be a true singleton, otherwise nothing is stopping someone from creating a new instance of the Resources class through the constructor. This doesn't solve your problem, but it does stop one from misusing the Singleton.

Answer 4

Yes it is possible to share a singleton amongst several processes. However you will need to take advantage of a technology which supports interprocess communication in order to achieve this result.

The most popular technologies which allow you to share out your object fairly directly are Remoting and WCF.

Giving an example of sharing a singleton with either of these is beyond the scope of an SO answer. But there are many tutorials on the web for each of these. Googling either technology plus singleton should put you on the right path.

Answer 5

You cannot use a singleton to sync across applications. Each runs in its own application space, and as a matter of security cannot access memory/objects/etc. from the other without a method of communication (like remoting) To sync the two they would have to remote into a third program.