Question

I wrote two small C++ applications, one of which is an ActiveX container embedding some ActiveX control. This container application knows the IUnknown* referencing the ActiveX control.

The other application is a client which shall interact with the ActiveX control in the former application. However, I don’t know how to get a handle on the control in the client application. Simply transporting the pointer value of the IUnknown* from the server to the client won’t work of courses due to independant address spaces.

Is it somehow possible to “duplicate” a handle to some COM object so that the newly created handle can be used by other processes? I’d like to have COM do the RPC work for me. Otherwise, I’d need to do all COM calls in the server application and do all the RPC myself. :-/

Answer 1

You may want to look at RPC in general, and COM Proxies.

A proxy resides in the address space of the calling process and acts as a surrogate for the remote object. From the perspective of the calling object, the proxy is the object. Typically, the proxy’s role is to package the interface parameters for calls to methods in its object interfaces. The proxy packages the parameters into a message buffer and passes the buffer onto the channel, which handles the transport between processes. The proxy is implemented as an aggregate, or composite, object. It contains a system-provided, manager piece called the proxy manager and one or more interface-specific components called interface proxies. The number of interface proxies equals the number of object interfaces that have been exposed to that particular client. To the client complying with the component object model, the proxy appears to be the real object.