Runtime Callable Wrapper

A Runtime Callable Wrapper (RCW) is a <a href="/facts/Proxy_pattern/CHHyzXbd">proxy</a> object generated by the <a href="/facts/.NET_Framework/J6QDAUhP">.NET</a> <a href="/facts/Common_Language_Runtime/4Y0cUdkd">Common Language Runtime</a> (CLR) in order to allow a <a href="/facts/Component_Object_Model/2DtIAufW">Component Object Model</a> (COM) object to be accessed from managed code. Although the RCW appears to be an ordinary object to .NET clients, its primary function is to <a href="/facts/Marshalling_(computer_science)/NhcdrmhR">marshal</a> calls and data between a .NET client and a COM object.
For example, a managed application written in <a href="/facts/C_Sharp_(programming_language)/UC2gxeyb">C#</a> might make use of an existing COM library written in <a href="/facts/C%252B%252B/Et0F2qn9">C++</a> or <a href="/facts/Visual_Basic_6/7QMXM6fP">Visual Basic 6</a>, via RCWs.
The runtime creates exactly one RCW for each COM object, regardless of the number of references that exist on that object. The runtime maintains a single RCW per process for each object. If you create an RCW in one application domain or apartment, and then pass a reference to another application domain or apartment, a proxy to the first object will be used.

Runtime Callable Wrapper open-in-new

Runtime Callable Wrapper