What is DCOM?
DCOM, or Distributed COM, is essentially a "network enabled" COM. A DCOM client and object can communicate over a network as transparently as a regular COM object and client can communicate on a single machine. From a programming perspective, writing a DCOM object is identical to writing a COM object with one additional step: DCOM places a remote procedure call (RPC) layer beneath COM interfaces, so that member functions of an interface map to remote procedure calls. These RPCs "marshal" the function's arguments and return values across a network from a DCOM client to a DCOM server. DCOM accomplishes this marshalling process via the industry standard (with a few Microsoft "enhancements") RPC mechansism. If you've ever worked with RPC, you'll have no problem with this addition to COM. If you haven't, it's probably best to learn basic COM first, and then the RPC layer will be a relatively small additional step. o
