COM, DCOM

Distributed Component Object Model (DCOM) is a proprietary Microsoft technology for communication among software components distributed across networked computers.

DCOM is the TCP/IP of objects. It could runs without IIS.

Wiki
http://en.wikipedia.org/wiki/Distributed_Component_Object_Model

DCOM Technical Overview
http://msdn.microsoft.com/en-us/library/ms809340.aspx

DCOM Architecture
http://msdn.microsoft.com/en-us/library/ms809311.aspx


COM VS DCOM

COM
Component Object Model (COM) is Microsoft's object-oriented programming model that defines how objects interact within a single application or between applications. In COM, client software accesses an object through a pointer to an interface (a related set of funcations called methods) on objects. Both OLE and ActiveX are based on COM. IBM's verion of COM is called SOM.
Component Object Model. A component software architecture from Microsoft, which defines a structure for building program routines (objects) that can be called up and executed in a Windows environment. This capability is built into Windows 95/98 and Windows NT 4.0. COM provides the interfaces between objects, and Distributed COM (DCOM) allows them to run remotely. COM objects can be small or large. They can be written in several programming languages, and they can perform any kind of processing. A program can call the object whenever it needs its services.

DCOM
Distributed Component Object Model. Additions to the Component Object Model (COM) that facilitate the transparent distribution of objects over networks and over the Internet. DCOM is part of the specification managed by The Open Group for deployment across heterogeneous platforms.
(Distributed Component Object Model)—An extension of the Microsoft Component Object Model (COM) that allows COM components to communicate across network boundaries. Traditional COM components can only perform interprocess communication across process boundaries on the same machine. DCOM uses the Remote Procedure Call (RPC) mechanism to transparently send and receive information between COM components (ie, clients and servers) on the same network. DCOM was first made available in 1995 with the initial release of Windows NT 4.