Distributed Component Object Model (DCOM) is a proprietary

Proprietary software

Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...

 Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 technology for communication among software components distributed across networked computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

s. DCOM, which originally was called "Network OLE

Object Linking and Embedding

Object Linking and Embedding is a technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control eXtension , a way to develop and use custom user interface elements...

", extends Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

's COM

Component Object Model

Component Object Model is a binary-interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages...

, and provides the communication substrate under Microsoft

Microsoft

Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

's COM+ application server infrastructure. It has been deprecated in favor of the Microsoft .NET Remoting

.NET Remoting

.NET Remoting is a Microsoft application programming interface for interprocess communication released in 2002 with the 1.0 version of .NET Framework. It is one in a series of Microsoft technologies that began in 1990 with the first version of Object Linking and Embedding for 16-bit Windows...

, a part of their .NET Framework

.NET Framework

The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...

.

The addition of the "D" to COM was due to extensive use of DCE/RPC

DCE/RPC

DCE/RPC, short for "Distributed Computing Environment / Remote Procedure Calls", is the remote procedure call system developed for the Distributed Computing Environment...

 (Distributed Computing Environment/Remote Procedure Calls) – more specifically Microsoft's enhanced version, known as MSRPC

MSRPC

Microsoft RPC is a modified version of DCE/RPC. Additions include support for Unicode strings, implicit handles, inheritance of interfaces , and complex calculations in the variable-length string and structure paradigms already present in DCE/RPC.- Example :The DCE 1.0 reference implementation...

.

In terms of the extensions it added to COM, DCOM had to solve the problems of

• Marshalling
  Marshalling
  Marshalling may refer to :* Marshalling * Marshalling * Aircraft marshalling* A marshalling yard in railroading* Doctrine of Marshalling - an equitable concept in the law...
  
   – serializing and deserializing the arguments and return values of method calls "over the wire".
• Distributed garbage collection
  Garbage collection (computer science)
  In computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
  
   – ensuring that references held by clients of interfaces are released when, for example, the client process crashed, or the network connection was lost.

One of the key factors in solving these problems is the use of DCE/RPC as the underlying RPC mechanism behind DCOM.