What is COM and DCOM?

kailash

Oct 7th, 2005

COM component object model
a component which can attached with any component and create a new component (aggregation) each component must have a 128 bit id that must be register on ther registry of windows
Dcom distributed component model
a component which can be used on network

harish

Oct 20th, 2005

COM is a Specification defined by microsoft in order enhance the productibility of one application in to other.COM is a FrameWork which when implemented both the application can talk each other.COM is set of rules and it is language independent. COM talk about Language interability. and reusablility.

Aidan

Mar 2nd, 2006

"Productibility", "Language interability and reusability"? Can you clarify what that means? Thanks.

Deepu Abraham K

Jun 13th, 2007

COM

1/ Component Object Model (COM) is a standard introduced by Microsoft.

2/ COM is a language-neutral way of implementing objects.

3/ It can be used in different environments, even other than where it was created

4/ It can be used across the machine boundaries

5/ A good COM component (well written) allow re-usability. The component implementers have to just know about its interface.

6/ It has been implemented on several platforms, COM is primarily used with Microsoft Windows.

DCOM

1/ Nothing but Distributed COM

2/ This will use RPC mechanism for communication

3/ DCOM had to solve the problems of

- serializing and deserializing the arguments and return values of method calls "over the wire".

- ensuring that references held by clients of interfaces are released when, for example, the client process crashed, or the network connection was lost.

Chaitanya Sagar

Jul 19th, 2007

COM( component object model) is a specification/ guide line document for creating the reusable components.

By Com we can achive
Language Independent (by implementing Dual interfaces IDispatch for Nonpointer based languages and VTable for Pointer based languages)
Location transparency ( By guid and clsids stored in windows registry we can have location transparency which cannot be done using dlls.
Immutable:Old clients are not affected if we change the old component by new one, this cannot be done in case of dlls which is also known as dll hell.