Describing COM (Component Object Model)

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  Sam Hobbs15y agoPosted Mar 17, 2011, 6:08 PM

  What is the difference between the COM and the DCOM object models? I am not aware of any difference, and everything I have read says that they are the same. I am not aware of anything that needs to be done differntly in a COM server or client (the source code) to use the COM object as a DCOM object. Also, for what it is worth, COM evolved from "Object Linking and Embedding" (OLE). Also, for anyone trying to understand how ActiveX relates to COM, think of ActiveX as being Microsoft's marketing people's intentional attempt to confuse us into thinking that ActiveX was an earth-shaking new development.
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    Nipun Tomar15y agoeditedPosted Mar 18, 2011, 12:03 AMEdited Mar 18, 2011, 12:07 AM

    As per my Understanding: 1. Any DCOM object is yet a COM object (DCOM extends COM) and any COM object may participate in DCOM transactions. DCOM introduced several improvements/optimizations for distributed environment, such as MULTI_QI (multiple QueryInterface()), security contexts etc. DCOM demonstrated importance of surrogate process (you cannot run in-proc server on a remote machine. You need a surrogate process to do that.) DCOM introduced a load balancing. 2. COM is a local component object model on one single machine. DCOM is a distributed component object model working across several machines. DCOM = COM + "Secure" Networking Transactions.
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    Sam Hobbs15y agoPosted Mar 18, 2011, 1:54 AM

    I am not a COM specialist, but I did spend time trying to learn about it; see my: http://simplesamples.info/Windows/COMandActiveX/index.php
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    Sam Hobbs15y agoPosted Mar 18, 2011, 1:51 AM

    At the object model level, is there any difference? Is there something that needs to be done in a program (the source code) to make it a DCOM program? Certainly an in-process server needs a surrogate, but that is done externally from the source code, right?