COM overview

Posted on 2006-11-07
Last Modified: 2013-11-25

I am doing some self study and need your help. I am NOT a programmer, but am interested in learning how it all comes together. All that mentioned I need an identifiable explanation as I have read several sites, but am looking for simpler explanation so I can better interpret those articles.

What is a COM object?
 How are they utilized?
How do they work?

I would greatly appreciate real life examples to help relate to your explanation.

Question by:link334
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LVL 10

Expert Comment

ID: 17893621
Basically COM (Component Object Model) is a binary programming standard. It enables you to build reusable 'binary compatible' software.

Don't want to waffle on here, so heres a link for further info :

Author Comment

ID: 17893784

Thanks for the reply. This was one of the first articles I read. Unfortunately it is greek and am unable to parse it.

"Microsoft COM (Component Object Model) technology in the Microsoft Windows-family of Operating Systems enables software components to communicate. COM is used by developers to create re-usable software components, link components together to build applications, and take advantage of Windows services. The family of COM technologies includes COM+, Distributed COM (DCOM) and ActiveX® Controls."

Software components? Are the COM's a file type such as a DLL that are able to be shared?

Sorry for being so ignorant.
LVL 13

Accepted Solution

AngryBinary earned 150 total points
ID: 17894009
COM can be thought of, at it's simplest, as a binary module that can be reused by other programs.

To give a practical example, Microsoft provides a COM for Text-to-Speech. If you want to write a program that utilizes text to speech on a Windows platform for which this particular COM is compatible (anything after Win98, if I'm not mistaken), rather than reinvent the entire text-to-speech technology, your program can pass text to the COM object, which will in turn handle the talking part for you. On the user's machine, they will need to have your program, and the COM binary file (often a DLL or OCX) registered.

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Expert Comment

ID: 17894096
.dll, .ocx and .exe can all be COM objects.

Think of it as metaphor - like a steering wheel....

You wrote the code for the steering wheel, you compile it to a binary standard that enables any other person requiring a steering wheel to use.
The wheel will come compiled (black box).

Author Comment

ID: 17895434

Awesome description! Makes since. One thing for clarification on the last sentence.

"On the user's machine, they will need to have your program, and the COM binary file (often a DLL or OCX) registered."
Who provides the COM (ocx and DLL)? Microsoft and/or Application programmer? And, how does the COM get registered?


Expert Comment

ID: 17895451

In COM you expose the interfaces and hide actual implementation to the outside world. Any program can make use of the services of your COM object by making use of the interface method it exposes. The services will be implemented by you in a different class. The user will be least bothered to know how the services are implemented.
LVL 10

Assisted Solution

Kinger247 earned 100 total points
ID: 17896940
The Com binary file can be made or sourced from anyone. It just does a particular job. Instead of you writing the code to do the job, the Com control will do it for you. It will need to be registered on the machine if the file is not located in the same folder as the calling program.
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Expert Comment

ID: 17897144
these are some search engine

gud collection of information:-

GO SEARCH THERE...........

sorry !!! self study ??
The best option is goto a gud search engine and search for it !! You will definatly get help !!
This aint a good Study ... i think searching will allow u to go through the other notes too...

Author Comment

ID: 17898025
theGhost k8,

The following is a link to some information you should find helpful in building character.
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Expert Comment

ID: 17904109
i take no offence but i dont know if it has hit the weak point !!
i;ve never intended towards wounding the feelings..... but it really does... i appologiZ for the same !!

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