What is COM?

[jon_davis24]

I am very confused about all these knew technologies . . . Could somebody answer my questions?

- What IS an ActiveX exe?
- How is an ActiveX exe different from a regular EXE?
- Is the coding for an ActiveX exe different than a reg. exe?
- What is COM?

Thanks,

JD


P.S. I know it isn't in the right forum, but what is XML and .NET, anyway? How is .NET different?

[jim mcnamara]

COM is a way of providing resources for a program - these resources are only available thru a defined interface. What goes on behind the interface is of zero concern to your program.
The interface is made of things like properties and methods.
Events are defined and raised by the COM object, but they are not necessarily a part of any interface.

An activeX exe is a COM module that runs in it's own process, separate from the program that makes use of it's controls.
ActiveX .exe are very different from regular .exe files.
Coding uses the same rules, but there are gotchas and a lot of things to learn about - Properties, Property pages, events, etc.

There is a good beginning book that uses only VB -

VB COM by L Thomas from WROX Press.

[jon_davis24]

Thanks for helping me . . . I'm still confused, but I guess that's a start to answering my questions!

[list=1]
I searched for that book you mentioned (VB COM by L Thomas from WROX Press) however I had no luck in finding it. Could you provide me with a link to a site where I can buy it (i.e. Amazon.com)?
Also, is COM important to know? When would I actually need to know it?
[/list=1]

Thanks again,

JD

[robinm]

COM or the Component Object Model is a specification.
The COM standard defines the following;

A common way for applications to access and perform operations on Objects.

A mechanism for keeping track of whether an object is in use and deleting it when it is no longer needed.

A mechanism for applications to exchange objects

A way to identify objects and to associate them with applications that understand how they are implemented.

(excerpt from DAN APPLEMAN - Developing COM/ACTIVEX Components)