Re: COM... is it the best model so far?

Recently, i am examining different component model or framework
deployed in different systems.
What are you people think about the aggreagation or extensibility of
COM?

Even though COM has been successful for many years, IMHO COM is weak
on aggregation or component composition point of view.
For example, creating new component out of existing component
(aggregation) or creating new component from component interactions
(component composition) is hard to do with COM.

There are several component models which seperate the implementation
of component from the usage or composition.
For example,
each component only specifies "required interface" and "provide
interface".
there should be a glue component or container component that are
responsible to instantiate inner components and retrives the
interfaces from them in order to configure or map "required interface"
to "provide interface".

This has several advantages. Consider below cases.
(1) component A need to use interface IB provided by component B. In
COM, component A needs to know CID of component B and IID of interface
IB in order use it. In other words, A is tightly coupled with
component B. In future source code need to be changed if component A
want to use interface IB implemented by component C which exhibits
better performance. If we seperates configuration out of component A,
no source changes are needed on component A. We only need to update
container component. Only dependency component A has is the type of
interface or IID that it requires. It doesn't matter which component
provides this "required interface" since container component figures
out and configures it when instantiating component A.

Such approach also has some drawbacks, particually in dynamic aspect.

Compared with COM, what are the drawbacks of such component
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