Richard Monson-Haefel wrote:
>
> I agree with Jim completely. Business component reuse seems to be more myth
> than reality. I can not imagine, given my project experience in several
> different domains, how an off the self business component could be reused across
> industries or even business within the same industry. Domain models from one
> business to the next are very different, not to mention persistence
> requirements. The only exception, of course, is if the component is part of
> larger framework. IBM San Francisco is an example where there is reuse, but in
> this case you have to purchase the whole thing including the vertical tower
> specific to your domain.
>
> How successful has MTS been in this area?
It doesn't *seem* to be a myth. It *is*.
It took 7 years for C++ to standardize on a string -- it is unlikely
that you will be able to buy and sell generic bank account bean
classes. (Perhaps you could do so with account instances ... anything
can happen on eBay!)
I once did a project for a large shipping company a couple of years
back where I was tasked with coming up with a common object model
across the company. This is obvious in hindsight, but I learnt the
hard way that no two departments had a common understanding of a
simple object like an aircraft. For a long-range planner, the average
speed and the containing capacity in gross terms is all that
matters. The short-range planner had to worry about the tail number,
flight and maintenance hours, breakdown of capacity by freight type,
taxiing speeds vs. cruising speeds etc. The accounting department
couldn't be bothered with any of these details. Their focus was on gas
consumption, depreciation etc. Neither the schema nor the
functionality was reusable across departments. The only thing we could
possibly conclude was that where there was an overlap (aircraft tail
number, for example), the data should be kept in one consistent
format. Reuse of business components is a myth. It is not something
that can be helped by EJB or MTS.
On the hand, visual components have been succesfully marketed and
reused. The reason for this is that the desktops have been
standardized; the matrix in which these components are used is
standard. This is like a consortium of banks (or one all-powerful
bank) dictating to the world what an account object will look
like. 'Tis unlikely you'll get this kind of agreement even within
different departments of one bank.
Components are useful because they allow systems to be factored into
more easily understandable chunks. They draw lines that you can use
for scheduling projects and for dividing labor. I suggest that you
concentrate on these issues instead of expecting reuse. Finally, even
if reuse were a possibility, I'd suggest you do a couple of iterations
of your project before you decide on a reusable chunk.
-Sriram
BEA/Weblogic
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