Re: Re[2]: What makes Java so special?

** Reply to note from Buck Calabro <mcalabro@commsoft.net> Mon, 24 Nov 1997 
10:40:23 -0500

> If we use OO to design our client properly, then the client has a clear,
> well defined standard interface to the server.  It is this interface which 
> makes the client application independent of the server platform. 

I gotta be honest, I don't see what OO design in the client has to do with
the server's interface. What if the server was written by a maniac and the
interface is cumbersome and confusing?

I am pretty sure that part of this will be dependant on how the server is
written.

> Don't forget that code re-use is the end-goal.  It is re-use which drives all 
>the
> other perceived benefits of using OO in any form.
>   
> To that end, we try to make our OO app as machine-independent on the client 
>as 
> possible.  Why bother designing all those classes, etc. only to have to 
>re-write the 
> blasted things so they run on another client platform?  Likewise, what's the 
>point 
> writing an awesome OO system that can't talk to another server platform 
>without 
> a re-write?  In each case, we lose our prime goal of code re-use.

I must differ. Code re-use is not _the_ end goal. It is a major part of OO,
but I think it's important to realize that component re-use is really what
you are after. I am sure you know this, but your comment didn't make it very
clear.

Using OO programming techniques you can develop and debug a component.
Whether this component is an employee record or an AP sub-system. By using
this component for all references of that object type, you re-use the code,
and all the other work in developing it. 

But this brings us to the part of your statement that I REALLY disagree with.
OO programming has nothing whatsoever to do with platform independence.
Smalltalk is OO, so is C++. Both of these languages have a much, much longer
history than Java and can be very effective tools for OO programming. Both
must be recompiled if the application is moved to another platform. 

Platform independance is an advantage of Java. It has nothing to do with the
language being OO, but rather that it runs in a Virtual Machine. 

To make a client "server independant", which seems to be what you are
describing, the client should be object based and refer to it's server using
a object model standard. But a "server independant" client can be written in
assembly code on a 6502 with no hopes of porting it to any other client
machine.

Obviously, the best combination would be a platform independant client
written in an OO language that addresses a CORBA standard interface. Say, a
Java client talking to a DSOM Java server object. 

> This idea of platform-specific client code goes against the grain of OO
> design, but I'm sure that they're out there...

I would imagine that the largest amount of OO programs in existance are
platform specific. But I do know that there is a lot of work being done both
object based, and platform independant. 

Probably all this is is a little semantic confusion. Often, though, people
new to OO programming and object based systems get thrown off course by these
semantic differences and so I think it's important to be clear. 

> Buck Calabro
 

Chris Rehm
Mr.AS400@ibm.net

How often can you afford to be unexpectedly out of business?
Get an AS/400.
root
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