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

[Vernon Hamberg <hambergv@xxxxxxxxxxxxxx>]

Hi, Buck

At 06:40 PM 12/1/1997 -0500, you wrote:

-snip-

>Oh, no!  I hope I didn't say that!  I want the client to ask for data and
for the
>server to provide it.  Chris and I have been talking about 2 different ways
>for the server to present data to the client:
>
>1.  Client sends request to a server program via data queue.
>     Server returns data to client via data queue.
>2.  Client sends "request" to server database via SQL (ODBC/JDBC...)
>     Server "returns" data to client via standard SQL.

This looks like what is sometimes called a 2-tier design, where data server
and database are on the same platform. Maybe look at a 3-tier design, where
the client asks a middleman for data services, including read & write and
validation. The middleman responds by getting the data from the backend,
applying edits & conversions, maybe, and returning the data(or an
indication the request was satisfied or not). That server could be a
separate box or simply a separate application. I've found it useful to
distinguish physical structure vs. logical structure in these things.

That way it's

1. Client to server pgm; server pgm to database via data queue (AS/400)
                       ; server pgm to database via ODBC (AS/400 or NT or ?)
                       ; server pgm to database via JDBC
                       ; server pgm to database via ? (UNIX?)

The server pgm, then, is the one that needs to know about the different
platforms, and this is where polymorphism could come into play.


Anyway, this has been really interesting and informative for me, too. I've
enjoyed the interchange. These ideas are, to some extent, very new to all
of us, I think. Although the thread seems to be winding down, the issues
will continue to raise their ugly heads.

BTW, there's a paper at IBM called "What's So Hot About Java?" Site is
<http://www.ibm.com/java/education/hotjava.html>. It discusses some basic
concepts, as well as provides some examples (couple typos—watch out).

Holiday cheers

Vernon Hamberg
Systems Software Programmer
Old Republic National Title Insurance Company
400 Second Avenue South
Minneapolis, MN  55401-2499
(612) 371-1111 x480


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