Robert Sartin <[EMAIL PROTECTED]> wrote:
>--- Filippos Slavik <[EMAIL PROTECTED]> wrote:
>> > another HTML-SERVLETS-JDBC-ODBC-DBMS as another.
>> None of the above approach belongs to the three tier architecture. In
>> both cases you have a client (java client or java servlet [ about the
>> seconds approach, the servlet, it can be somehow considered as a
>> three tier approach, but this is another story : ])
>
>I think this is an overly strict definition of "three tier". In particular,
I
>have trouble characterizing a servlet as a client. The HTML browser is a
razor
>thin client with absolutely no business logic at all (though you could
throw
>some in with JavaScript) and only presentation via a presentation facade in
the
>application layer. The servlet makes a great location for business logic
and
>allows for a data layer. You really don't have to use "three tier
middleware"
>to get a three tier system.
If you consider the servlet part of the business layer and not part of the
presentation layer, then that means your business layer is sending HTML to
the presentation layer. HTML is purely for presentation, is it not? Why is
it being generated in your business layer?
I think of it this way: how do I chop up the application such that I can (if
I ever need to) completely replace the presentation layer and/or completely
replace the data storage layer?
Let's pretend that for some reason, there is a requirement for some users to
access your system via a native MS Windows application. If your business
layer sends out HTML and expects HTML form input, it would be very hard.
However, if your business layer sends out business objects and expects the
same in return, then your new app can get those objects and display them as
it sees fit.
That's how I see it all, anway.
Erik
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