The splits between tiers don't have to be physical. RMI allows for the
*middle* tier to be distributed.
I feel your methodology is in the right direction.
I'm using HTML and Shockwave on the client. Servlets calling Business
classes on the middle tier ... and a Database server on the third tier.
> -----Original Message-----
> From: Prashant Mavinkurve [SMTP:[EMAIL PROTECTED]]
> Sent: Monday, March 08, 1999 11:37 AM
> To: [EMAIL PROTECTED]
> Subject: Re: 3-tier architecture and Servlets
>
> Hello,
> If I have a 3 tier architecture:
> First TIER (THE APPLET):
>
> - GUI.java (GUI elements)
> - ClientManager.java (Builds the select and update queries) and
> calls the RMI function. Works on the RETURN values of the RMI
> server.
>
> SECOND TIER:
> ------------
> - RMIserver, running on the WebServer. (Executes the
> query using JDBC) and returns the results as an
> object to the ClientManager.
>
> THIRD TIER:
> -----------
> - JDBC/Database with select etc...
>
> Is this a good way to design ?
>
> OR is it best to have the business logic in the RMI server and not
> the
> Applet area.
> Any help is appreciated.
> Thanks a lot,
> - Prashant
>
>
>
> "Kito D. Mann" wrote:
> >
> > > There's lots of different possible architectures, but I like to see it
> a bit
> > > differently from how you wrote it:
> > >
> > > Database: A database. :) Typical interface: "SELECT ...".
> > >
> > > Middle Tier: An RMI or CORBA server. Typical interface:
> "performOperation(...) or
> > > getDomainObject(...)".
> > >
> > > Client: An applet, that connects via RMI/CORBA/XML-RPC, etc. Typical
> interface:
> > > GUI.
> > >
> > > Alternate Client: Servlet, that generates HTML and manages state w/
> impovershed
> > > GUI environment (ie: web browsers)
> > >
> > > So, I see servlets as simply another type of clients. These servlets
> would connect
> > > to the true middle tier with some distributed object protocol. What
> I'm
> > > describing, though, is just one possibility.
> >
> > I like this setup as well, but in a lot cases the "Middle Tier" ends up
> garbled with
> > the "Alternate Client"/servlet (we'll pretend that no one _ever_ puts
> business logic in
> > the applet <grin>). Unfortunately, all projects aren't perfectly
> designed, and everyone
> > doesn't take the time to deal with RMI or CORBA. It's not a perfect
> world. What we're
> > really talking about here is the whole "N-Tier" concept. Several
> different layers
> > performing different functions -- theoretically the number can be
> expanded or
> > contracted as needed (for instance, if you have your business logic
> separated logically
> > within a servlet, it's quite easy to move it out of the servlet and into
> an RMI or
> > CORBA server, when the time/need arises).
> >
> > Just my two cents.
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Kito D. Mann
> > [EMAIL PROTECTED]
> > Virtua Communications Corp
> >
> >
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