Thanks.
That sounds pretty impressive. Are you using Corba or low level sockets?
Corba of course has the disadvantage that it boosts some one else's bank
account - probably to the detriment of mine. Is there a worthwhile margin in
using Corba?
-----Original Message-----
From: Kerry Sainsbury <[EMAIL PROTECTED]>
To: Multiple recipients of list delphi <[EMAIL PROTECTED]>
Date: Thursday, 2 September 1999 9:40 PM
Subject: Re: [DUG]: Thin Database Components.
On 2/09/99 at 20:16 Tony Blomfield wrote:
> By "Thin" I am referring
>to designing applications in such a way as to minimise the network traffic,
>Take a look at a telnet session into an AS400 as an example of
>"Thin" within this definition.
>I am not a three tier expert, but I find it
>hard to beleive that a three tiered object brokering approach can be an
>efficient model for slow networks
It depends how you're coding things (of course!).
Those telnet sessions are fairly network intensive too. *Every* keystroke is
sent individually across the network, interpretted by the AS400, and an
escape sequence sent back across the network instructing the telnet
application to update the screen to reflect the new-look screen.
Image I have a multi-tier system that handles the processing of an order.
The client tier is some simple HTML form. I click the 'submit button' and
information about the product code and quantity is sent to the middle tier.
The middle tier holds my business logic, and the database. It will need to:
- Checks my security, by hitting a number of database tables
- Checks my credit status, by hitting a number of database tables
- Creates a new order record, by inserting into a database table
- Creates an order detail record, by inserting into a database table
- Produces a picking-slip, by printing a bit of paper on a printer connected
to the server
- Updates sales analysis tables
- Lots more stuff, but you're getting the idea by now.
The only stuff that's gone across the network has been the product,
quantity, and (maybe) customer information. All that network traffic related
to SQL calls has all occured on the server. In a 2-tier setup, the SQL
statements would all have had to be sent up to the server (over the network)
and the results sent back down to the client (ditto).
The other beauty of an n-tier architecture is the reduction in required
resources, like database connections. In a 2 tier setup each client tends to
need its own connection. In an n-tier environment they're more likely to be
shared, so the server needs less memory, and you probably need to buy less
database licenses.
I'm sold on the idea.
Cheers,
Kerry S
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