CORBA vrs sockets is a tough one on the front of it, but the amount of
advantage that CORBA provides - platform and language neutrality mostly,
plus automatic failover, not to mention the 'cool' factor :) - is worth
it, IMO. If I had control over the client and the server, I'd go with a
higher level CORBA interface - its just so much easier! (and I can write
the server in Java, which I LOVE, and have it run on a nice, grunty Sun
box, or an NT box if money is tight :) )
Remember, and Annie will hate me for saying this, but Delphi's CORBA
stuff is licenced by the SERVER, not by the CLIENT (MIDAS is different,
I think?). Get a replacement ORB for Visi - and there are loads out
there for free - and your home free - or at whatever cost the ORB ends
up being. I haven't tried this - and I dont know of anyone who has - but
it SHOULD work, as they all use IIOP as the transport - thats exactly
the POINT of CORBA!!!
IMO, I'd go with Visi unless the cost was THE overriding factor -
remember, there are always three things wanted - good (ie, low) price,
on time, good (ie, high) quality. You can only ever have 2. :)
N
Tony Blomfield wrote:
>
> 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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> Website: http://www.delphi.org.nz
>
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