[Lazarus] 3-tier database application

Michael Van Canneyt michael at freepascal.org
Wed Mar 19 13:48:10 CET 2008

On Wed, 19 Mar 2008, Graeme Geldenhuys wrote:

> Hi,
> Has anybody created a multi-tier (or 3-tier) database application with
> Lazarus? I'm looking for a solution that will work on Linux and
> Windows.
>       PC #1                           PC #2                      PC #3
> Client Application    ----->    Application Server    ----->   RDMS (db)
> In Delphi we used TClientDataset and midas.dll.  What options do we
> have for FPC and Lazarus?  Kylix 3 Enterprise used WebServices and
> SOAP, but I have never worked with WebServices or SOAP in my life.

You have no options currently. I have EXACTLY the same needs , and
believe me, I searched :-)

But: Joost van der sluis is working on TClientDataset support.
What is currently missing is the package writer (deltas). 
Local indexes, and filtering exists already. WST for FPC can 
take care of the package transport.

You can help him by porting hyperbase to FPC and then we should 
almost be there. (I think hyperbase, by vladimir gaitanoff, is the 
alternative to midas you refer to... It's free, but requires
vglib by the ame author, but vglib is not free. I have the sources,

Normally, I will start a Lazarus project real soon now
(or so I believe since some millenia ;-)), so I would be willing
to invest some company time in this myself. When I start this
project, I planned to add some other features to TDataset:
- Local filtering at the TDataset level.
- Built-in recoding support.
The plans for this are drawn, it's just a matter of implementing

Maybe we can cooperate a bit on this ?


> If WebServices are the only option, I would prefer to embed the HTTP
> server inside the Application Server tier, so I don't have to deploy
> Apache etc...  Not being stateless would also be a nice bonus (or at
> least some work-around for it like is done in Kylix)
> Anybody know of something like this?  I remember there was some single
> developer that wrote and alternative to Midas (for Delphi). I think he
> used Jedi's version control application as an example application.
> I'm not sure of the product name, what technologies he uses or if it
> is open-source. :-(
> Regards,
>   - Graeme -
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