Board index » delphi » Some Theory

Some Theory


2005-08-22 07:02:53 PM
delphi91
D7. Arch.
I am building an app server based on a TRemoteDataModule a DataSetProvider
(dsp) and and ADO Table (atbl).
Wheh the Client Applies updates I am not seeing the correct data in my
Client Form after the update.
On the app server the SQL is being created correctly and the underlying
database table is undeed updated.
Q1: Whar mechanism (if any) updates the contents of the ADO table since the
SQL is directed to the database server.
Q2 Test I have carried seem to show thta the cds.Refresh returns data from
the ADO component and not the under;ying database table.. What keeos the
ADO component and the SAL server in sync?
Q3: What is the best way to monitor the SQL created in the dsp?
TIA
Ephraim
 
 

Re:Some Theory

Ephraim writes:
Quote
Q1: Whar mechanism (if any) updates the contents of the ADO table since the
SQL is directed to the database server.

You could use dsp.ResolveToDataSet=True, but it is not recommended
Quote
Q2 Test I have carried seem to show thta the cds.Refresh returns data from
the ADO component and not the under;ying database table.. What keeos the
ADO component and the SAL server in sync?

This gives unnecessary overhead to the system. The ADO components should
not keep state in case of a multi tier application. You should keep in
mind that all the benefits of using RemoteDatamodules (e.g. scalability)
can be achieved only if you keep the app server stateless
Quote
Q3: What is the best way to monitor the SQL created in the dsp?

Use TLogProvider.pas from midess open source project:
sourceforge.net/projects/midess/
Take a look at:
tinyurl.com/5frcw
and don't use TADOTable. Choose TADOQuery (or TADODataSet) instead.
When you use midas/datasnap with ADO you should decide to give full
update control to midas
Regards,
Kostas