Not sure if this is the forum to ask the following:

I've written a small app in Delphi 2010 that uses EDB and that works great. Now I am working on the exception processing so that mishaps are handled cleanly. The first item i wish to check is the availability of a connection to
my remote server. The way I do it now is by wraping a try ... except around the very first ExecSQL statement that
my program expects to encounter. If I get an exception it's probably because I have no connection and I
handle it with a message to the user followed by terminating the application.

This doesn't seem to be the neatest or best way to accomplish what I'm trying to do. What is suggested as
a proper way to check the availability of the server? Seems this should be checked even before attempting
to execute a query or any other SQL statement.

My program consists of one datamodule that holds an engine, a session, a database, and a query component, plus
one main form.

Thanks

Oliver

Oliver


I don't know about client/sever but in file/server I'd try opening the session or the database.

Roy Lambert

Oliver,

> This doesn't seem to be the neatest or best way to accomplish what I'm trying to do. What is suggested as
> a proper way to check the availability of the server? Seems this should be checked even before attempting
> to execute a query or any other SQL statement.

This is the code, I use in all my applications:

procedure Tdm.DataModuleCreate(Sender: TObject);
begin
  try
    MySession.Connected := true;
  except
    on E: Exception do
    begin
      if (E is EDatabaseError) and (E is EEDBError) then
      begin
        if (EEDBError(E).ErrorCode = EDB_ERROR_CLIENTCONN) then
        begin
          Application.MessageBox('No connection possible.',
Global.titel, 16);
          halt;
        end
        else
        begin
          Application.MessageBox(PChar('Database Error # ' +
IntToStr(EEDBError(E).ErrorCode)), Global.titel, 64);
          halt;
        end;
      end
      else
      begin
        Application.MessageBox('Unknown Database Error.', Global.titel,
16);
        halt;
      end;
    end;
  end;
end;

Oliver,

<< I've written a small app in Delphi 2010 that uses EDB and that works
great. Now I am working on the exception processing so that mishaps are
handled cleanly. The first item i wish to check is the availability of a
connection to my remote server. The way I do it now is by wraping a try ...
except around the very first ExecSQL statement that my program expects to
encounter. If I get an exception it's probably because I have no connection
and I handle it with a message to the user followed by terminating the
application.

This doesn't seem to be the neatest or best way to accomplish what I'm
trying to do. What is suggested as a proper way to check the availability of
the server? Seems this should be checked even before attempting to execute a
query or any other SQL statement. >>

I would have the TEDBSession try to connect via a special method added to
the data module (call it Initialize or something similar).  That way you can
control the connection process, including error trapping and possibly
retrying the connection if it fails.

--
Tim Young
Elevate Software
www.elevatesoft.com

Ulrich, thank you. I will study the code and adapt.

Oliver


Uli Becker wrote:

Oliver,

> This doesn't seem to be the neatest or best way to accomplish what I'm trying to do. What is suggested as
> a proper way to check the availability of the server? Seems this should be checked even before attempting
> to execute a query or any other SQL statement.

This is the code, I use in all my applications:

procedure Tdm.DataModuleCreate(Sender: TObject);
begin
  try
    MySession.Connected := true;
  except
    on E: Exception do
    begin
      if (E is EDatabaseError) and (E is EEDBError) then
      begin
        if (EEDBError(E).ErrorCode = EDB_ERROR_CLIENTCONN) then
        begin
          Application.MessageBox('No connection possible.',
Global.titel, 16);
          halt;
        end
        else
        begin
          Application.MessageBox(PChar('Database Error # ' +
IntToStr(EEDBError(E).ErrorCode)), Global.titel, 64);
          halt;
        end;
      end
      else
      begin
        Application.MessageBox('Unknown Database Error.', Global.titel,
16);
        halt;
      end;
    end;
  end;
end;