Steve,

> I need to handle that too at some stage so I'd be interested in what you come up with.

Sure, I'll keep you informed.

Uli

John,

> I guess the main problem is that anything "data dependent" in the
> application becomes invalid in this situation.  After trying the automatic
> reconnect (in DBISAM admittedly) I found it was easier and more consistent
> to restart the application.

Right.
Though a restart only makes sense if the connection can be established.
And another problem occurs if the application allows just one instance.
But that should be resolvable.

Uli

Uli

> Though a restart only makes sense if the connection can be established.

That's true.  I use this kind of process on unattended "kiosk type"
applications.  If a connection is not established at start up it shows an
appropriate display and just keeps retrying.

> And another problem occurs if the application allows just one instance.

Good point.  If one uses mutexes it would definitely need some kind of
sleep/retry to allow it to load.

John

Uli,

<< The reason of my question is, that I am looking for a way to react to a
disconnection. We talked about that in another thread.  My idea is like
that:

1. The application is disconnected
2. The application tries to reconnect and to reopen all tables and queries
that were opened before.
3. After a timeout it shuts down.

Sounds easy, seems to be difficult. >>

Do you want to deal with a situation where the remote session is *removed*
from the ElevateDB Server, or a situation where the remote session has
simply been disconnected ?  The latter situation (disconnect) is simple -
just make sure that a TEDBSession.OnRemoteReconnect event handler is
defined, and then make sure to set the Continue parameter to True.

http://www.elevatesoft.com/manual?action=viewevent&id=edb2&product=d&version=7&comp=TEDBSession&event=OnRemoteReconnect

--
Tim Young
Elevate Software
www.elevatesoft.com

Uli,

<< That's what I am doing now. I am using the OnRemoteReconnect event: >>

I should read ahead in these threads.

<< Both. In my case I have remote connections to some networks of my
clients. There are different applications (EDB-based) running on a number of
workstations there. Some of them are running unattended. In order to
exchange EDBServer e.g. I have to disconnect all sessions, install the
server and restart it. >>

Okay, so the sessions are being removed, not disconnected.

In that case:

1) Keep using the OnRemoteReconnect event, but set Continue to True, not
False like you're currently doing.  You basically want your application to
always try to reconnect to the ElevateDB Server at this point (see below 3)
for more modifications necessary).

2) Define a TApplication.OnException handler in your application, and trap
for error code #1107 (session ID XXX no longer exists on the server).  When
you see this error code, set a global Boolean variable to indicate that the
session is gone and set the remote TEDBSession.Connected property to False.

3) Modify your OnRemoteReconnect event handler to look at the global
variable that indicates that the session is gone.  If it sees this variable
is True, then set Continue to False and StopAsking to True.   If it sees
this variable as False, then set Continue to True.

4) Be sure to set the global variable to False in an
TEDBSession.AfterConnect event handler for your session:

http://www.elevatesoft.com/manual?action=viewevent&id=edb2&product=d&version=7&comp=TEDBSession&event=AfterConnect

That should do it.

--
Tim Young
Elevate Software
www.elevatesoft.com

Tim ,

> Do you want to deal with a situation where the remote session is
> *removed* from the ElevateDB Server, or a situation where the remote
> session has simply been disconnected ?

I want to handle both situations, but my question referred to *removed*.

Uli

Tim

> Okay, so the sessions are being removed, not disconnected.
>
> In that case:
....
> That should do it.

Thanks a lot for this detailed explanation. I'll try it exactly like this.

Uli

Hello Tim,

I tried exactly your way to handle the lost remote session, but in my application is the application.OnException event not fired?!?!? So I´m not able to set my global boolean variable to True
I can not find - why? Do you have any idea?

best regards
Michael

"Tim Young [Elevate Software]" wrote:

Uli,

<< That's what I am doing now. I am using the OnRemoteReconnect event: >>

I should read ahead in these threads.

<< Both. In my case I have remote connections to some networks of my
clients. There are different applications (EDB-based) running on a number of
workstations there. Some of them are running unattended. In order to
exchange EDBServer e.g. I have to disconnect all sessions, install the
server and restart it. >>

Okay, so the sessions are being removed, not disconnected.

In that case:

1) Keep using the OnRemoteReconnect event, but set Continue to True, not
False like you're currently doing.  You basically want your application to
always try to reconnect to the ElevateDB Server at this point (see below 3)
for more modifications necessary).

2) Define a TApplication.OnException handler in your application, and trap
for error code #1107 (session ID XXX no longer exists on the server).  When
you see this error code, set a global Boolean variable to indicate that the
session is gone and set the remote TEDBSession.Connected property to False.

3) Modify your OnRemoteReconnect event handler to look at the global
variable that indicates that the session is gone.  If it sees this variable
is True, then set Continue to False and StopAsking to True.   If it sees
this variable as False, then set Continue to True.

4) Be sure to set the global variable to False in an
TEDBSession.AfterConnect event handler for your session:

http://www.elevatesoft.com/manual?action=viewevent&id=edb2&product=d&version=7&comp=TEDBSession&event=AfterConnect

That should do it.

--
Tim Young
Elevate Software
www.elevatesoft.com

Michael,

<< I tried exactly your way to handle the lost remote session, but in my
application is the application.OnException event not fired?!?!? So I´m not
able to set my global boolean variable to True I can not find - why? Do you
have any idea? >>

When you run it in the debugger, is the exception raised ?  If so, then
trace it through and see if you're trapping the exception earlier in the
call stack.

--
Tim Young
Elevate Software
www.elevatesoft.com

<<Okay, so the sessions are being removed, not disconnected.

In that case:

1) Keep using the OnRemoteReconnect event, but set Continue to True, not
False like you're currently doing.  You basically want your application to
always try to reconnect to the ElevateDB Server at this point (see below 3)
for more modifications necessary).

2) Define a TApplication.OnException handler in your application, and trap
for error code #1107 (session ID XXX no longer exists on the server).  When
you see this error code, set a global Boolean variable to indicate that the
session is gone and set the remote TEDBSession.Connected property to False.

3) Modify your OnRemoteReconnect event handler to look at the global
variable that indicates that the session is gone.  If it sees this variable
is True, then set Continue to False and StopAsking to True.   If it sees
this variable as False, then set Continue to True.

4) Be sure to set the global variable to False in an
TEDBSession.AfterConnect event handler for your session:

http://www.elevatesoft.com/manual?action=viewevent&id=edb2&product=d&version=7&comp=TEDBSession&event=AfterConnect

That should do it.
>>

Tim,

When I am in the debugger too long the session is being removed. So I thought I'd implement your suggestions and although the code does get executed, the session isn't being restarted. I know I can increase the server timeout, but I'd like to see this code working in case the client has a similar problem.

I must be missing something obvious in my code (see below), and I'm wondering if you (or someone else) can look it over. BTW, TdmMain is the Datamodule.

For instance, shouldn't the code be setting MySession.Connected := true; someplace so it creates the new session? After all, if the old session was lost on the server, don't I have to create a new session?

TIA
Barry


procedure TdmMain.cwSessionAfterConnect(Sender: TObject);
begin
 SessionGone := false;
end;


procedure TdmMain.cwSessionRemoteReconnect(Sender: TObject; var Continue,
 StopAsking: Boolean);
begin
 if SessionGone then
   begin
     Continue   := false;
     StopAsking := true;
   end
 else
   begin
     Continue := true;
   end;
end;

procedure TdmMain.AppException(Sender: TObject; E: Exception);
 begin
   if Assigned(E) then
     if (E is EDatabaseError) and (E is EEDBError) then
       begin
         if EEDBError(E).ErrorCode=EDB_Error_SessionNotFound then
           begin
             SessionGone         := true;
             MySession.Connected := false;
           end;
       end;
 end;

procedure TdmMain.DataModuleCreate(Sender: TObject);
begin
 SessionGone             := false;
 Forms.Application.OnException := AppException;
end;