When working on synchronous mode ,I think if no event occurs, the
application shoud stop at isc_wait_for_event() and suspend. After an
event occurs, the application then continues running.


isc_wait_for_event();
// stop here, dont'return until any event notifications arrive.

printf("I'm here! \n");




--- In firebird-support@yahoogroups.com, Helen Borrie <helebor@...>
wrote:

>
> At 05:01 PM 11/03/2006, you wrote:
> >Helen Borrie ,
> >
> >Thank you.
> >
> >
> >Here is from borland:
> >....
> >As soon as the application uses the API isc_wait_for_event() or

ESQL

> >statement EXEC SQL EVENT WAIT, the application is put to sleep

until

> >the event is posted.
> >...
> >
> >But my application can't be put to sleep at all .
>
> Hey, I didn't write the Borland documentation! :-)
>
> It should have been written as "the interface part of the

application

> is put to sleep until..."
>
> What it also leaves you to work out for yourself is that an
> application logically cannot wait for a synchronous event that it
> initiates for itself (the archetypal chicken-and-egg situation!).
>
> Consider it:
>
> 1) Set up the EPB
> 2) Register interest with isc_wait_for_event (or exec sql event

wait)

>
> But now the interface is "sleeping", so you cannot make any more
> function calls until the event returns. But the event will never
> return because you can't make any calls to execute the stored
> procedure or trigger in which you have planned for the event to

occur.

>
> If you want your application to receive notifications for its own
> events, then of course you must use asynchronous events.
>
> While there are some application scenarios where an application

might

> want to receive notifications for its own events, in most cases it

is

> not wanted. The application knows what it asked the server to
> do. The application is responsible for starting and committing

the

> work that it requests. It does not need an event to inform it

that

> the server did what it was asked to do. Transactions are
> atomic, meaning that they either do everything or they do none of
> it. Events tell applications about things that they would not
> otherwise know about.
>
> ./heLen
>