[fpc-pascal] Web Service Toolkit - Notify the Client

Michael Van Canneyt michael at freepascal.org
Sun Jun 3 16:55:23 CEST 2007

On Sun, 3 Jun 2007, Johann Glaser wrote:

> Hi!
> > > Usually the frontend does a remote procedure call to the backend. There
> > > is one important problem I'm facing now. I want the backend (service
> > > provider) to notify the frontend (service consumer) as soon as a new
> > > measurement value has arrived. So this is the reverse direction of
> > > communication.
> > > 
> > > Is this possible? Can you please point me to information how to
> > > accomplish this?
> > 
> > This is not possible in SOAP, unless you do continuous polling.
> Is it possible to delay a SOAP call a few seconds at the service
> provider (until new data is available)? Hmm, this reveals the question
> what are the timeouts for TCP/IP connection and for the web services? 

I think a few seconds are possible, a timeout is usually longer than
that. The webservices do not specify any values for timeouts. I'm not
sure whether the HTTP protocol has such definitions, but I would be 
surprised if it had.


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