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

[Michael Van Canneyt]

On Sun, 3 Jun 2007, John Coppens wrote:

> On Sun, 3 Jun 2007 16:55:23 +0200 (CEST)
> Michael Van Canneyt <michael at freepascal.org> wrote:
> 
> > > 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.
> 
> If using the HTTP protocol, it's possible to define a refresh time of x
> seconds using a meta-tag:
> 
> <META HTTP-EQUIV="refresh"
>    CONTENT="3;URL='http://www.homepage.com/spot3.html'">
> 
> This is quite popular with webcams and such. But this is of course not
> the definition of a timeout value, you would have to know when the next
> value is due.

Yes,  but:

1. This is HTML, not HTTP. SOAP doesn't use HTML, it uses XML.
2. Even so, it's up to the client to actually implement the refresh. 
   A browser will do this, but a simple RPC mechanism usually will not. 
   (especially since it doesn't understand HTML)

Michael.