Ajax Asynchronous refresh. Is it possible ?

Hi,
>
Say i have a server process which listens for some changes in database.
When a change occurs i want to refresh my page in browser by notyfinig it.
>
I do not want to refresh my page i.e. every 5 seconds, i just want to
refresh it ONLY on server change just like desktop applications do.
>
The problem is that refreshing evry n seconds has to much impact on my
web server. The refresh action should be taken only when something
really happens that makes sense
>
Is it possible ?
>
greets, peter
>

I dont think that is possible, you cant "notify" a web browser client that
something has changed on the server. That is the nature of web sites and web
applications, they are "stateless".
>
"Piotr Nowak" wrote:
>

Hi,
>
Say i have a server process which listens for some changes in database.
When a change occurs i want to refresh my page in browser by notyfinig it.
>
I do not want to refresh my page i.e. every 5 seconds, i just want to
refresh it ONLY on server change just like desktop applications do.
>
The problem is that refreshing evry n seconds has to much impact on my web
server. The refresh action should be taken only when something really
happens that makes sense
>
Is it possible ?
>
greets, peter

As long as there is some asp.net code you can run that will return a true or
false as to the server being updated then this is possible. Use an ajax
call every x seconds and when it returns true issue a page reload via
javascript.
>
"Piotr Nowak" <p.nowak2@STRIPTHISwasko.plwrote in message
news:fajeb8$ont$1@atlantis.news.tpi.pl...>
>

because every x second i would have to do a database hit to check if
something changed, then do a page refresh.
im not shure if i was enough clear..

Hi,
>
Say i have a server process which listens for some changes in database.
When a change occurs i want to refresh my page in browser by notyfinig it.
>
I do not want to refresh my page i.e. every 5 seconds, i just want to
refresh it ONLY on server change just like desktop applications do.
>
The problem is that refreshing evry n seconds has to much impact on my web
server. The refresh action should be taken only when something really
happens that makes sense
>
Is it possible ?
>
greets, peter

No the server can't reach a web client. This is always the client that sends
a request to the server and the server only responds to incoming requests.
>
You could issue an AJAX call to the server that just tell if the client
should be updated. If not you have nothing more to do, if yes you can issue
your more complex ajax calls that would update parts of your pages...
>
Youn may want to explain a bit more what you are trying to do...
--
Patrice
>
"Piotr Nowak" <p.nowak2@STRIPTHISwasko.pla écrit dans le message de news:
fajeb8$ont$1@atlantis.news.tpi.pl...>
>

Patrice pisze:Sure its quite generic problem.
>
Imagine you develop a online game, like ogame.
There's a lot action behind the scenes, players are making some actions
that take some time (training soldiers, building houses) which takes some
time (minutes, hours, even days). after time is up and soldier, building
is finished a browser should be refreshed to say - 'hey, your request is
done now !, you succesfully trained 5 soldiers and built one house'.
>
So, it doesnt make sense to poll every 5 seconds if action of building a
house last 2 days ! Divide 2days by 5 seconds and you get number of
waisted requests to check if action is done.
>
was this enough clear for You ?
>
best regards
>

Hi,
>
Say i have a server process which listens for some changes in database.
When a change occurs i want to refresh my page in browser by notyfinig it.
>
I do not want to refresh my page i.e. every 5 seconds, i just want to
refresh it ONLY on server change just like desktop applications do.
>
The problem is that refreshing evry n seconds has to much impact on my
web server. The refresh action should be taken only when something
really happens that makes sense
>
Is it possible ?
>
greets, peter