Interesting question: Web Server able to raise events?

[Nucleus]

This is the senario.... over the internet. Just say that I have 4 clients that are looking at a database table and one of them updates a record. Well, I need to automatically update the data in all of the clients without the clients specifically requesting the update. Is this possible?

Essentially asking if it is possible for a webserver to raise events in all connected clients?

[hellswraith]

Aren't there server side cursors that do that?

[Nucleus]

hmmm, not sure if they work with web services.... looking into it now.

[Lethal]

You could always create a seperate thread that will continuously poll a database for changes and re-paint the UI when needed. If you are using web services, I dont believe the answer (server-side cursor) above will work for you.

[Nucleus]

hmm looks like you can maintain a server side recordset in the middle tier but passing on the changes to the client in this case the consumer of the web service seems to be the challenge.

I am creating a client to consume the web service so I have complete control over the client, unlike a browser consuming the service, so I should be able to make a closer coupling between the client and the webserver.

Thinking about it, it may be possible to somehow get the client to subscribe for the information, then keep track of the ip address and the page (data) the client is currently viewing and to pass updates back to the client. When the app is closed, it automatically unsubscribes from the server, and if the client falls over, then a page can only be subscribed to for 24hrs max.

I wonder if this will be possible to implement?

[Nucleus]

Originally posted by Lethal
You could always create a seperate thread that will continuously poll a database for changes and re-paint the UI when needed. If you are using web services, I dont believe the answer (server-side cursor) above will work for you.

Yeah, that is how most "live data" comes through, but in my case I can't have any sort of time delay, it has to be a server side push rather than a client side poll. I know this isn't how the internet was made being a loosely coupled network, but using the http chanel gets around firewalls which is great as many orgs won't open up a port for your app due to security concerns and the data must be live. So I am looking for a way around the limitations.

Although I should probably look at getting a client side poll happening to see what the performance is like.