Sound like very complicated, can u come up something really simple? On Wednesday, January 22, 2014 1:42:09 PM UTC+11, Peter Donald wrote: > > Hi, > > I don't think there is a universal solution to this it comes down to > the capabilities of the browsers that are connecting to the site and > how you want to trade off timeliness versus server cost. In terms of > pushing to the client I would tend to use one of four techniques. > > * Polling: Check every time period N. > * Long Polling: Start poll but suspend the request and have server > respond when needed. > * SSE (aka Server Sent Events): Client opens connection and server > sends events to message as needed (also handles automagic > reconnection, and routing messages on client-side) > * WebSockets: Client opens connection to server, bi-directional > communication. > > It seems like what you probable want is SSE if available in the > browser and then fall back to polling strategy. In terms of what it > looks like in GWT you can check out the gwt-eventsource [1] library. > See [2] for some example code for the client and server (using jersey > jaxrs). If you want to use web sockets you can check out the > gwt-websockets [3] library and corresponding example code at [4]. > > Holler if you have any problems. Just note that I was working on > gwt-eventsource this morning and only just released it to Maven > Central an hour ago so you may need to wait a couple some time before > the main repository has synchronized the release. > > [1] https://github.com/realityforge/gwt-eventsource > [2] > https://github.com/realityforge/gwt-eventsource-example/tree/master/src/main/java/org/realityforge/gwt/eventsource/example > > [3] https://github.com/realityforge/gwt-websockets > [4] > https://github.com/realityforge/gwt-websockets-example/tree/master/src/main/java/org/realityforge/gwt/websockets/example > > > On Wed, Jan 22, 2014 at 12:48 PM, Tom <[email protected] <javascript:>> > wrote: > > Ok, I got a message system, user can send message to each other at any > time. > > The message icon is in the header. I want to program so that when person > A > > sends a message to person B, then B can be able to see the message in > the > > header immediately & automatically without needing to refresh the page. > > > > How does that system work? > > > > I think there some solutions here, > > > > -Solution1: we program so that each active page will check the message > every > > 5 minutes. This is not too smart since if there's no message, the server > > still receives the call every 5 min. Imagine there is a million users & > if > > each user opens the page & lives the page for the whole day then server > will > > receive too many unnecessary calls. > > > > -Solution2: Do some sort of global variable that check the incoming > message. > > When A sends message to B, the global variable will be changed, & we > needs > > to do something so that that variable can check all the active pages > that > > user B is opening & the system sends the reminder to all those pages. I > am > > not sure if this is the right way to do. > > > > Can you find a better solution? > > > > Does anyone know what is the wright way to build this system? > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "Google Web Toolkit" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To post to this group, send email to > > [email protected]<javascript:>. > > > Visit this group at http://groups.google.com/group/google-web-toolkit. > > For more options, visit https://groups.google.com/groups/opt_out. > > > > -- > Cheers, > > Peter Donald >
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