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I'm trying to find an example to show where data is sent from a server and is pushed to a/multiple clients which are updated immediately, i.e. the client doesn't make requests for updates. It doesn't matter whether we're talking mobile, desktop or whatever. An even better example would be where there were multiple recipients for the same message. It doesn't matter what the data is or the context it's used in, only the immediacy of receiving it. I was thinking that there might be some example in finance and the stock markets, but I haven't been able to find any through googling.

IM clients are a great example of this and are on my list of one ;)

If anyone works on applications of this nature or knows of particular implementations, can you give me a quick run down of the use case and if it's commercial software the name of the software.

This is all basically for research purposes so doesn't have to be particularly detailed.

If anyone can help, thanks.

EDIT - Granted the question is vague. Doing some concepting so need some examples. There must be a huge amount of apps that work like this.

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Obviously "immediate" is never going to happen..... light-speed, sir ;D Your question is a little vague though, could you maybe help describe a little more what you want, or why you need this? I can name a million things that act in that way, from skype, ts. ventrilo etic, to IM, submitting a webform, clicking a "download" link (have you ever waited more than a half second for it to start downloading?). –  Dmatig May 12 '10 at 9:43
    
@Dmatig. Well certainly not imediately as in lightspeed :P. But IM and skype are the type of things I'm after as the server sends information and the clients recieve it instantly. I suppose, what i'm really after is examples where a message can be sent from a server and clients are pushed the data. Browsers don't work that way as the user must make requests for the data. Will update my question to reflect this. Cheers –  James Hay May 12 '10 at 9:52
    
too vague a scenario. by your description, a centralised game server fits the bill. All gamers (client machines) connected to the server will receive game event data "immediately" as they play the game. –  icelava May 12 '10 at 9:55
    
@icelava Thats the kind of stuff I'm after. It's a vauge question because all I want is vague answers. I'm in the process of doing some concepting so want some examples to show –  James Hay May 12 '10 at 9:58
    
You should change this question to Community wiki - it's not a question that can be "answered" as a true solution - too open for discussion. –  icelava May 12 '10 at 10:03
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6 Answers

Internet Relay Chat (IRC)

as people are constantly pumping chat messages and events to the server (channel), everybody else connected gets updated.

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Server-based network games

Any game that connects to centralised server for real-time gaming, requires server to feed game event data to client gamers.

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The screen command in linux can have multiple screen attached to one session. So a change in one is pushed to all the others.

The

  nc 

command might also be useful, as far as I know it doesn't support connections from multiple clients, but it is a simple example.

In the programming world the observer pattern is probably what you want.

http://en.wikipedia.org/wiki/Observer_pattern

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From commercial point of view you can be interested in this product. It uses the push technology where data is pushed from the server and displayed on the client terminal.

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The wikipedia article Push technology can be a great starting point:

Synchronous conferencing and instant messaging are typical examples of push services. Chat messages and sometimes files are pushed to the user as soon as they are received by the messaging service. Both decentralised peer-to-peer programs (such as WASTE) and centralised programs (such as IRC or XMPP) allow pushing files, which means the sender initiates the data transfer rather than the recipient.

Email is also a push system: the SMTP protocol on which it is based is a push protocol (see Push e-mail). However, the last step —from mail server to desktop computer— typically uses a pull protocol like POP3 or IMAP. Modern e-mail clients make this step seem instantaneous by repeatedly polling the mail server, frequently checking it for new mail. The IMAP protocol includes the IDLE command, which allows the server to tell the client when new messages arrive. The original BlackBerry was the first popular example of push technology for email in a wireless context.

Another popular type of Internet push technology was PointCast Network, which gained popularity in the 1990s. It delivered news and stock market data. Both Netscape and Microsoft integrated it into their software at the height of the browser wars, but it later faded away and was replaced in the 2000s with RSS (a pull technology).

Other uses are push enabled web applications including market data distribution (stock tickers), online chat/messaging systems (webchat), auctions, online betting and gaming, sport results, monitoring consoles and sensor network monitoring.

The above article contains many links which I haven't duplicated here.

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StackExchange itself does this when it notifies users that new responses have been posted as they're editing their own response.

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