将Kotlin编译为JavaScript(Compile Kotlin to JavaScript)

 Facebook的做法非常有趣。 
 
 执行此类通知的常见方法是在给定的间隔（可能每隔几秒钟）轮询服务器上的脚本（使用AJAX），以检查是否发生了某些事情。 然而，这可能是网络密集型的，你经常做出无意义的请求，因为没有发生任何事情。 
 
 Facebook的方式是使用彗星方法，而不是轮询一个间隔，一旦一个投票完成，它发出另一个。 但是，对服务器上的脚本的每个请求都有非常长的超时，服务器只有在发生事件时才响应该请求。 如果您在Facebook上启动了Firebug的“控制台”选项卡，则可能会发现这一点，请求脚本可能需要几分钟。 这是非常巧妙的，因为这种方法会立即减少请求的数量，以及发送数量的频率。 您现在有一个事件框架可以让服务器“触发”事件。 
 
 在这之后，根据这些民意测验返回的实际内容，这是一个JSON响应，似乎是一个事件列表，以及有关它们的信息。 尽管如此，还是有点难看。 
 
 在实际的技术方面，AJAX是通往这里的方式，因为您可以控制请求超时等诸多事情。 我建议（Stack overflow cliche here）使用jQuery来做AJAX，它会占用很多交叉可兼容性的问题。 在PHP方面，您可以简单地轮询您的PHP脚本中的事件日志数据库表，只有在发生事件时才返回客户端？ 我期望有很多方法可以实现这一点。 
 
 实现： 
 
 服务器端： 
 
 在PHP中似乎有一些彗星库的实现，但是老实说，它真的很简单，这可能就像下面的伪代码一样： 
 
while(!has_event_happened()) {
   sleep(5);
}

echo json_encode(get_events());
 
 
 
 has_event_happened函数只会检查事件表或某些事件中是否发生过任何事情，然后get_events函数将返回表中新行的列表？ 取决于问题的上下文。 
 
 
 不要忘记更改您的PHP最大执行时间，否则会提前超时！ 
 
 
 客户端： 
 
 看看jQuery插件进行Comet交互： 
 
 
 
 项目主页： http : //plugins.jquery.com/project/Comet 
 
 
 Google代码： http : //code.google.com/p/jquerycomet/ - 看起来在subversion版本库中有一些示例用法。 
 
 
 也就是说，这个插件似乎增加了一些复杂性，在客户端上真的很简单，也许（和jQuery）一样： 
 
function doPoll() {
   $.get("events.php", {}, function(result) {
      $.each(result.events, function(event) { //iterate over the events
          //do something with your event
      });
      doPoll(); 
      //this effectively causes the poll to run again as
      //soon as the response comes back
   }, 'json'); 
}

$(document).ready(function() {
    $.ajaxSetup({
       timeout: 1000*60//set a global AJAX timeout of a minute
    });
    doPoll(); // do the first poll
});
 
 整个事情取决于你现有的架构如何组合在一起。 

The way Facebook does this is pretty interesting. 
 
A common method of doing such notifications is to poll a script on the server (using AJAX) on a given interval (perhaps every few seconds), to check if something has happened. However, this can be pretty network intensive, and you often make pointless requests, because nothing has happened.
 
The way Facebook does it is using the comet approach, rather than polling on an interval, as soon as one poll completes, it issues another one. However, each request to the script on the server has an extremely long timeout, and the server only responds to the request once something has happened. You can see this happening if you bring up Firebug's Console tab while on Facebook, with requests to a script possibly taking minutes. It is quite ingenious really, since this method cuts down immediately on both the number of requests, and how often you have to send them. You effectively now have an event framework that allows the server to 'fire' events.
 
Behind this, in terms of the actual content returned from those polls, it's a JSON response, with what appears to be a list of events, and info about them. It's minified though, so is a bit hard to read.
 
In terms of the actual technology, AJAX is the way to go here, because you can control request timeouts, and many other things. I'd recommend (Stack overflow cliche here) using jQuery to do the AJAX, it'll take a lot of the cross-compability problems away. In terms of PHP, you could simply poll an event log database table in your PHP script, and only return to the client when something happens? There are, I expect, many ways of implementing this.
 
Implementing:
 
Server Side:
 
There appear to be a few implementations of comet libraries in PHP, but to be honest, it really is very simple, something perhaps like the following pseudocode:
 
while(!has_event_happened()) {
   sleep(5);
}

echo json_encode(get_events());
 
 
 
The has_event_happened function would just check if anything had happened in an events table or something, and then the get_events function would return a list of the new rows in the table? Depends on the context of the problem really.
 
 
Don't forget to change your PHP max execution time, otherwise it will timeout early!
 
 
Client Side:
 
Take a look at the jQuery plugin for doing Comet interaction:
 
 
 
Project homepage: http://plugins.jquery.com/project/Comet
 
 
Google Code: https://code.google.com/archive/p/jquerycomet/ - Appears to have some sort of example usage in the subversion repository.
 
 
That said, the plugin seems to add a fair bit of complexity, it really is very simple on the client, perhaps (with jQuery) something like:
 
function doPoll() {
   $.get("events.php", {}, function(result) {
      $.each(result.events, function(event) { //iterate over the events
          //do something with your event
      });
      doPoll(); 
      //this effectively causes the poll to run again as
      //soon as the response comes back
   }, 'json'); 
}

$(document).ready(function() {
    $.ajaxSetup({
       timeout: 1000*60//set a global AJAX timeout of a minute
    });
    doPoll(); // do the first poll
});
 
The whole thing depends a lot on how your existing architecture is put together.