用jQuery和PHP实现长轮询 [英] Implementing long-polling with jQuery and PHP

问题描述

我想基于JavaScript(jQuery将用于AJAX)和PHP建立聊天.

I want to build a chat, based on JavaScript (jQuery will be used for AJAX) and PHP.

我听说这样做的一个好方法是使用长轮询.

I've heard a good way of doing this is to use long-polling.

我确实知道这个主意，但是我不知道如何在服务器端实现它.

I do understand the idea, but I don't know how to implement it on the server side.

无限循环听起来是个坏主意.

An infinite loop sounds like a bad idea.

推荐答案

您不想创建无限循环，但是可以设置超时.基本上循环X秒等待某种数据，如果没有发生，则向客户端发送响应，告诉客户端它需要发起一个新请求，该请求具有相同的超时时间.

You don't want to create an infinite loop, but you can set a timeout. Basically loop for X second waiting for some sort of data, and if that doesn't happen send a response to the client telling it that it needs to initiate a new request, which will have the same timeout period.

$source; // some data source - db, etc
$data = null; // our return data
$timeout = 30; // timeout in seconds
$now = time(); // start time

// loop for $timeout seconds from $now until we get $data
while((time() - $now) < $timeout) {
    // fetch $data
    $data = $source->getData();

    // if we got $data, break the loop
    if (!empty($data)) break;

    // wait 1 sec to check for new $data
    usleep(10000);
}

// if there is no $data, tell the client to re-request (arbitrary status message)
if (empty($data)) $data = array('status'=>'no-data');

// send $data response to client
echo json_encode($data);

这篇关于用jQuery和PHP实现长轮询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！