使用 Tornado 和 Prototype 进行异步 COMET 查询

发布于 2024-08-22 19:04:33 字数 2784 浏览 10 评论 0原文

我正在尝试使用 Tornado 和 JS Prototype 库编写简单的 Web 应用程序。因此，客户端可以在服务器上执行长时间运行的作业。我希望这项工作异步运行 - 以便其他客户端可以查看页面并在那里做一些事情。

这是我得到的：

#!/usr/bin/env/ python

import tornado.httpserver
import tornado.ioloop
import tornado.options
import tornado.web
from tornado.options import define, options

import os
import string
from time import sleep
from datetime import datetime

define("port", default=8888, help="run on the given port", type=int)

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.render("templates/index.html", title="::Log watcher::", c_time=datetime.now())

class LongHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    def get(self):
        self.wait_for_smth(callback=self.async_callback(self.on_finish))
        print("Exiting from async.")
        return

    def wait_for_smth(self, callback):
        t=0
        while (t < 10):
            print "Sleeping 2 second, t={0}".format(t)
            sleep(2)
            t += 1
        callback()

    def on_finish(self):
        print ("inside finish")
        self.write("Long running job complete")
        self.finish()



def main():
    tornado.options.parse_command_line()

    settings = {
        "static_path": os.path.join(os.path.dirname(__file__), "static"),
        }

    application = tornado.web.Application([
        (r"/", MainHandler),
        (r"/longPolling", LongHandler)
        ], **settings
    )
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(options.port)
    tornado.ioloop.IOLoop.instance().start()


if __name__ == "__main__":
    main()

这是服务器部分。它有主视图（显示很少的问候语、当前服务器时间和 ajax 查询的 url，执行长时间运行的作业。如果按下按钮，则会执行长时间运行的作业。服务器挂起:( 我无法查看任何页面，而该作业正在运行。这是模板页面：

<html>
<head>
    <title>{{ title }}</title>

    <script type="text/javascript" language="JavaScript" src="{{ static_url("js/prototype.js")}}"></script>


    <script type='text/javascript' language='JavaScript'>
        offset=0
        last_read=0

        function test(){
            new Ajax.Request("http://172.22.22.22:8888/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

        
    </script>
</head>
<body>
    Current time is {{c_time}}
    <br>
    <input type="button" value="Test" onclick="test();"/>
</body>
</html>

我做错了什么？如何使用Tornado和Prototype（或jQuery）实现长池

PS：我已经看过Chat示例，但它太复杂了。无法理解它是如何工作的:(

PSS 下载完整的示例

原文

I'm trying to write simple web application using Tornado and JS Prototype library. So, the client can execute long running job on server. I wish, that this job runs Asynchronously - so that others clients could view page and do some stuff there.

Here's what I've got:

#!/usr/bin/env/ python

import tornado.httpserver
import tornado.ioloop
import tornado.options
import tornado.web
from tornado.options import define, options

import os
import string
from time import sleep
from datetime import datetime

define("port", default=8888, help="run on the given port", type=int)

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.render("templates/index.html", title="::Log watcher::", c_time=datetime.now())

class LongHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    def get(self):
        self.wait_for_smth(callback=self.async_callback(self.on_finish))
        print("Exiting from async.")
        return

    def wait_for_smth(self, callback):
        t=0
        while (t < 10):
            print "Sleeping 2 second, t={0}".format(t)
            sleep(2)
            t += 1
        callback()

    def on_finish(self):
        print ("inside finish")
        self.write("Long running job complete")
        self.finish()



def main():
    tornado.options.parse_command_line()

    settings = {
        "static_path": os.path.join(os.path.dirname(__file__), "static"),
        }

    application = tornado.web.Application([
        (r"/", MainHandler),
        (r"/longPolling", LongHandler)
        ], **settings
    )
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(options.port)
    tornado.ioloop.IOLoop.instance().start()


if __name__ == "__main__":
    main()

This is server part. It has main view (shows little greeting, current server time and url for ajax query, that executes long running job. If you press a button, a long running job executes. And server hangs :( I can't view no pages, while this job is running.
Here is template page:

<html>
<head>
    <title>{{ title }}</title>

    <script type="text/javascript" language="JavaScript" src="{{ static_url("js/prototype.js")}}"></script>


    <script type='text/javascript' language='JavaScript'>
        offset=0
        last_read=0

        function test(){
            new Ajax.Request("http://172.22.22.22:8888/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

        
    </script>
</head>
<body>
    Current time is {{c_time}}
    <br>
    <input type="button" value="Test" onclick="test();"/>
</body>
</html>

what am I doing wrong? How can implement long pooling, using Tornado and Prototype (or jQuery)

PS: I have looked at Chat example, but it too complicated. Can't understand how it works :(

PSS Download full example

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

浊酒尽余欢 2024-08-29 19:04:33

Tornado 是单线程 Web 服务器。 wait_for_smith 方法中的 while 循环正在阻止 Tornado。

您可以像这样重写该方法：

def wait_for_smth(self, callback, t=10):
    if t:
        print "Sleeping 2 second, t=%s" % t
        tornado.ioloop.IOLoop.instance().add_timeout(time.time() + 2, lambda: self.wait_for_smth(callback, t-1))
    else:
        callback()

您需要在顶部添加导入时间才能使其工作。

Tornado is single-threaded web server. Your while loop in wait_for_smith method is blocking Tornado.

You can rewrite that method like this:

def wait_for_smth(self, callback, t=10):
    if t:
        print "Sleeping 2 second, t=%s" % t
        tornado.ioloop.IOLoop.instance().add_timeout(time.time() + 2, lambda: self.wait_for_smth(callback, t-1))
    else:
        callback()

You need to add import time at the top to make this work.

回复收藏 0 原文

没企图 2024-08-29 19:04:33

function test(){
            new Ajax.Request("http://172.22.22.22:8888/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

应该是

function test(){
            new Ajax.Request("/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

function test(){
            new Ajax.Request("http://172.22.22.22:8888/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

should be

function test(){
            new Ajax.Request("/longPolling",
            {
                method:"get",
                asynchronous:true,
                onSuccess: function (transport){
                    alert(transport.responseText);
                }
            })
        }

回复收藏 0 原文

小傻瓜 2024-08-29 19:04:33

我已将 Tornado 的聊天示例转换为在 gevent 上运行。观看此处的现场演示和这里的解释和源代码。

它使用轻量级用户级线程（greenlet）并且速度相当/ Tornado 的内存使用。然而，代码很简单，您可以在处理程序中调用 sleep() 和 urlopen() 而不会阻塞整个进程，并且您可以生成执行相同操作的长时间运行的作业。在底层，应用程序是异步的，由用 C 编写的事件循环提供支持 (libevent ）。

您可以在此处阅读简介。