~justin-fathomdb/nova/justinsb-openstack-api-volumes

<?xml version="1.0" encoding="utf-8"?><!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.0 Transitional//EN' 'http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd'><html lang="en" xmlns="http://www.w3.org/1999/xhtml">

<head>

<title>Twisted Documentation: Generating a Page Dynamically</title>

</head>

<h1 class="title">Generating a Page Dynamically</h1>

The goal of this example is to show you how to dynamically generate the

contents of a page.

Taking care of some of the necessary imports first, we'll import <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.web.server.Site.html" title="twisted.web.server.Site">Site</a></code> and the <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.internet.reactor.html" title="twisted.internet.reactor">reactor</a></code>:

<pre class="python">1

from twisted.internet import reactor

from twisted.web.server import Site

</pre>

The Site is a factory which associates a listening port with the HTTP

protocol implementation. The reactor is the main loop that drives any Twisted

application; we'll use it to actually create the listening port in a moment.

Next, we'll import one more thing from Twisted Web: <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.web.resource.Resource.html" title="twisted.web.resource.Resource">Resource</a></code>. An instance of

<code>Resource</code> (or a subclass) represents a page (technically, the entity

addressed by a URI).

<pre class="python">1

from twisted.web.resource import Resource

</pre>

Since we're going to make the demo resource a clock, we'll also import the

time module:

<pre class="python">1

import time

</pre>

With imports taken care of, the next step is to define a

<code>Resource</code> subclass which has the dynamic rendering behavior we

want. Here's a resource which generates a page giving the time:

<pre class="python">1

class ClockPage(Resource):

isLeaf = True

def render_GET(self, request):

return "%s" % (time.ctime(),)

</pre>

Setting <code>isLeaf</code> to <code>True</code> indicates that

<code>ClockPage</code> resources will never have any children.

The <code>render_GET</code> method here will be called whenever the URI we

hook this resource up to is requested with the <code>GET</code> method. The byte

string it returns is what will be sent to the browser.

With the resource defined, we can create a <code>Site</code> from it:

<pre class="python">1

resource = ClockPage()

factory = Site(resource)

</pre>

Just as with the previous static content example, this configuration puts our

resource at the very top of the URI hierarchy, ie at <code>/</code>. With that

<code>Site</code> instance, we can tell the reactor to <a href="../../../core/howto/servers.html" shape="rect">create a TCP server</a> and start

servicing requests:

<pre class="python">1

reactor.listenTCP(8880, factory)

reactor.run()

</pre>

Here's the code with no interruptions:

<pre class="python"> 1

100

101

from twisted.web.resource import Resource

102

import time

103

104

class ClockPage(Resource):

105

isLeaf = True

106

def render_GET(self, request):

107

return "%s" % (time.ctime(),)

108

109

resource = ClockPage()

110

factory = Site(resource)

111

reactor.listenTCP(8880, factory)

112

reactor.run()

113

</pre>

114

115

</div>

116

117

<a href="../index.html">Index</a>

118

Version: 10.0.0

119

</body>

120

</html>

b'\\ No newline at end of file'

Older »