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

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<title>Twisted Documentation: Static URL Dispatch</title>

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<h1 class="title">Static URL Dispatch</h1>

The goal of this example is to show you how to serve different content at

different URLs.

The key to understanding how different URLs are handled with the resource

APIs in Twisted Web is understanding that any URL can be used to address a node

in a tree. Resources in Twisted Web exist in such a tree, and a request for a

URL will be responded to by the resource which that URL addresses. The

addressing scheme considers only the path segments of the URL. Starting with the

root resource (the one used to construct the <code>Site</code>) and the first

path segment, a child resource is looked up. As long as there are more path

segments, this process is repeated using the result of the previous lookup and

the next path segment. For example, to handle a request for

<code>/foo/bar</code>, first the root's "<code>foo</code>" child is retrieved,

then that resource's "<code>bar</code>" child is retrieved, then that resource

is used to create the response.

With that out of the way, let's consider an example that can serve a few

different resources at a few different URLs.

First things first: we need to 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>, the factory for HTTP servers, <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>, a convenient base class

for custom pages, and <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.internet.reactor.html" title="twisted.internet.reactor">reactor</a></code>,

the object which implements the Twisted main loop. We'll also import <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.web.static.File.html" title="twisted.web.static.File">File</a></code> to use as the resource at one

of the example URLs.

<pre class="python">1

from twisted.web.server import Site

from twisted.web.resource import Resource

from twisted.internet import reactor

from twisted.web.static import File

</pre>

Now we create a resource which will correspond to the root of the URL

hierarchy: all URLs are children of this resource.

<pre class="python">1

root = Resource()

</pre>

Here comes the interesting part of this example. We're now going to create

three more resources and attach them to the three URLs <code>/foo</code>,

<code>/bar</code>, and <code>/baz</code>:

<pre class="python">1

root.putChild("foo", File("/tmp"))

root.putChild("bar", File("/lost+found"))

root.putChild("baz", File("/opt"))

</pre>

Last, all that's required is to create a <code>Site</code> with the root

resource, associate it with a listening server port, and start the reactor:

<pre class="python">1

factory = Site(root)

reactor.listenTCP(8880, factory)

reactor.run()

</pre>

With this server running, <code>http://localhost:8880/foo</code> will serve a

listing of files from <code>/tmp</code>, <code>http://localhost:8880/bar</code>

will serve a listing of files from <code>/lost+found</code>, and

<code>http://localhost:8880/baz</code> will serve a listing of files from

<code>/opt</code>.

Here's the whole example uninterrupted:

<pre class="python"> 1

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from twisted.web.static import File

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root = Resource()

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root.putChild("foo", File("/tmp"))

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factory = Site(root)

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reactor.listenTCP(8880, factory)

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reactor.run()

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</pre>

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

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Version: 10.0.0

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