~ntt-pf-lab/nova/monkey_patch_notification

<?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: Web Application Development</title>

</head>

<h1 class="title">Web Application Development</h1>

<div class="toc"><ol><li><a href="#auto0">Code layout</a></li><li><a href="#auto1">Web application deployment</a></li><li><a href="#auto2">Understanding resource scripts (.rpy files)</a></li></ol></div>

<h2>Code layout<a name="auto0"/></h2>

The development of a Twisted Web application should be orthogonal to its

deployment. This means is that if you are developing a web application, it

should be a resource with children, and internal links. Some of the children

might use <a href="http://www.divmod.org/projects/nevow" shape="rect">Nevow</a>, some

might be resources manually using <code>.write</code>, and so on. Regardless,

the code should be in a Python module, or package, outside the web

tree.

You will probably want to test your application as you develop it. There are

many ways to test, including dropping an <code>.rpy</code> which looks

like:

<pre class="python">1

from mypackage import toplevel

resource = toplevel.Resource(file="foo/bar", color="blue")

</pre>

into a directory, and then running:

% twistd web --path=/directory

</pre>

You can also write a Python script like:

<pre class="python">1

#!/usr/bin/env python

from twisted.web import server

from twisted.internet import reactor

from mypackage import toplevel

reactor.listenTCP(8080,

server.Site(toplevel.Resource(file="foo/bar", color="blue")))

reactor.run()

</pre>

<h2>Web application deployment<a name="auto1"/></h2>

Which one of these development strategies you use is not terribly important,

since (and this is the important part) deployment is orthogonal.

Later, when you want users to actually use your code, you should worry

about what to do -- or rather, don't. Users may have widely different needs.

Some may want to run your code in a different process, so they'll use

distributed web (<code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.web.distrib.html" title="twisted.web.distrib">twisted.web.distrib</a></code>). Some may be

using the <code>twisted-web</code> Debian package, and will drop in:

% cat > /etc/local.d/99addmypackage.py

from mypackage import toplevel

default.putChild("mypackage", toplevel.Resource(file="foo/bar", color="blue"))

</pre>

If you want to be friendly to your users, you can supply many examples in

your package, like the above <code>.rpy</code> and the Debian-package drop-in.

But the ultimate friendliness is to write a useful resource which does

not have deployment assumptions built in.

<h2>Understanding resource scripts (<code>.rpy</code> files)<a name="auto2"/></h2>

Twisted Web is not PHP -- it has better tools for organizing code Python

modules and packages, so use them. In PHP, the only tool for organizing code is

a web page, which leads to silly things like PHP pages full of functions that

other pages import, and so on. If you were to write your code this way with

Twisted Web, you would do web development using many <code>.rpy</code> files,

all importing some Python module. This is a bad idea -- it mashes

deployment with development, and makes sure your users will be tied to

the file-system.

We have <code>.rpy</code>s because they are useful and necessary. But using

them incorrectly leads to horribly unmaintainable applications. The best way to

ensure you are using them correctly is to not use them at all, until you are on

your final deployment stages. You should then find your

<code>.rpy</code> files will be less than 10 lines, because you will not

have more than 10 lines to write.

100

101

</div>

102

103

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

104

Version: 10.0.0

105

</body>

106

</html>

b'\\ No newline at end of file'

Older »