<?xml version="1.0"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" lang="en"><head><title>Twisted Documentation: Overview of Twisted Web</title><link href="../howto/stylesheet.css" type="text/css" rel="stylesheet" /></head><body bgcolor="white"><h1 class="title">Overview of Twisted Web</h1><div class="toc"><ol><li><a href="#auto0">Introduction</a></li><li><a href="#auto1">Twisted Web's Structure</a></li><li><a href="#auto2">Resources</a></li><li><a href="#auto3"> Web programming with Twisted Web </a></li></ol></div><div class="content"><span></span><h2>Introduction<a name="auto0"></a></h2><p>Twisted Web is a web application server written in pure Python, with APIs at multiple levels of abstraction to facilitate different kinds of web programming. </p><h2>Twisted Web's Structure<a name="auto1"></a></h2><p><img src="../img/web-overview.png" /></p><p>When the Web Server receives a request from a Client, it creates a Request object and passes it on to the Resource system. The Resource system dispatches to the appropriate Resource object based on what path was requested by the client. The Resource is asked to render itself, and the result is returned to the client.</p><h2>Resources<a name="auto2"></a></h2><p>Resources are the lowest-level abstraction for applications in the Twisted web server. Each Resource is a 1:1 mapping with a path that is requested: you can think of a Resource as a single <q>page</q> to be rendered. The interface for making Resources is very simple; they must have a method named <code>render</code> which takes a single argument, which is the Request object (an instance of <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.server.Request.html" title="twisted.web.server.Request">twisted.web.server.Request</a></code>). This render method must return a string, which will be returned to the web browser making the request. Alternatively, they can return a special constant, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.server.NOT_DONE_YET.html" title="twisted.web.server.NOT_DONE_YET">twisted.web.server.NOT_DONE_YET</a></code>, which tells the web server not to close the connection; you must then use <code class="python">request.write(data)</code> to render the page, and call <code class="python">request.finish()</code> whenever you're done. </p><h2> Web programming with Twisted Web <a name="auto3"></a></h2><p> Web programmers seeking a higher level abstraction than the Resource system should look at <a href="http://www.divmod.org/Home/Projects/Nevow/">Nevow</a>, available as part of the <a href="http://www.divmod.org/Quotient/">Quotient</a> project. Nevow is not distributed as part of Twisted. </p><p> Nevow is based on the same ideas as the earlier <a href="woven.html">Woven</a> framework. Woven only remains part of Twisted in order to support existing projects, and should not be used for new projects. Nevow is a simpler framework which retains the strengths of Woven. </p></div><p><a href="../howto/index.html">Index</a></p><span class="version">Version: 1.3.0</span></body></html>