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<meta name="author" content="John J. Lee <jjl@pobox.com>">
<meta name="date" content="2006-01-05">
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<title>Python web-client programming general FAQs</title>
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<h1>Python web-client programming general FAQs</h1>
<div id="Content">
<ul>
<li>Is there any example code?
<p>There's (still!) a bit of a shortage of example code for ClientCookie
and ClientForm &co., because the stuff I've written tends to either
require access to restricted-access sites, or is proprietary code (and the
same goes for other people's code).
<li>HTTPS on Windows?
<p>Use this <a href="http://pypgsql.sourceforge.net/misc/python22-win32-ssl.zip">
_socket.pyd</a>, or use Python 2.3.
<li>I want to see what my web browser is doing, but standard network sniffers
like <a href="http://www.ethereal.com/">ethereal</a> or netcat (nc) don't
work for HTTPS. How do I sniff HTTPS traffic?
<p>Three good options:
<ul>
<li>Mozilla plugin: <a href="http://livehttpheaders.mozdev.org/">
livehttpheaders</a>.
<li><a href="http://www.blunck.info/iehttpheaders.html">ieHTTPHeaders</a>
does the same for MSIE.
<li>Use <a href="http://lynx.browser.org/">lynx</a> <code>-trace</code>,
and filter out the junk with a script.
</ul>
<p>I'm told you can also use a proxy like <a
href="http://www.proxomitron.info/">proxomitron</a> (never tried it
myself). There's also a commercial <a href="http://www.simtec.ltd.uk/">MSIE
plugin</a>.
<li>Embedded script is messing up my web-scraping. What do I do?
<p>It is possible to embed script in HTML pages (sandwiched between
<code><SCRIPT>here</SCRIPT></code> tags, and in
<code>javascript:</code> URLs) - JavaScript / ECMAScript, VBScript, or
even Python. These scripts can do all sorts of things, including causing
cookies to be set in a browser, submitting or filling in parts of forms in
response to user actions, changing link colours as the mouse moves over a
link, etc.
<p>If you come across this in a page you want to automate, you
have four options. Here they are, roughly in order of simplicity.
<ul>
<li>Simply figure out what the embedded script is doing and emulate it
in your Python code: for example, by manually adding cookies to your
<code>CookieJar</code> instance, calling methods on
<code>HTMLForm</code>s, calling <code>urlopen</code>, etc.
<li>Dump ClientCookie and ClientForm and automate a browser instead.
For example use MS Internet Explorer via its COM automation interfaces, using
the <a href="http://starship.python.net/crew/mhammond/">Python for
Windows extensions</a>, aka pywin32, aka win32all (eg.
<a href="http://vsbabu.org/mt/archives/2003/06/13/ie_automation.html">simple
function</a>, <a href="http://pamie.sourceforge.net/">pamie</a>;
<a href="http://www.oreilly.com/catalog/pythonwin32/chapter/ch12.html">
pywin32 chapter from the O'Reilly book</a>) or
<a href="http://starship.python.net/crew/theller/ctypes/">ctypes</a>
(<a href="http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/305273">
example</a>: may be out of date, since <code>ctypes</code>' COM support is
still evolving).
<a href="http://www.brunningonline.net/simon/blog/archives/winGuiAuto.py.html">This</a>
kind of thing may also come in useful on Windows for cases where the
automation API is lacking.
<a href="http://ftp.acc.umu.se/pub/GNOME/sources/pyphany/">pyphany</a>
is a binding to the <a href="http://www.gnome.org/projects/epiphany/">
epiphany web browser</a>, allowing both plugins and automation code to be
written in Python.
XXX Mozilla automation & XPCOM / PyXPCOM, Konqueror & DCOP / KParts / PyKDE).
<li>Use Java's <a href="httpunit.sourceforge.net">httpunit</a> from
Jython, since it knows some JavaScript.
<li>Get ambitious and automatically delegate the work to an appropriate
interpreter (Mozilla's JavaScript interpreter, for instance). This
approach is the one taken by <a href="../DOMForm">DOMForm</a> (the
JavaScript support is "very alpha", though!).
</ul>
<li>Misc links
<ul>
<li><a href="http://www.crummy.com/software/BeautifulSoup/">Beautiful
Soup</a> is a widely recommended HTML-parsing module.
<li><a href="http://linux.duke.edu/projects/urlgrabber/">urlgrabber</a>
contains useful stuff like persistent connections, mirroring and
throttling, and it looks like most or all of it is well-integrated with
<code>urllib2</code> (originally part of the yum package manager, but
now becoming a separate project).
<li>Another Java thing: <a href="http://maxq.tigris.org/">maxq</a>,
which provides a proxy to aid automatic generation of functional tests
written in Jython using the standard library unittest module (PyUnit)
and the "Jakarta Commons" HttpClient library.
<li>A useful set Zope-oriented links on <a
href="http://viii.dclxvi.org/bookmarks/tech/zope/test">tools for testing
web applications</a>.
<li>O'Reilly book: <a href="">Spidering Hacks</a>. Very Perl-oriented.
<li>Useful
<a href="http://chrispederick.com/work/webdeveloper/"> Firefox extension
</a> which, amongst other things, can display HTML form information and
HTML table structure(thanks to Erno Kuusela for this link).
<li>
<a href="http://www.openqa.org/selenium/">Selenium</a>: In-browser web
functional testing.
<li><a href="http://www.opensourcetesting.org/functional.php">Open
source functional testing tools</a>. A nice list.
<li><a href="http://www.rexx.com/~dkuhlman/quixote_htmlscraping.html">
A HOWTO on web scraping</a> from Dave Kuhlman.
</ul>
<li>Will any of this code make its way into the Python standard library?
<p>The request / response processing extensions to <code>urllib2</code> from
ClientCookie have been merged into <code>urllib2</code> for Python 2.4.
The cookie processing has been added, as module <code>cookielib</code>.
Eventually, I'll submit patches to get the http-equiv, refresh, and
robots.txt code in there too, and maybe <code>mechanize.UserAgent</code>
too (but <em>not</em> <code>mechanize.Browser</code>). The rest, probably
not.
</ul>
<p>I prefer questions and comments to be sent to the <a
href="http://lists.sourceforge.net/lists/listinfo/wwwsearch-general">
mailing list</a> rather than direct to me.
<p><a href="mailto:jjl@pobox.com">John J. Lee</a>,
January 2006.
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