LinkChecker
                     =============

LinkChecker checks HTML documents for broken links.

It features
o recursive checking
o multithreading
o output in colored or normal text, HTML, SQL, CSV or a sitemap
  graph in GML or XML.
o HTTP/1.1, HTTPS, FTP, mailto:, news:, nntp:, Gopher, Telnet and local
  file links support
o restriction of link checking with regular expression filters for URLs
o proxy support
o username/password authorization for HTTP and FTP
o robots.txt exclusion protocol support
o i18n support
o a command line interface
o a (Fast)CGI web interface (requires HTTP server)


Installing, Requirements, Running
---------------------------------
Read the file INSTALL.


License and Credits
-------------------
LinkChecker is licensed under the GNU Public License.
Credits go to Guido van Rossum for making Python. His hovercraft is
full of eels!
As this program is directly derived from my Java link checker, additional
credits go to Robert Forsman (the author of JCheckLinks) and his
robots.txt parse algorithm.
Nicolas Chauvat <Nicolas.Chauvat@logilab.fr> supplied a patch for
an XML output logger.
I want to thank everybody who gave me feedback, bug reports and
suggestions.


Versioning
----------
Version numbers have the same meaning as Linux Kernel version numbers.
The first number is the major package version. The second number is
the minor package version. An odd second number stands for development
versions, an even number for stable version. The third number is a
package release sequence number.
So for example 1.1.5 is the fifth release of the 1.1 development package.


Included packages
-----------------
DNS from http://pydns.sourceforge.net/
fcgi.py and sz_fcgi.py from http://saarland.sz-sb.de/~ajung/sz_fcgi/
fintl.py from http://sourceforge.net/snippet/detail.php?type=snippet&id=100059

Note that all included packages are modified by me.


Internationalization
--------------------
For german output execute "export LC_MESSAGES=de" in bash or
"setenv LC_MESSAGES de" in tcsh.
Under Windows, execute "set LC_MESSAGES=de".
For french output use 'fr' instead of 'de'.


Code design
-----------
Only if you want to hack on the code.

(1) Look at the linkchecker script. This thing just reads all the
commandline options and stores them in a Config object.

(2) Which leads us directly to the Config class. This class stores all
options and works a little magic: it tries to find out if your platform
supports threads. If so, threading is enabled. If not, it is disabled.
Several functions are replaced with their threaded equivalents if 
threading is enabled.
Another thing are config files. A Config object reads config file options
on initialization so they get handled before any commandline options.

(3) The linkchecker script finally calls linkcheck.checkUrls(), which
calls linkcheck.Config.checkUrl(), which calls linkcheck.UrlData.check().
An UrlData object represents a single URL with all attached data like
validity, check time and so on. These values are filled by the 
UrlData.check() function.
Derived from the base class UrlData are the different URL types: 
HttpUrlData for http:// links, MailtoUrlData for mailto: links, etc.

UrlData defines the functions which are common for *all* URLs, and
the subclasses define functions needed for their URL type.

(4) Lets look at the output. Every output is defined in a Logger class.
Each logger has functions init(), newUrl() and endOfOutput().
We call init() once to initialize the Logger. UrlData.check() calls
newUrl() (through UrlData.logMe()) for each new URL and after all 
checking is done we call endOfOutput(). Easy.
New loggers are created with the Config.newLogger function.