pyblosxom wsgi application

"""
WSGI application launcher function for Pyblosxom.


Dependencies:
    - Pyblosxom 1.2+
    - wsgiref library from http://cvs.eby-sarna.com/wsgiref/
    - if run with mod_python: mp_wsgi_handler.py (mod_python wsgi wrapper)
        from http://www.c-area.ch/code/
    - if run with twisted: twisted_wsgi.py (twisted wsgi wrapper)
        from http://svn.colorstudy.com/trunk/WSGIKit/wsgikit/


Configuration:
    - put this file in your weblog folder (where pyblosxom.cgi is)
    - mod_python:
        Note: If you have a folder in your document root that has the same name as the 
          Location used below, the SCRIPT_NAME and PATH_INFO variables will be broken.
          You should keep your blog's files outside your document root.
        <Location /weblog>
            PythonDebug On
            SetHandler python-program
            # set PythonPath to the folders containing the files.
            PythonPath "['/path/to/mp_wsgi_handler', '/path/to/wsgi_app']+sys.path"
            PythonHandler mp_wsgi_handler::wsgi_handler
            # this should be the same as Location
            PythonOption ApplicationPath /weblog
            PythonOption application wsgi_app::application
        </Location>
        

Todo:
    - more documentation
    - example configuration for twisted


Revisions:
    $Log: wsgi_app.py,v $
    Revision 1.8  2005/02/05 19:13:55  sar
    added exception handling

$Id: wsgi_app.py,v 1.8 2005/02/05 19:13:55 sar Exp $
"""
__author__ = "Steven Armstrong <sa at c-area dot ch>"
__version__ = "$Revision: 1.8 $ $Date: 2005/02/05 19:13:55 $"
__url__ = "http://www.c-area.ch/code/"
__description__ = "WSGI application launcher for Pyblosxom"
__license__ = "Pyblosxom"


# Python imports
import sys

# Pyblosxom imports
from Pyblosxom.pyblosxom import PyBlosxom
from Pyblosxom import tools
from config import py as cfg

_debug = False

def _getExcInfo():
    try: from cStringIO import StringIO
    except ImportError: from StringIO import StringIO
    import traceback
    (exc_type, exc_value, tb) = sys.exc_info()
    exc_file = StringIO()
    traceback.print_exception(exc_type, exc_value, tb, file=exc_file)
    exc_string = exc_file.getvalue()
    return exc_string

def application(env, start_response):

    try: # regular application code here

        # ensure that PATH_INFO exists. a few plugins break if this is missing.
        if not 'PATH_INFO' in env:
            env['PATH_INFO'] = ""
    
        p = PyBlosxom(cfg, env)
        p.run()
    
        response = p.getResponse()
    
        if _debug:
            log = tools.getLogger("pyblosxom")            
            log.setLevel(log.DEBUG)
            log.debug("status: %s", response.status)
            log.debug("headers: %s", response.headers)

        write = start_response(response.status, list(response.headers.items()))
        response.seek(0)
    
        # this would be the recommended way
        #return response
    
        # but this seems to be faster
        write(response.read())
        return []

    except:
        # XXX should trap runtime issues like MemoryError, KeyboardInterrupt
        #     in a separate handler before this bare 'except:'...
        
        # log the exception to /<logdir>/error.log
        tools.log_exception()
        status = "500 Oops"
        response_headers = [("content-type","text/plain")]
        start_response(status, response_headers)
        result = ["Pyblosxom WSGI application: A server error occurred.  Please contact the administrator."]
        if _debug:
            result.append("\n")
            result.append(_getExcInfo())
        return result