Package wsgiref :: Module handlers :: Class BaseHandler

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Class BaseHandler

Known Subclasses:

SimpleHandler

Manage the invocation of a WSGI application

Nested Classes

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wsgi_file_wrapper
Wrapper to convert file-like objects to iterables

headers_class
Manage a collection of HTTP response headers

Instance Methods

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run(self, application)
Invoke the application

setup_environ(self)
Set up the environment for one request

finish_response(self)
Send any iterable data, then close self and the iterable

get_scheme(self)
Return the URL scheme being used

set_content_length(self)
Compute Content-Length or switch to chunked encoding if possible

cleanup_headers(self)
Make any necessary header changes or defaults

start_response(self, status, headers, exc_info=None)
'start_response()' callable as specified by PEP 333

send_preamble(self)
Transmit version/status/date/server, via self._write()

write(self, data)
'write()' callable as specified by PEP 333

sendfile(self)
Platform-specific file transmission

finish_content(self)
Ensure headers and content have both been sent

close(self)
Close the iterable (if needed) and reset all instance vars

send_headers(self)
Transmit headers to the client, via self._write()

result_is_file(self)
True if 'self.result' is an instance of 'self.wsgi_file_wrapper'

client_is_modern(self)
True if client can accept status and headers

log_exception(self, exc_info)
Log the 'exc_info' tuple in the server log

handle_error(self)
Log current error, and send error output to client if possible

error_output(self, environ, start_response)
WSGI mini-app to create error output

_write(self, data)
Override in subclass to buffer data for send to client

_flush(self)
Override in subclass to force sending of recent '_write()' calls

get_stdin(self)
Override in subclass to return suitable 'wsgi.input'

get_stderr(self)
Override in subclass to return suitable 'wsgi.errors'

add_cgi_vars(self)
Override in subclass to insert CGI variables in 'self.environ'

Class Variables

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wsgi_version = (1, 0)

wsgi_multithread = True

wsgi_multiprocess = True

wsgi_run_once = False

origin_server = True

http_version = '1.0'

server_software = None

os_environ = {'BASH_ENV': '/home/edloper/.bashrc', 'CONSOLE': ...

traceback_limit = None

error_status = '500 Dude, this is whack!'

error_headers = [('Content-Type', 'text/plain')]

error_body = 'A server error occurred. Please contact the adm...

result = None

status = None

headers_sent = False

headers = None

bytes_sent = 0

Method Details

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finish_response(self)

Send any iterable data, then close self and the iterable

Subclasses intended for use in asynchronous servers will want to redefine this method, such that it sets up callbacks in the event loop to iterate over the data, and to call 'self.close()' once the response is finished.

cleanup_headers(self)

Make any necessary header changes or defaults

Subclasses can extend this to add other defaults.

sendfile(self)

Platform-specific file transmission

Override this method in subclasses to support platform-specific file transmission. It is only called if the application's return iterable ('self.result') is an instance of 'self.wsgi_file_wrapper'.

This method should return a true value if it was able to actually transmit the wrapped file-like object using a platform-specific approach. It should return a false value if normal iteration should be used instead. An exception can be raised to indicate that transmission was attempted, but failed.

NOTE: this method should call 'self.send_headers()' if 'self.headers_sent' is false and it is going to attempt direct transmission of the file.

close(self)

Close the iterable (if needed) and reset all instance vars

Subclasses may want to also drop the client connection.

log_exception(self, exc_info)

Log the 'exc_info' tuple in the server log

Subclasses may override to retarget the output or change its format.

error_output(self, environ, start_response)

WSGI mini-app to create error output

By default, this just uses the 'error_status', 'error_headers', and 'error_body' attributes to generate an output page. It can be overridden in a subclass to dynamically generate diagnostics, choose an appropriate message for the user's preferred language, etc.

Note, however, that it's not recommended from a security perspective to spit out diagnostics to any old user; ideally, you should have to do something special to enable diagnostic output, which is why we don't include any here!

_write(self, data)

Override in subclass to buffer data for send to client

It's okay if this method actually transmits the data; BaseHandler just separates write and flush operations for greater efficiency when the underlying system actually has such a distinction.

_flush(self)

Override in subclass to force sending of recent '_write()' calls

It's okay if this method is a no-op (i.e., if '_write()' actually sends the data.

Class Variable Details

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os_environ

Value:

{'BASH_ENV': '/home/edloper/.bashrc',
 'CONSOLE': '/dev/console',
 'CVSROOT': '/home/edloper/cvs',
 'DISPLAY': ':1.0',
 'DPKG_ARCH': 'i386',
 'EDITOR': 'emacs',
 'FONT_PATH': '/home/edloper/.afterstep/desktop/fonts/:/usr/share/afte
rstep/desktop/fonts/:/usr/share/fonts/default/TrueType/:/usr/share/fon
...

error_body

Value:

'A server error occurred.  Please contact the administrator.'