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# This extension demonstrates some advanced features of the Python ISAPI
# framework.
# We demonstrate:
# * Reloading your Python module without shutting down IIS (eg, when your
# .py implementation file changes.)
# * Custom command-line handling - both additional options and commands.
# * Using a query string - any part of the URL after a '?' is assumed to
# be "variable names" separated by '&' - we will print the values of
# these server variables.
# * If the tail portion of the URL is "ReportUnhealthy", IIS will be
# notified we are unhealthy via a HSE_REQ_REPORT_UNHEALTHY request.
# Whether this is acted upon depends on if the IIS health-checking
# tools are installed, but you should always see the reason written
# to the Windows event log - see the IIS documentation for more.
import os
import stat
import sys
from isapi import isapicon
from isapi.simple import SimpleExtension
if hasattr(sys, "isapidllhandle"):
import win32traceutil
# Notes on reloading
# If your HttpFilterProc or HttpExtensionProc functions raises
# 'isapi.InternalReloadException', the framework will not treat it
# as an error but instead will terminate your extension, reload your
# extension module, re-initialize the instance, and re-issue the request.
# The Initialize functions are called with None as their param. The
# return code from the terminate function is ignored.
#
# This is all the framework does to help you. It is up to your code
# when you raise this exception. This sample uses a Win32 "find
# notification". Whenever windows tells us one of the files in the
# directory has changed, we check if the time of our source-file has
# changed, and set a flag. Next imcoming request, we check the flag and
# raise the special exception if set.
#
# The end result is that the module is automatically reloaded whenever
# the source-file changes - you need take no further action to see your
# changes reflected in the running server.
# The framework only reloads your module - if you have libraries you
# depend on and also want reloaded, you must arrange for this yourself.
# One way of doing this would be to special case the import of these
# modules. Eg:
# --
# try:
# my_module = reload(my_module) # module already imported - reload it
# except NameError:
# import my_module # first time around - import it.
# --
# When your module is imported for the first time, the NameError will
# be raised, and the module imported. When the ISAPI framework reloads
# your module, the existing module will avoid the NameError, and allow
# you to reload that module.
import threading
import win32con
import win32event
import win32file
import winerror
from isapi import InternalReloadException
try:
reload_counter += 1
except NameError:
reload_counter = 0
# A watcher thread that checks for __file__ changing.
# When it detects it, it simply sets "change_detected" to true.
class ReloadWatcherThread(threading.Thread):
def __init__(self):
self.change_detected = False
self.filename = __file__
if self.filename.endswith("c") or self.filename.endswith("o"):
self.filename = self.filename[:-1]
self.handle = win32file.FindFirstChangeNotification(
os.path.dirname(self.filename),
False, # watch tree?
win32con.FILE_NOTIFY_CHANGE_LAST_WRITE,
)
threading.Thread.__init__(self)
def run(self):
last_time = os.stat(self.filename)[stat.ST_MTIME]
while 1:
try:
rc = win32event.WaitForSingleObject(self.handle, win32event.INFINITE)
win32file.FindNextChangeNotification(self.handle)
except win32event.error as details:
# handle closed - thread should terminate.
if details.winerror != winerror.ERROR_INVALID_HANDLE:
raise
break
this_time = os.stat(self.filename)[stat.ST_MTIME]
if this_time != last_time:
print("Detected file change - flagging for reload.")
self.change_detected = True
last_time = this_time
def stop(self):
win32file.FindCloseChangeNotification(self.handle)
# The ISAPI extension - handles requests in our virtual dir, and sends the
# response to the client.
class Extension(SimpleExtension):
"Python advanced sample Extension"
def __init__(self):
self.reload_watcher = ReloadWatcherThread()
self.reload_watcher.start()
def HttpExtensionProc(self, ecb):
# NOTE: If you use a ThreadPoolExtension, you must still perform
# this check in HttpExtensionProc - raising the exception from
# The "Dispatch" method will just cause the exception to be
# rendered to the browser.
if self.reload_watcher.change_detected:
print("Doing reload")
raise InternalReloadException
url = ecb.GetServerVariable("UNICODE_URL")
if url.endswith("ReportUnhealthy"):
ecb.ReportUnhealthy("I'm a little sick")
ecb.SendResponseHeaders("200 OK", "Content-Type: text/html\r\n\r\n", 0)
print("<HTML><BODY>", file=ecb)
qs = ecb.GetServerVariable("QUERY_STRING")
if qs:
queries = qs.split("&")
print("<PRE>", file=ecb)
for q in queries:
val = ecb.GetServerVariable(q, "<no such variable>")
print("%s=%r" % (q, val), file=ecb)
print("</PRE><P/>", file=ecb)
print("This module has been imported", file=ecb)
print("%d times" % (reload_counter,), file=ecb)
print("</BODY></HTML>", file=ecb)
ecb.close()
return isapicon.HSE_STATUS_SUCCESS
def TerminateExtension(self, status):
self.reload_watcher.stop()
# The entry points for the ISAPI extension.
def __ExtensionFactory__():
return Extension()
# Our special command line customization.
# Pre-install hook for our virtual directory.
def PreInstallDirectory(params, options):
# If the user used our special '--description' option,
# then we override our default.
if options.description:
params.Description = options.description
# Post install hook for our entire script
def PostInstall(params, options):
print()
print("The sample has been installed.")
print("Point your browser to /AdvancedPythonSample")
print("If you modify the source file and reload the page,")
print("you should see the reload counter increment")
# Handler for our custom 'status' argument.
def status_handler(options, log, arg):
"Query the status of something"
print("Everything seems to be fine!")
custom_arg_handlers = {"status": status_handler}
if __name__ == "__main__":
# If run from the command-line, install ourselves.
from isapi.install import *
params = ISAPIParameters(PostInstall=PostInstall)
# Setup the virtual directories - this is a list of directories our
# extension uses - in this case only 1.
# Each extension has a "script map" - this is the mapping of ISAPI
# extensions.
sm = [ScriptMapParams(Extension="*", Flags=0)]
vd = VirtualDirParameters(
Name="AdvancedPythonSample",
Description=Extension.__doc__,
ScriptMaps=sm,
ScriptMapUpdate="replace",
# specify the pre-install hook.
PreInstall=PreInstallDirectory,
)
params.VirtualDirs = [vd]
# Setup our custom option parser.
from optparse import OptionParser
parser = OptionParser("") # blank usage, so isapi sets it.
parser.add_option(
"",
"--description",
action="store",
help="custom description to use for the virtual directory",
)
HandleCommandLine(
params, opt_parser=parser, custom_arg_handlers=custom_arg_handlers
)