Thanks for the code snippets and advice. But I'm afraid my issue with this is more than just my pickling problem with my LDAP connection objects. It's also the problem I have with Webware having 3 types of session storage that all write to disk at some point. By forcing MemorySessionStores to write to disk (even if it is just on shutdown), Webware has effectively blocked out any way to allow developers to "not" keep session's persistent between app server restarts. I guess I just don't see the need for 3 session storage patterns that effectively all do the same thing at some point or another. Why not just have DynamicSessionStore's and be done with it? There's also a serious security issue with storing a session that may have sensitive information in it onto a pickled file that may reside on a server for a long time. What if I need to store a password or credit card number in a session and it's gets written to disk - that's a BAD thing. I realize that you can code carefully around this but I'm convinced we should have to as Webware developers?
My workaround to suit my needs was to comment out the code in the storeAllSessions(self) method in MemorySessionStore.py. Now things work exactly as I think they should (which by the way mimics the default functionality of Tomcat, Jetty, JBoss and all the other open source Java Servlet containers). So now I have "choice" in how I store my sessions - I can write to disk or not write to disk just by setting a flag in my Application.config file.
Anyway, that's my case.. sorry for being so long-winded. :-)
Thanks again
Mike
On Monday, December 2, 2002, at 11:17 PM, Ian Bicking wrote:
On Mon, 2002-12-02 at 12:07, Michael Engelhart wrote:Hi all -
I wrote about this a month or two ago and didn't really get a response
but it's starting to bite me again.
I'm trying to store LDAP connection objects in the user session and
because the underlying LDAP objects (from the python-ldap.sf.net
modules) aren't "pickleable", on shutdown of the AppServer, an error is
thrown and on top of that the AppServer I guess writes the Session to
disk anyway (which it probably shouldn't) and then when I try and
restart the AppServer, it exits with the following error:
File "./WebKit/SessionMemoryStore.py", line 23, in __init__
File "./WebKit/SessionFileStore.py", line 55, in __getitem__
KeyError: 20021202101928-72a11220b9961fe879564b63447a8d6a
Yes, all types of session stores are persistent -- the only configuration is when they store stuff to disk (immediately, lazily, or on AppServer shutdown). This configuration is really for performance tweaking, it does not introduce any real change in the behavior of the session. I think this is good.I think Webware encourages a more robust application through thisMy problem that I don't get is why when I tell the AppServer to use a MemoryStore model, it still writes to disk. I don't want my sessions to persist after their timeout. There are a million reasons not to want this persistence one of which is that if your objects aren't pickleable, it crashes. I think this should be addressed in the next release as I find it hard to understand the reason behind wanting to store ALL sessions to disk on shutdown or timeout.
behavior, but I can also appreciate that this seems somewhat
paternalistic -- it's your app, after all.
But I really don't think it should be so hard. You could use some sort
of pool, paramaterized on the username/password.
If your LDAP access is threadsafe, you could use:
http://colorstudy.com/software/python/ParamFactory.py
Like:
## AppLDAP.py:
from ParamFactory import ParamFactory
def createLDAPConnection(username, password):
# yada yada
LDAPConnection = ParamFactory(createLDAPConnection)
## SitePage.py:
import AppLDAP
class SitePage(Page):
# yada yada
def ldapConnection(self):
ses = self.session()
return AppLDAP.LDAPConnection(ses.value('username'), ses.value('password'))
## end SitePage
If your LDAP connections aren't threadsafe, you'd need some sort of pool
that was paramaterized, something like DBPool except slightly more
general. Off the top of my head (hence untested):
class Pool:
"""
``creator`` must be callable, and require only positional (not
keyword) arguments. The arguments must be hashable, i.e.,
non-mutable (e.g., strings, numbers, tuples)
"""
def __init__(self, creator, threadsafe=0):
self._creator = creator
self._pool = {}
if threadsafe:
self.__call__ = self._threadsafe__call__
else:
self.__call__ = self._unthreadsafe__call__
self.returnConnection = self._unthreadsafe_returnConnection
self._lock = threading.Lock()
def _threadsafe__call__(self, *args):
try:
return self._pool[args]
except KeyError:
self._pool[args] = self._creator(*args)
return self._pool[args]
def _unthreadsafe__call__(self, *args):
self._lock.acquire()
try:
if not self._pool.has_key(args):
self._pool[args] = []
if not self._pool[args]:
self._pool[args].append(PooledObject(self._unthreadsafe_returnObject,
args, self._creator(*args))
return self._pool[args].pop()
finally:
self._lock.release()
def _unthreadsafe_returnObject(self, args, obj):
self._pool[args].append(obj)
class PooledObject:
def __init__(self, callback, args, obj):
self._callback, self._args = callback, args
self._obj = obj
def close(self):
if self._pool and self._obj is not None:
self._callback(args, self._obj)
self._obj = None
def __del__(self):
self.close()
## End
There are a multitude of improvements that could be made, but this
should be enough for most pooling needs. You can use it in your
SitePage similarly to ParamFactory.
--
Ian Bicking Colorstudy Web Development
[EMAIL PROTECTED] http://www.colorstudy.com
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