Package: session3
Authors:R J Ladyman(based upon session2 by C Titus Brown and Mike Orr)Email:it@file-away.co.ukLicense:MIT  (http://www.opensource.org/licenses/mit-license.php)Version:3.0.0 released 2018-12-02Status:Only the file-storage mechanism (DirectorySessionStore) is working with Quixote 3.0ContentsIntroductionChanges from Session2Road-mapGetting Session3InstallationDocumentationUsing session3FeaturesInteractive TestingfcntlCautionIntroductionQuixoteis a Python Web application framework.  It comes with an
in-memory session manager, which works but is incompatible with
multi-process servers (SCGI, CGI, etc).  It also forgets the sessions
when the Publisher quits.Session3solves these problems by
providing a new session manager class and a simple back-end storage
API. Session3 is based upon the previousSession2code (for, unsurprisingly,
Quixote 2).Session3version 3.0.0 provides a fully functional[1]persistent storageback-end for use with Quixote 3.0.0 (also seeRoad-mapbelow, for later version notes):-DirectorySessionStoreStore each pickled session in a file in the designated directory.  The
filename is the session ID.  Usesfcntlfile locking.DirectorySessionStore(directory)This package includes a refactoredSessionManagerthat makes it easy to develop
additional back ends, and a simplified Session class (no.is_dirtymethod).
It supports the usual.user,.set_user()and.has_info()attributes, and you can also set your own attributes which will be saved.It’s quite likely that the session stores can be adapted for use with other
Web frameworks; let us know if you do this so we can link to you and / or
include helpful code in the package.Changes from Session2SinceSession2was released a number of packages that were referred to in the documentation (and the source)
have either ceased to exist or moved into maintenance mode and Session3 itself is solely for Python 3.Noseis in maintenance modeThe web-site forTwillhas disappeared. Existing Twill code appears to be Python 2 onlyRoad-mapQuixote (at time of writing - January 2019) is at version 3.0.0 and Session3 works with that
(stable) version.Quixote 3.1.x has added BaseSessionManager and SessionStore classes requiring Session3
to be updated (the new
Session3 version-number will reflect the Quixote version it works with).Getting Session3Download the latest version here:http://www.file-away.co.uk/session3/dist/session3-3.0.0.tar.gzInstallationSession3 can be installed via pip (pip3 install session3).
Alternatively (or if you also want the documentation) download and unpack
the tar.gz file, and install the normal Python way (python3 setup.py install). Note that Session3 requires Quixote 3.0.0 — this
is also available in pip.DocumentationAPI documentationis available as isLiterate Programming documentation—
you’ll need to extract it from the tar.gz file.You can read it on-line at:http://www.file-away.co.uk/session3/README.htmlUsing session3You need astore, amanagerand then you need to tell Quixote’s
publisher to use them both: in yourcreate_publisherfunction, place the following code:# create the session store.
from session3.store.DirectorySessionStore import DirectorySessionStore
from session3.SessionManager import SessionManager

# create the session manager.
store = DirectorySessionStore(path.expanduser(some_location), create=True)
session_manager = SessionManager(store)

# create the publisher.
from quixote.publish import Publisher
publisher = Publisher(..., session_manager.session_manager)Each session store has different initialization requirements:[1]see
theAPI documentationor theliterate programming documentationfor more information.FeaturesAll session stores have the following methods, which are called by the session
manager:-.load_session,.save_session,.delete_session,.has_session.They also have these convenience methods:-.setup():initializes the store..delete_old_sessions(minutes):deletes sessions that haven’t been modified for N minutes.
This is meant for your application maintenance program; e.g.,
a daily cron job..iter_sessions():Return an iterable of (id, session) for all sessions
in the store.  This is for admin applications that want to browse the sessions.
The DirectorySession will raise aNotImplementedError[3].All stores have.is_multiprocess_safeand.is_thread_safeattributes.
An application can check these flags and abort if configured inappropriately.
The flags are defined as follows:-DirectorySessionStore is multiprocess safe because it usesfcntlfile
locking.  This limits its use to POSIX.  See the fcntl caution below.  It may
be thread safe because it always locks-unlocks within the same method, but we
don’t know for sure so the attribute is false.[1]Interactive Testingsession3 comes with an interactive web test application. To run the web demo,
cd to thetest/directory in the application source and run:$ test_session2.py directoryPoint your web browser tohttp://localhost:8080/and play around.
You can use--host=hostnameand--port=Nto bind to a different hostname
or port.Press ctrl-C to quit the demo (or command-C on the Mac, or ctrl-Break on
Windows).fcntlCautionOn Mac OS X when using PTL, importfcntlbeforeenabling PTL.
Otherwise the import hook may load the deprecated FCNTL.py instead due to
the Mac’s case-insensitive filesystem, which will cause errors down the road.
This was supposedly fixed in Python 2.4, which doesn’t have FCNTL.py.[1](1,2,3)Note that onlyDirectorySessionStoreis working for version 3.0[2]DictSession is especially useful for applications that may want
to usePaste’s session middleware in the future, because it is dict-based.
However, the migration for.userand.set_user()is not yet clear.[3]For the Session2 code, thiswasimplemented butonlyfor MySQL