Session4: Persistent Session Management for Quixote 4+

Authors, copyright, and license

Session4 is copyrighted and made available under open source licensing terms for which see LICENSE.txt for the details. The ACKS.txt file lists the orignial authors (of Session2) and anyone who has assisted in the development. RELEASE_NOTES.md summarizes the changes in the current release.

The current author is Robert Ladyman, it@file-away.co.uk

Version

4.0a1 released August 2026 (in development). Version numbers tend to track Quixote

Status

Only the file-storage mechanism DirectorySessionStore is currently working with Quixote 4+

Source code

The source code is managed using Git. You can check out a copy using the command:

git clone https://github.com/rojalator/session4.git

Introduction

Quixote is 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 (by design) forgets the sessions when the Publisher quits. Session4 provides replacement session manager, session and store classes to allow persistence for sessions using Quixote.¹

Session4 version 4.0a1 provides a fully functional² persistent storage back-end for use with Quixote 4 and above (also see Road-map below, for future session4 version notes):-

DirectorySessionStore

Store each pickled session in a file in the designated directory. The filename for a session is the session ID. Uses fcntl file locking. :

    DirectorySessionStore(directory)

This package includes an extended version of Quixote's BaseSessionManager that adds the missing __getitem__() and has_session() functions. Basing this upon BaseSessionManager should allow Session4 to track changes in Quixote much more efficiently (Session 3 had drifted considerably). There is also a Session4 class based upon Quixote's Session that automatically detects changes to attributes (which will be saved) and returns the status (changed or not) via is_dirty().

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.

Road-map

• Session 4 will add support for Postgres, MySQL, Shelve and other back-ends as required.
• Ability to use Session 4 without Quixote (either as Session4 itself or, for example, via Session4NoQuixote)

Getting Session4

Installation

See the installation instructions. You can use "uv" to install:

uv sync

Session4 can be installed via pip (pip3 install session4). Alternatively (or if you also want the documentation) download and unpack the tar.gz file and install the normal Python way.

Documentation

API documentation is available --- either read it on-line or run:

make documentation

This will create files within directories with the docs/ directory. You will need pydoctor installed.

Using session4

As usual for Quixote, you need a store, a manager and then you need to tell Quixote's publisher to use them both but in addition you'll need to tell the session store where to store sessions (at least for a DirectorySessionStore). For example, assuming the directory path is in some_location/, then in your create_publisher() function, you might place the following code:

from session4.DirectorySessionStore import DirectorySessionStore
from session4.Session4Session import Session4, Session4SessionManager

# locate or create the session store.
store = DirectorySessionStore(sessions_directory=some_location, create=True)

# create the session manager.
session_manager = Session4SessionManager(session_store=store, session_class=Session4)

# create the publisher.
publisher = Publisher(..., session_manager=session_manager)

Each session store has different initialization requirements: see the API documentation for more information.

Features

All session4 stores have the following convenience methods:--

setup() : initializes the store. For DirectorySessionStores this does nothing: it is suggested that a directory be created prior to initialisation, so that, for example, a temporary directory can be created or a location can be loaded from Quixote's config file.

.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.

.is_multiprocess_safe and .is_thread_safe : All stores have .is_multiprocess_safe and .is_thread_safe attributes. An application can check these flags and abort if configured inappropriately. The flags are defined as follows:-

• DirectorySessionStore is multiprocess safe because it uses fcntl file 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.

Testing

Session4 comes with both an automatic test suite (via pytest) and an interactive Quxiote test application. To run tests, consult the README.md file in the tests/ directory.

fcntl Caution

On Mac OS X when using PTL, import fcntl before enabling 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.

Changes from Session3

See CHANGES.txt in the docs/ directory

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Footnotes

1. Session3 is based upon the previous Session2 code (designed for, unsurprisingly, Quixote 2) ↩

2. Note that only DirectorySessionStore is working for version 4.0.0 ↩