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mezzio-session

Web applications often need to persist user state between requests, and the generally accepted way to do so is via sessions. While PHP provides its own session extension, it:

  • uses global functions that affect global state.
  • relies on a superglobal for access to both read and write the session data.
  • incurs either filesystem or network I/O on every request, depending on the session storage handler.
  • can clobber the Set-Cookie header when other processes also set it.

Some projects, such as psr-7-sessions/storageless, take a different approach, using JSON Web Tokens (JWT).

The goals of mezzio-session are:

  • to abstract the way users interact with session storage.
  • to abstract how sessions are persisted, to allow both standard ext-session, but also other paradigms such as JWT.
  • to provide session capabilities that "play nice" with PSR-7 and middleware.

Installation

Use Composer to install this package:

$ composer require mezzio/mezzio-session

However, the package is not immediately useful unless you have a persistence adapter. If you are okay with using ext-session, you can install the following package as well:

$ composer require mezzio/mezzio-session-ext

Features

mezzio-session provides the following:

  • Interfaces for:
    • session containers
    • session persistence
  • An implementation of the session container.
  • A "lazy-loading" implementation of the session container, to allow delaying any de/serialization and/or I/O processes until session data is requested; this implementation decorates a normal session container.
  • PSR-7 middleware that:
    • composes a session persistence implementation.
    • initializes the lazy-loading session container, using the session persistence implementation.
    • delegates to the next middleware, passing the session container into the request.
    • finalizes the session before returning the response.

Persistence implementations locate session information from the requests (e.g., via a cookie) in order to initialize the session. On completion of the request, they examine the session container for changes and/or to see if it is empty, and provide data to the response so as to notify the client of the session (e.g., via a Set-Cookie header).

Note that the goals of this package are solely focused on session persistence and access to session data by middleware. If you also need other features often related to session data, you may want to consider the following packages:

  • mezzio-flash: provides flash message capabilities.
  • mezzio-csrf: provides CSRF token generation, storage, and verification, using either a session container, or flash messages.

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