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|library(http/http_session): HTTP Session management|
This library defines session management based on HTTP cookies.
Session management is enabled simply by loading this module. Details can
be modified using http_set_session_options/1.
By default, this module creates a session whenever a request is
processes that is inside the hierarchy defined for session handling (see
path option in
Automatic creation of a session can be stopped using the option
be used to create a session if
noauto is enabled. Sessions
can be closed using http_close_session/1.
If a session is active, http_in_session/1 returns the current session and http_session_assert/1 and friends maintain data about the session. If the session is reclaimed, all associated data is reclaimed too.
Begin and end of sessions can be monitored using
The broadcasted messages are:
For example, the following calls
whenever a session terminates. Please note that sessions ends are not
scheduled to happen at the actual timeout moment of the session.
Instead, creating a new session scans the active list for timed-out
sessions. This may change in future versions of this library.
:- listen(http_session(end(SessionId, Peer)), end_session(SessionId)).
0(zero) disables timeout.
/. Cookies are only sent if the HTTP request path is a refinement of Path.
auto(default), which creates a session if there is a request whose path matches the defined session path or
noauto, in which cases sessions are only created by calling http_open_session/2 explicitely.
active, which starts a thread that performs session cleanup at close to the moment of the timeout or
passive, which runs session GC when a new session is created.
strict- The SameSite attribute prevents the CSRF vulnerability. strict has best security, but prevents links from external sites from operating properly. lax stops most CSRF attacks against REST endpoints but rarely interferes with legitimage operations.
noneremoves the samesite attribute entirely. Caution: The value
noneexposes the entire site to CSRF attacks.
In addition, extension libraries can define session_option/2
to make this predicate support more options. In particular,
library(http/http_redis_plugin) defines the following
permission_error(set, http_session, Setting)if setting a setting that is not supported on per-session basis.
|SessionId||is an atom.|
session(ID)from the current HTTP request (see http_current_request/1). The value is cached in a backtrackable global variable
http_session_id. Using a backtrackable global variable is safe because continuous worker threads use a failure driven loop and spawned threads start without any global variables. This variable can be set from the commandline to fake running a goal from the commandline in the context of a session.
false) and the current request is part of a session, generate a new session-id. By default, this predicate returns the current session as obtained with http_in_session/1.
permission_error(open, http_session, CGI)if this call is used after closing the CGI header.
The broadcast is done before the session data is destroyed and the listen-handlers are executed in context of the session that is being closed. Here is an example that destroys a Prolog thread that is associated to a thread:
:- listen(http_session(end(SessionId, _Peer)), kill_session_thread(SessionID)). kill_session_thread(SessionID) :- http_session_data(thread(ThreadID)), thread_signal(ThreadID, throw(session_closed)).
Succeed without any effect if SessionID does not refer to an active session.
is called from a handler operating in the current session and the CGI
stream is still in state
header, this predicate emits a
expire the cookie.
library(http/http_redis_plugin), storing all session data in a redis database.