httpd::session(n) 1.0 "Tcl Web Server"
httpd::session - Session management
package require httpd::session ?1.0?
The package httpd::session implements session management
for a tcl based web server.
The basic idea is to implement a session as a safe slave interpreter
that holds its state. Each session has a four-character ID, allowing
around 128^4 different sessions, assuming the ASCII character set.
Note: This package does not care where a session id comes
from. They can be provided through hidden form data, or through
cookies, for example. This is in the area of responsibility of the
code making use of the package.
- Session_Create type ?isSafe?
Creates a new session and returns its ID. By default the
interpreter created for the session is marked as save, but this
can be deactivated by specifying false for isSafe.
The type determines what commands are available in the slave
interpreter for the session: All commands in the master interpreter
whose name begins with type_ are made available as
aliases to the new slave. Inside of the slave the prefix
type_ will be stripped off. Additional automatisms: If
the first argument of the command is interp or session
the alias command will automatically called with either the session
interp or the session id. Note that the latter allows determination of
Standard commands available to the seesion interpreter are:
Returns the seesion id.
Returns an increasing sequence number which can be used to chain
together pages and detect bookmarks and "backs" that screw things up.
Set or get the current session "group". In the session interp a group
is simply an array.
Get a value from the current "group", or a default value.
- Session_CreateWithID type id ?isSafe?
Like Session_Create, except that the id is not randomly
chosen, but specified by the caller.
- Session_Destroy id
This command destroys the specified session.
- Session_Reap age ?type?
This command destroys all sessions which have not been touched for at
least age seconds and are matching the type. The latter is
a regexp pattern and defaults to .*, i.e. everything matches.
- Session_Match querylist ?type? ?error_name? ?isSafe?
Finds a session based on the form data which is stored in the
dictionary query. Assumes the existence of a form variable named
If the value of that variable is new a new session is
created. If it is kill ID the session with that id is
destroyed. Else the value is used to look for an existing session. If
a type is specified the found session has to be of that type or
an error will be thrown. If the session has a sequence number the
system expects a form variable sequence and its value has
error_name is the name of the variable where an error message
will be stored if something goes wrong. The last argument,
isSafe has the same meaning as for Sequence_Create.
The command returns the session id for the session, or the empty
string if none could be found.
- Session_Authorized id
This command returns the interpreter for the session having the
specified id and installs privileged aliases. If the session
does not exist it will be created.
An authorized interpreter has two additional commands available
- require tag
Loads and initializes packages based on the tag. Calls
a command "tag_Init" with the session array and returns
its result as the HTML generated by this command.
Destroys the session.
- Session_Require id tag
See above, Session_Authorized. This implements the require
command to load and initialize special packages in the session
- Session_Import valid array ?interp?
Imports the valid components of the array in interp as
variables into the local scope. valid is the name of an array
whose keys are the valid components to import (prefix with a dash). If
valid is the empty string all components of the array are imported.
If no interp was specified the main interp is used as source.
- Session_Session arg
Returns the argument. This implements the session command
for session interpreters.
- Session_Sequence id
Generates a sequence value and returns it. This implements the
sequence command for session interpreters.
- Session_Variable id var ?value?
Sets or gets data from the global state associated with the session
interpreter. This is used to implement the group command for
- Session_Value id var ?default?
Gets a value from the current group, or a default if the group does
not have a component called var. This implements the value
command for session interpreters.
sessions, web server
Copyright © 2003 Andreas Kupries <firstname.lastname@example.org>