Storing server-side values for your applications or sessions.
Please read the <<a_manual chapter="server-state" | Eliom manual >> before this page to learn how server side state works.
<<outline| <<header| **Table of contents** >> >>
Managing the state of an application
Closing sessions, removing state data and services
Delete server-side (volatile and persistent) state data and services for a session, a group of sessions, a client process or a request.
Use that function to close a session (using scope Eliom_common.default_session_scope).
Closing a group of sessions will close all sessions in the group.
By default will remove both secure and unsecure data and services, unless ~secure is present.
Warning: you may also want to unset some request-scoped Eliom references when discarding a state.
val discard_all_scopes : ?secure:bool -> unit -> unit Lwt.tRemove current state data.
If the optional parameter ?persistent is not present, will remove both volatile and persistent data. Otherwise only volatile or persistent data.
Remove all services registered for the given scope (the default being `Session).
State status
The following functions return the current state of the state for a given scope:
Alive_state means that data has been recorded for this scopeEmpty_state means that there is no data for this scopeExpired_state means that data for this scope has been removed because the timeout has been reached.
The default scope is `Session.
type state_status = | Alive_state| Empty_state| Expired_state
User cookies
If you want to store a client-side state, and ask the browser to send it back with each request, you can set manually your own cookies. Usual cookies correspond to scope `Session (that is, one browser). The browser send them with each request to the same Web site. But Eliom also implements client-side process cookies (scope `Client_process), that behave in the same way, but for one instance of the client-side Eliom program (if there is one).
Cookies can be limited to a subsite using the ?path optional parameter. This path is relative to the main path of your Web site. (It is not possible to set a cookie for a subsite larger than your current Web site).
Cookies can have an expiration date, specified (in seconds since the 1st of January 1970) in the optional parameter ?exp (see how to set default expiration dates below).
Secure cookies are sent by the browser only with HTTPS (default: false).
val set_cookie :
?cookie_level:Eliom_common.cookie_level ->
?path:string list ->
?exp:float ->
?secure:bool ->
name:string ->
value:string ->
unit ->
unitAsk the browser to record a cookie.
Ask the browser to remove a cookie.
Session groups
If your Web site has users, it is a good idea to group together all the sessions for one user. Otherwise, you may want to group sessions according to another criterion.
Session groups may be used for example to limit the number of sessions one user can open at the same time, or to implement a "close all your sessions" feature. Usually, the group is the user name.
Putting a session in a group, removing a session from a group
sets the group to which belong the service session.
If the optional ?set_max parameter is present, also sets the maximum number of sessions in the group. Default: follow current configuration for the group or default configuration if the group does not exist.
If ~secure is true, it will affect the secure session (secure cookies), otherwise (default), the unsecure one (behavior change in Eliom 4).
Remove the session from its group. Will not close the session if it contains data.
returns the group to which belong the service session. If the session does not belong to any group, or if no session is opened, return None.
returns the number of sessions in the group. If he session does not belong to any group or if no session is opened, returns None
sets the group to which belong the volatile data session.
If the optional ?set_max parameter is present, also sets the maximum number of sessions in the group. Default: follow current configuration for the group or default configuration if the group does not exist.
Remove the session from its group. Will not close the session if it contains data.
returns the group to which belong the data session. If the session does not belong to any group, or if no session is opened, return None.
returns the number of sessions in the group. If he session does not belong to any group or if no session is opened, returns None
val set_persistent_data_session_group :
?set_max:int option ->
?scope:Eliom_common.session_scope ->
?secure:bool ->
string ->
unit Lwt.tsets the group to which belong the persistent session.
If the optional ?set_max parameter is present, also sets the maximum number of sessions in the group. When ~set_max:None is present, the number of session is unlimited. Default: follow current configuration for the group or default configuration if the group does not exist.
Remove the session from its group. Will not close the session if it contains data.
returns the group to which belong the persistent session. If the session does not belong to any group, or if no session is opened, return None.
Maximum group size
The following functions of this section set the maximum number of sessions in a session group, for the different kinds of session. This won't modify existing groups. That value will be used only as default value if you do not specify the optional parameter ?set_max of function Eliom_state.set_volatile_data_session_group.
If there is no group, the number of sessions is limitated by sub network (which can be a problem for example if the server is behind a reverse proxy). It is highly recommended to use session groups!
- Default number of sessions in a group: 5
- Default number of sessions in a sub network: 1000000
- Default IPV4 sub network: /16
- Default IPV6 sub network: /56
These default can be changed from configuration file and/or using these functions.
If ~override_configfile is true (default (false), then the function will set the value even if it has been modified in the configuration file. It means that by default, these functions have no effect if there is a value in the configuration file. This gives the ability to override the values chosen by the module in the configuration file. Use ~override_configfile:true for example if your Eliom module wants to change the values afterwards (for example in the site configuration Web interface).
val set_default_max_service_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of service sessions in a session group (see above).
val set_default_max_volatile_data_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile data sessions in a session group (see above).
val set_default_max_persistent_data_sessions_per_group :
?override_configfile:bool ->
int option ->
unitSets the maximum number of persistent data sessions in a session group (see above). None means "no limitation".
val set_default_max_volatile_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile sessions (data and service) in a session group (see above).
val set_default_max_service_sessions_per_subnet :
?override_configfile:bool ->
int ->
unitSets the maximum number of service sessions in a subnet (see above).
val set_default_max_volatile_data_sessions_per_subnet :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile data sessions in a subnet (see above).
val set_default_max_volatile_sessions_per_subnet :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile sessions (data and service) in a subnet (see above).
val set_default_max_service_tab_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of tab service sessions in a session group (see above).
val set_default_max_volatile_data_tab_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile data tab sessions in a session group (see above).
val set_default_max_persistent_data_tab_sessions_per_group :
?override_configfile:bool ->
int option ->
unitSets the maximum number of persistent data tab sessions in a session group (see above).
val set_default_max_volatile_tab_sessions_per_group :
?override_configfile:bool ->
int ->
unitSets the maximum number of volatile tab sessions (data and service) in a session group (see above).
val set_ipv4_subnet_mask : ?override_configfile:bool -> int -> unitSets the mask for subnet (IPV4).
val set_ipv6_subnet_mask : ?override_configfile:bool -> int -> unitSets the mask for subnet (IPV6).
Sets the maximum number of service sessions in the current session group (or for the client sub network, if there is no group).
val set_max_volatile_data_states_for_group_or_subnet :
scope:Eliom_common.user_scope ->
?secure:bool ->
int ->
unitSets the maximum number of volatile data sessions in the current session group (or for the client sub network, if there is no group).
Sets the maximum number of volatile sessions (both data and service sessions) in the current group (or for the client sub network, if there is no group).
Expiration of cookies and timeouts
Cookie expiration
The functions in this section ask the browser to set the state cookie expiration date, for the different kinds of session, in seconds, since the 1st of January 1970. None means the cookie will expire when the browser is closed. There is no way to set cookies for an infinite time on browsers. By default, Eliom sets default expiration date to 10 years after opening the session.
By default, it will affect regular browser cookies (sessions). But if you set ~cookie_level:`Client_process, it will only affect the client-side Eliom process (if there is one), which simulates some kind of "tab cookies".
Sets the cookie expiration date for the current service state (see above).
Sets the cookie expiration date for the current data state (see above).
val set_persistent_data_cookie_exp_date :
cookie_scope:Eliom_common.cookie_scope ->
?secure:bool ->
float option ->
unit Lwt.tSets the cookie expiration date for the persistent state (see above).
Global configuration of state timeouts
The following functions set the timeout for states, for the different kinds of states. States will be closed after this amount of time of inactivity from the user. None means no timeout.
The optional parameter ?recompute_expdates is false by default. If you set it to true, the expiration dates for all states in the table will be recomputed with the new timeout. That is, the difference between the new timeout and the old one will be added to their expiration dates (asynchronously, by another Lwt thread, as this can take a long time). States whose timeout has been set individually with functions like Eliom_state.set_volatile_data_state_timeout won't be affected.
If ~scope_hierarchy is not present, it is the default for all scope hierarchies, and in that case recompute_expdates is ignored. ~scope_hierarchy:None means the default scope hierarchy.
If ~override_configfile is true (default (false), then the function will set the timeout even if it has been modified in the configuration file. It means that by default, these functions have no effect if there is a value in the configuration file. This gives the ability to override the values chosen by the module in the configuration file. Use ~override_configfile:true for example if your Eliom module wants to change the values afterwards (for example in the site configuration Web interface).
val set_global_volatile_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
?recompute_expdates:bool ->
?override_configfile:bool ->
float option ->
unitSets the (server side) timeout for volatile (= "in memory") sessions (both service session and volatile data session).
val set_global_service_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
?recompute_expdates:bool ->
?override_configfile:bool ->
float option ->
unitSets the (server side) timeout for service states.
val set_default_global_service_state_timeout :
cookie_level:[< Eliom_common.cookie_level ] ->
?override_configfile:bool ->
float option ->
unitval set_global_volatile_data_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
?recompute_expdates:bool ->
?override_configfile:bool ->
float option ->
unitSets the (server side) timeout for volatile (= "in memory") data states.
val set_default_global_volatile_data_state_timeout :
cookie_level:[< Eliom_common.cookie_level ] ->
?override_configfile:bool ->
float option ->
unitval set_global_persistent_data_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
?recompute_expdates:bool ->
?override_configfile:bool ->
float option ->
unitSets the (server side) timeout for persistent states.
val set_default_global_persistent_data_state_timeout :
cookie_level:[< Eliom_common.cookie_level ] ->
?override_configfile:bool ->
float option ->
unitReturns the (server side) timeout for service states.
val get_global_volatile_data_state_timeout :
?secure:bool ->
cookie_scope:[< Eliom_common.cookie_scope ] ->
unit ->
float optionReturns the (server side) timeout for "volatile data" states.
val get_global_persistent_data_state_timeout :
?secure:bool ->
cookie_scope:[< Eliom_common.cookie_scope ] ->
unit ->
float optionReturns the (server side) timeout for persistent states.
Personalizing timeouts for current state
sets the timeout for service state (server side) for current user, in seconds. None = no timeout
remove the service state timeout for current user (and turn back to the default).
returns the timeout for current service state. None = no timeout
sets the (server side) timeout for volatile data state for current user, in seconds. None = no timeout
remove the "volatile data" state timeout for current user (and turn back to the default).
returns the timeout for current volatile data state. None = no timeout
val set_persistent_data_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
float option ->
unit Lwt.tsets the (server side) timeout for persistent state for current user, in seconds. None = no timeout
remove the persistent state timeout for current user (and turn back to the default).
val get_persistent_data_state_timeout :
cookie_scope:[< Eliom_common.cookie_scope ] ->
?secure:bool ->
unit ->
float option Lwt.treturns the persistent state timeout for current user. None = no timeout
Administrating server side state
Warning: Most these functions must be called when the site information is available, that is, either during a request or during the initialisation phase of the site. Otherwise, it will raise the exception Eliom_common.Eliom_site_information_not_available. If you are using static linking, you must delay the call to this function until the configuration file is read, using Eliom_service.register_eliom_module. Otherwise you will also get this exception.
The type of (volatile) state data tables.
The type of persistent state data tables.
val discard_everything : unit -> unit Lwt.tDiscard all services and persistent and volatile data for every scopes.
Discard all services and persistent and volatile data for one scope.
Discard server side data for all clients, for the given scope.
If the optional parameter ?persistent is not present, both the persistent and volatile data will be removed.
Remove all services registered for clients for the given scope.