package obus
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Message buses management

Well-known instances
val session : ?switch:Lwt_switch.t -> unit -> t Lwt.t

session ?switch () returns a connection to the user session message bus. Subsequent calls to session will return the same bus. OBus will automatically exit the program when an error happens on the session bus. You can change this behavior by calling OBus_connection.set_on_disconnect.

val system : ?switch:Lwt_switch.t -> unit -> t Lwt.t

system ?switch () returns a connection to the system message bus. As for session, subsequent calls to system will return the same bus. However, if the connection is closed or crashes, system will try to reopen it.

Creation
val of_addresses : ?switch:Lwt_switch.t -> OBus_address.t list -> t Lwt.t

Establish a connection with a message bus. The bus must be accessible with at least one of the given addresses

val register_connection : OBus_connection.t -> unit Lwt.t

Register the given connection to a message bus. It has the side effect of requesting a name to the message bus if not already done.

If the connection is a connection to a message bus, created with one of the function of OBus_connection then register_connection must be called on it before any other functions.

val exit_on_disconnect : exn -> 'a

Function which exit the program as follow:

  • if exn is a fatal error, it prints a message on stderr and exits the program with an exit code of 1
Peer/proxy helpers
val get_peer : t -> OBus_name.bus -> OBus_peer.t Lwt.t

get_peer bus name returns the peer owning the bus name name. If the service is not activated and is activable, then it is started

val get_proxy : t -> OBus_name.bus -> OBus_path.t -> OBus_proxy.t Lwt.t

get_proxy bus name path resolves name with get_peer and returns a proxy for the object with path path on this service

Bus names
val name : t -> OBus_name.bus

Same as OBus_connection.name.

names bus is the signal holding the set of all names we currently own. It raises Invalid_argument if the connection is not a connection to a message bus.

val hello : t -> OBus_name.bus Lwt.t

hello connection sends an hello message to the message bus, which returns the unique connection name of the connection. Note that if the hello message has already been sent, it will fail.

exception Access_denied of string

Exception raised when a name cannot be owned due to security policies

type request_name_result = [
  1. | `Primary_owner
    (*

    You are now the primary owner of the connection

    *)
  2. | `In_queue
    (*

    You will get the name when it will be available

    *)
  3. | `Exists
    (*

    Somebody else already have the name and nobody specified what to do in this case

    *)
  4. | `Already_owner
    (*

    You already have the name

    *)
]
val request_name : t -> ?allow_replacement:bool -> ?replace_existing:bool -> ?do_not_queue:bool -> OBus_name.bus -> request_name_result Lwt.t

Request a name to the bus. This is the way to acquire a well-know name.

All optional parameters default to false, their meaning are:

  • allow_replacement: allow other application to steal this name from you
  • replace_existing: replace any existing owner of the name
  • do_not_queue: do not queue if not available
type release_name_result = [
  1. | `Released
  2. | `Non_existent
  3. | `Not_owner
]
val release_name : t -> OBus_name.bus -> release_name_result Lwt.t
Service starting/discovering
exception Service_unknown of string

Exception raised when a service is not present on a message bus and can not be started automatically

type start_service_by_name_result = [
  1. | `Success
  2. | `Already_running
]
val start_service_by_name : t -> OBus_name.bus -> start_service_by_name_result Lwt.t

Start a service on the given bus by its name

val name_has_owner : t -> OBus_name.bus -> bool Lwt.t

Returns true if the service is currently running, i.e. some application offers it on the message bus

val list_names : t -> OBus_name.bus list Lwt.t

List names currently running on the message bus

val list_activatable_names : t -> OBus_name.bus list Lwt.t

List services that can be activated. A service is automatically activated when you call one of its method or when you use start_service_by_name

exception Name_has_no_owner of string
val get_name_owner : t -> OBus_name.bus -> OBus_name.bus Lwt.t

Return the connection unique name of the given service. Raise a Name_has_no_owner if the given name does not have an owner.

val list_queued_owners : t -> OBus_name.bus -> OBus_name.bus list Lwt.t

Return the connection unique names of the applications waiting for a name

Messages routing

Note that you should prefer using OBus_match.export and OBus_match.remove since they do not add duplicated rules several times.

exception Match_rule_invalid of string

Exception raised when the program tries to send an invalid match rule. This should never happen since values of type OBus_match.rule are always valid.

val add_match : t -> OBus_match.rule -> unit Lwt.t

Add a matching rule on a message bus. This means that every message routed on the message bus matching this rule will be sent to us.

It can raise OBus_error.No_memory.

exception Match_rule_not_found of string
val remove_match : t -> OBus_match.rule -> unit Lwt.t

Remove a match rule from the message bus. It raises Match_rule_not_found if the rule does not exists

Other

These functions are also offered by the message bus

exception Adt_audit_data_unknown of string
exception Selinux_security_context_unknown of string
val update_activation_environment : t -> (string * string) list -> unit Lwt.t
val get_connection_unix_user : t -> OBus_name.bus -> int Lwt.t
val get_connection_unix_process_id : t -> OBus_name.bus -> int Lwt.t
val get_adt_audit_session_data : t -> OBus_name.bus -> string Lwt.t
val get_connection_selinux_security_context : t -> OBus_name.bus -> string Lwt.t
val reload_config : t -> unit Lwt.t
val get_id : t -> OBus_uuid.t Lwt.t
Signals
val name_owner_changed : t -> (OBus_name.bus * OBus_name.bus * OBus_name.bus) OBus_signal.t

This signal is emitted each time the owner of a name (unique connection name or service name) changes.

val name_lost : t -> OBus_name.bus OBus_signal.t
val name_acquired : t -> OBus_name.bus OBus_signal.t