erl_epmd - Erlang 23 Documentation

Module

erl_epmd

Module Summary

Erlang interface towards epmd

Since

Module erl_epmd was introduced in OTP R14B.

Description

This module communicates with the EPMD daemon, see epmd. To implement your own epmd module please see ERTS User's Guide: How to Implement an Alternative Node Discovery for Erlang Distribution

Exports

start_link() -> {ok, pid()} | ignore | {error, term()}

OTP 21.0

This function is invoked as this module is added as a child of the erl_distribution supervisor.

register_node(Name, Port) -> Result

OTP 21.0

register_node(Name, Port, Driver) -> Result

OTP 21.0

Types

Registers the node with epmd and tells epmd what port will be used for the current node. It returns a creation number. This number is incremented on each register to help with identifying if a node is reconnecting to epmd.

port_please(Name, Host) ->
{ok, Port, Version} |
noport | closed |
{error, term()}

OTP 21.0

port_please(Name, Host, Timeout) ->
{port, Port, Version} |
noport | closed |
{error, term()}

OTP 21.0

Types

Requests the distribution port for the given node of an EPMD instance. Together with the port it returns a distribution protocol version which has been 5 since Erlang/OTP R6.

listen_port_please(Name, Host) -> {ok, Port}

OTP 23.0

Types

Called by the distribution module to get which port the local node should listen to when accepting new distribution requests.

address_please(Name, Host, AddressFamily) ->
Success | {error, term()}

OTP 21.0

Types

Called by the distribution module to resolves the Host to an IP address of a remote node.

As an optimization this function may also return the port and version of the remote node. If port and version are returned port_please/3 will not be called.

names(Host) -> {ok, [{Name, Port}]} | {error, Reason}

OTP 21.0

Types

Called by net_adm:names/0. Host defaults to the localhost. Returns the names and associated port numbers of the Erlang nodes that epmd registered at the specified host. Returns {error, address} if epmd is not operational.

Example:

(arne@dunn)1> erl_epmd:names(localhost).
{ok,[{"arne",40262}]}