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erl_epmd(3erl) Erlang Module Definition erl_epmd(3erl)

NAME

erl_epmd -
Erlang interface towards epmd

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()}

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


register_node(Name, Port) -> Result





register_node(Name, Port, Driver) -> Result

Types:

Name = string()
Port = integer() >= 0
Driver = inet_tcp | inet6_tcp | inet | inet6
Creation = integer() >= 0 | -1
Result = {ok, Creation} | {error, already_registered} | term()

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()}





port_please(Name, Host, Timeout) ->



               {port, Port, Version} |



               noport | closed |



               {error, term()}

Types:

Name = atom() | string()
Host = atom() | string() | inet:ip_address()
Timeout = integer() >= 0 | infinity
Port = Version = integer() >= 0

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}

Types:

Name = atom()
Host = string() | inet:ip_address()
Port = integer() >= 0

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()}

Types:

Name = string()
Host = string() | inet:ip_address()
AddressFamily = inet | inet6
Port = Version = integer() >= 0
Success =
{ok, inet:ip_address()} |
{ok, inet:ip_address(), Port, Version}

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}

Types:

Host = atom() | string() | inet:ip_address()
Name = string()
Port = integer() >= 0
Reason = address | file:posix()

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}]}
kernel 7.2 Ericsson AB