Module ebus

Description
Data Types
Function Index
Function Details

Main

ebus` interface. This module also works as a wrapper on top
   of `ebus_ps

module.

Behaviours: application.

See also: ebus_ps.

Description

Main

ebus` interface. This module also works as a wrapper on top
   of `ebus_ps

module.

Data Types

dispatch_fun()

dispatch_fun() = fun(([term()]) -> term())

Receives as argument the subscribers list. Then it should choose one subscriber from the given list and return it.

dispatch_opt()

dispatch_opt() = {scope, local | global} | {dispatch_fun, dispatch_fun()}

Available dispatch options.

dispatch_opts()

dispatch_opts() = [dispatch_opt()]

Dispatch options.

handler()

handler() = pid()

options()

options() = ebus_ps_local:options()

sub/4 options.

topic()

topic() = iodata()

Function Index

default_ps_server/0	Returns default `ebus` server name: `ebus_ps`.
dispatch/2	Equivalent to `dispatch(Topic, Message, [])`.
dispatch/3	Equivalent to `dispatch(server(), Topic, Message, Opts)`.
dispatch/4	Sends a message only to one subscriber handler of the `Topic`.
local_subscribers/1	Equivalent to `local_subscribers(server(), Topic)`.
local_subscribers/2	Same as `subscribers/2` but only local subscribers handlers for the given `Topic` are returned.
local_topics/0	Equivalent to `local_topics(server())`.
local_topics/1	Same as `topics/1` but only local topics are returned.
pub/2	Equivalent to `pub(server(), Topic, Message)`.
pub/3	Sends a message to all subscribers of a topic.
pub_from/3	Equivalent to `pub_from(server(), From, Topic, Message)`.
pub_from/4	Same as `pub/3` but message is not sent to `FromHandler`.
server/0	Returns the registered `ebus` server name.
start/0	Starts `ebus` application.
stop/0	Stops `ebus` application.
sub/2	Equivalent to `sub(server(), Handler, Topic)`.
sub/3	Equivalent to `sub(Server, Handler, Topic, [])`.
sub/4	Subscribes the `Handler` given `Topic`.
subscribers/1	Equivalent to `subscribers(server(), Topic)`.
subscribers/2	Returns a set of all subscribers handlers (local and global) for the given `Topic`.
topics/0	Equivalent to `topics(server())`.
topics/1	Returns the list of all topics (local and global) in use.
unsub/2	Equivalent to `unsub(server(), Handler, Topic)`.
unsub/3	Unsubscribes the given `Handler` from the `Topic`.

Function Details

default_ps_server/0

default_ps_server() -> ebus_ps

Returns default ebus server name: ebus_ps.

dispatch/2

dispatch(Topic, Message) -> any()

Equivalent to dispatch(Topic, Message, []).

dispatch/3

dispatch(Topic, Message, Opts) -> any()

Equivalent to dispatch(server(), Topic, Message, Opts).

dispatch/4

dispatch(Server::atom(), Topic::topic(), Message::term(), Opts::dispatch_opts()) -> ok

Sends a message only to one subscriber handler of the Topic.

Server: The registered server name or pid.
Topic: The string topic, for example <<"users:123">>.
Message: Any erlang term.
Opts: The optional list of options. See below.

Options:

{scope, local | global}: define if the message must be delivered to a local or global (any) process. Default is local.
{dispatch_fun, dispatch_fun()}: allows to pass a function to choose a subscriber from the current subscribers handlers to a topic.

Examples:

  > ebus:dispatch("bar", #{topic => "foo", payload => "hi"}).
  ok
  > ebus:dispatch("bar", #{topic => "foo", payload => "hi"}, []).
  ok
  > ebus:dispatch(ebus_ps, "bar", "my message",
      [{scope, global}, {dispatch_fun, fun([H | _]) -> H end}]).
  ok

local_subscribers/1

local_subscribers(Topic) -> any()

Equivalent to local_subscribers(server(), Topic).

local_subscribers/2

local_subscribers(Server::atom(), Topic::topic()) -> [pid()]

Same as subscribers/2 but only local subscribers handlers for the given Topic are returned.

Example:

  > ebus:local_subscribers(ebus_ps, <<"foo">>).
  [<0.48.0>, <0.49.0>]

local_topics/0

local_topics() -> any()

Equivalent to local_topics(server()).

local_topics/1

local_topics(Server::atom()) -> [binary()]

Same as topics/1 but only local topics are returned.

Example:

  > ebus:local_topics().
  [<<"foo">>, <<"bar">>]
  > ebus:local_topics(ebus_ps).
  [<<"foo">>, <<"bar">>]

pub/2

pub(Topic, Message) -> any()

Equivalent to pub(server(), Topic, Message).

pub/3

pub(Server::atom(), Topic::topic(), Message::term()) -> ok | {error, term()}

Sends a message to all subscribers of a topic.

Server: The registered server name or pid.
Topic: The string topic, for example <<"users:123">>.
Message: Any erlang term.

Examples:

  > ebus:pub("bar", #{topic => "foo", payload => "hi"}).
  ok
  > ebus:pub(ebus_ps, "bar", #{topic => "foo", payload => "hi"}).
  ok

pub_from/3

pub_from(From, Topic, Message) -> any()

Equivalent to pub_from(server(), From, Topic, Message).

pub_from/4

pub_from(Server::atom(), FromHandler::handler(), Topic::topic(), Message::term()) -> ok | {error, term()}

Same as pub/3 but message is not sent to FromHandler.

Examples:

  > ebus:pub_from(self(), "foo", <<"message">>).
  ok
  > ebus:pub_from(ebus_ps, self(), "foo", <<"message">>).
  ok

server/0

server() -> atom()

Returns the registered ebus server name.

start/0

start() -> {ok, term()} | {error, term()}

Starts ebus application.

stop/0

stop() -> ok | {error, term()}

Stops ebus application.

sub/2

sub(Handler, Topic) -> any()

Equivalent to sub(server(), Handler, Topic).

sub/3

sub(Server, Handler, Topic) -> any()

Equivalent to sub(Server, Handler, Topic, []).

sub/4

sub(Server::atom(), Handler::handler(), Topic::topic(), Opts::options()) -> ok | {error, term()}

Subscribes the Handler given Topic.

Server: The Pid registered name of the server.
Handler: The subscriber pid to receive pubsub messages.
Topic: The topic to subscribe to, ie: "users:123".
Opts: The optional list of options. See below.

Options:

{link, _}: links the subscriber to the pubsub adapter.
{fastlane, ebus_ps_local:fastlane()}: Provides a fastlane path for the broadcasts for broadcast() events. The fastlane process is notified of a cached message instead of the normal subscriber. Fastlane handlers must implement fastlane/1 callbacks which accepts a broadcast() struct and returns a fastlaned format for the handler.

Examples:

  > ebus:sub(self(), <<"foo">>).
  ok
  > ebus:sub(ebus_ps, self(), <<"foo">>).
  ok
  > ebus:sub(ebus_ps, self(), <<"foo">>, []).
  ok
  > ebus:sub(ebus_ps, self(), <<"foo">>,
      [{fastlane, {FastPid, my_serializer, [<<"event1">>]}]).
  ok

subscribers/1

subscribers(Topic) -> any()

Equivalent to subscribers(server(), Topic).

subscribers/2

subscribers(Server::atom(), Topic::topic()) -> [pid()]

Returns a set of all subscribers handlers (local and global) for the given Topic.

Server: The registered server name or pid.
Topic: The string topic, for example <<"users:123">>.

Example:

  > ebus:subscribers(ebus_ps, <<"foo">>).
  [<0.48.0>, <0.49.0>]

topics/0

topics() -> any()

Equivalent to topics(server()).

topics/1

topics(Server::atom()) -> [binary()]

Returns the list of all topics (local and global) in use. This is an expensive and private operation.

This is an expensive operation. DO NOT USE IT IN PROD

Example:

  > ebus:topics().
  [<<"foo">>, <<"bar">>]
  > ebus:topics(ebus_ps).
  [<<"foo">>, <<"bar">>]

unsub/2

unsub(Handler, Topic) -> any()

Equivalent to unsub(server(), Handler, Topic).

unsub/3

unsub(Server::atom(), Handler::handler(), Topic::topic()) -> ok | {error, term()}

Unsubscribes the given Handler from the Topic.

Server: The registered server name or pid.
Handler: The subscriber pid.
Topic: The string topic, for example <<"users:123">>.

Example:

  > ebus:unsub(self(), <<"foo">>).
  ok
  > ebus:unsub(ebus_ps, self(), <<"foo">>).
  ok

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