Erlang Programming Examples

Erlang spawn on Node

erlang

-module(helloworld). 
-export([start/0]). 

start() ->
   spawn(node(),fun() -> server("Hello") end). 

server(Message) -> 
   io:fwrite("~p",[Message]).

Erlang Node Distributed Programming

erlang

-module(helloworld). 
-export([start/0]). 

start() ->
   io:fwrite("~p",[node()]).

Erlang spawn Distributed Programming

erlang

-module(helloworld). 
-export([start/0]). 

start() ->
   spawn(fun() -> server("Hello") end). 

server(Message) ->
   io:fwrite("~p",[Message]).

Erlang Receiving a Message on the Port

erlang

-module(helloworld). 
-export([start/0,client/1]). 

start() -> 
   spawn(fun() -> server(4000) end).

server(Port) ->
   {ok, Socket} = gen_udp:open(Port, [binary, {active, false}]), 
   io:format("server opened socket:~p~n",[Socket]), 
   loop(Socket). 

loop(Socket) ->
   inet:setopts(Socket, [{active, once}]), 
   receive 
      {udp, Socket, Host, Port, Bin} -> 
      io:format("server received:~p~n",[Bin]), 
      gen_udp:send(Socket, Host, Port, Bin), 
      loop(Socket) 
   end. 

client(N) -> 
   {ok, Socket} = gen_udp:open(0, [binary]), 
   io:format("client opened socket=~p~n",[Socket]), 
   ok = gen_udp:send(Socket, "localhost", 4000, N), Value = receive 
      {udp, Socket, _, _, Bin} ->
         io:format("client received:~p~n",[Bin]) after 2000 ->
      0 
   end, 
   
gen_udp:close(Socket), 
Value.

Erlang Sending a Message on the Port

erlang

-module(helloworld). 
-export([start/0]). 

start() ->
   {ok, Socket} = gen_udp:open(8789), 
   io:fwrite("~p",[Socket]), 
   io:fwrite("~p",[gen_udp:send 
   (Socket,"localhost",8789,"Hello")]).

Erlang Ports

erlang

-module(helloworld). 
-export([start/0]). 

start() -> 
   {ok, Socket} = gen_udp:open(8789), 
   io:fwrite("~p",[Socket]).

Erlang Processes unregister

erlang

-module(helloworld). 
-export([start/0, call/2]). 

call(Arg1, Arg2) -> 
   io:fwrite("~p~n",[Arg1]). 

start() -> 
   Pid = spawn(?MODULE, call, ["hello", "process"]), 
   register(myprocess, Pid), 
   io:fwrite("~p~n",[whereis(myprocess)]), 
   unregister(myprocess), 
   io:fwrite("~p~n",[whereis(myprocess)]).

Erlang Processes whereis

erlang

-module(helloworld). 
-export([start/0, call/2]). 

call(Arg1, Arg2) -> 
   io:fwrite("~p~n",[Arg1]). 

start() -> 
   Pid = spawn(?MODULE, call, ["hello", "process"]), 
   register(myprocess, Pid), 
   io:fwrite("~p~n",[whereis(myprocess)]).

Erlang Processes register

erlang

-module(helloworld). 
-export([start/0, call/2]). 

call(Arg1, Arg2) -> 
   io:fwrite("~p~n",[Arg1]). 

start() -> 
   Pid = spawn(?MODULE, call, ["hello", "process"]), 
   register(myprocess, Pid), 
   io:fwrite("~p~n",[registered()]).

Erlang self Processes

erlang

-module(helloworld). 
-export([start/0]). 

start() -> 
   io:fwrite("~p~n",[self()]).

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