Erlang中的socket编程简单例子
Erlang中gen_tcp用于编写TCP程序,gen_udp用于编写UDP程序。一个简单的TCP服务器echo示例:
Start_echo_server()-> {ok,Listen}=gen_tcp:listen(1234,[binary,{packet,4},{reuseaddr,true},{active,true}]), {ok,socket}=get_tcp:accept(Listen), gen_tcp:close(Listen), loop(Socket). loop(Socket)-> receive {tcp,Socket,Bin}-> io:format(“serverreceivedbinary=~p~n”,[Bin]) Str=binary_to_term(Bin), io:format(“server (unpacked)~p~n”,[Str]), Reply=lib_misc:string2value(Str), io:format(“serverreplying=~p~n”,[Reply]), gen_tcp:send(Socket,term_to_binary(Reply)), loop(Socket); {tcp_closed,Socket}-> Io:format(“ServerSocketclosed~n”) end.
Tcp的echo客户端示例:
echo_client_eval(Str)-> {Ok,Socket}=gen_tcp:connect(“localhost”,2345,[binary,{packet,4}]), ok=gen_tcp:send(Socket,term_to_binary(Str)), receive {tcp,Socket,Bin}-> Io:format(“Clientreceivedbinary =~p~n”,[Bin]), Val=binary_to_term(Bin), io:format(“Clientresult=~p~n”,[Val]), gen_tcp:close(Socket) end.
UDPserver示例
udp_demo_server(Port)-> {ok,Socket}=gen_udp:open(Open,[Binary]), loop(Socket). Loop(Socket)-> receive {udp,Socket,Host,Port,Bin}-> BinReply=…, gen_udp:send(Socket,Host,Port,BinReply), loop(Socket) End.
UDPclient示例:
udp_demo_client(Request)-> {ok,Socket}=gen_udp:open(0,[Binary]), ok=gen_udp:send(Socket,”localhost”,1234,Request), Value= receive {udp,Socket,_,_,Bin}->{ok,Bin} after2000->error end, gen_udp:close(Socket), Value
注意,因为UDP是不可靠的,一定要设一个超时时间,而且Reqeust最好小于500字节。
WebSocket,JS和Erlang相结合,能够实现Web的绝大多数功能。